mirror of
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f009d0ab7e
(2) remove smallbook/cropmarks comments; switching to smallbook is now
automatic w/house style
(3) use `|' alternative convention for SPARC dependent options.
UnGNUish, but the convention is used for other machines in this book.
(4) cease eliding paragraph about purpose of assembler in Hitachi configuration
(5) use SPECIAL-SYMS switch more consistently
(6) formatting improvements from Q1 release
(7) use explicit @page instead of @group in long examples listing
instruction-set summaries (because some new texinfo bug leads to
double-spacing with @group in this context)
(8) rearrange H8/500 instruction-set summary into two cols
(9) include GPL from texinfo directory rather than duplicating here
7434 lines
254 KiB
Plaintext
7434 lines
254 KiB
Plaintext
\input texinfo @c -*-Texinfo-*-
|
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@c Copyright (c) 1991 1992 1993 Free Software Foundation, Inc.
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|
@c %**start of header
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|
@setfilename as.info
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|
@c ---config---
|
|
@c defaults, config file may override:
|
|
@set have-stabs
|
|
@c ---
|
|
@include asdoc-config.texi
|
|
@c ---
|
|
@c common OR combinations of conditions
|
|
@ifset AOUT
|
|
@set aout-bout
|
|
@end ifset
|
|
@ifset BOUT
|
|
@set aout-bout
|
|
@end ifset
|
|
@ifset H8/300
|
|
@set H8
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|
@end ifset
|
|
@ifset H8/500
|
|
@set H8
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|
@end ifset
|
|
@c start Hitachi-SH
|
|
@ifset SH
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|
@set H8
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|
@end ifset
|
|
@c end Hitachi-SH
|
|
@c ------------
|
|
@ifset GENERIC
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|
@settitle Using @value{AS}
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|
@end ifset
|
|
@ifclear GENERIC
|
|
@settitle Using @value{AS} (@value{TARGET})
|
|
@end ifclear
|
|
@setchapternewpage odd
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|
@c %**end of header
|
|
|
|
@ifinfo
|
|
@format
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|
START-INFO-DIR-ENTRY
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|
* As: (as). The GNU assembler.
|
|
END-INFO-DIR-ENTRY
|
|
@end format
|
|
@end ifinfo
|
|
|
|
@finalout
|
|
@syncodeindex ky cp
|
|
|
|
@ifinfo
|
|
This file documents the GNU Assembler "@value{AS}".
|
|
|
|
Copyright (C) 1991, 1992, 1993 Free Software Foundation, Inc.
|
|
|
|
Permission is granted to make and distribute verbatim copies of
|
|
this manual provided the copyright notice and this permission notice
|
|
are preserved on all copies.
|
|
|
|
@ignore
|
|
Permission is granted to process this file through Tex and print the
|
|
results, provided the printed document carries copying permission
|
|
notice identical to this one except for the removal of this paragraph
|
|
(this paragraph not being relevant to the printed manual).
|
|
|
|
@end ignore
|
|
Permission is granted to copy and distribute modified versions of this
|
|
manual under the conditions for verbatim copying, provided also that the
|
|
section entitled ``GNU General Public License'' is included exactly as
|
|
in the original, and provided that the entire resulting derived work is
|
|
distributed under the terms of a permission notice identical to this
|
|
one.
|
|
|
|
Permission is granted to copy and distribute translations of this manual
|
|
into another language, under the above conditions for modified versions,
|
|
except that the section entitled ``GNU General Public License'' may be
|
|
included in a translation approved by the Free Software Foundation
|
|
instead of in the original English.
|
|
@end ifinfo
|
|
|
|
@titlepage
|
|
@title Using @value{AS}
|
|
@subtitle The GNU Assembler
|
|
@ifclear GENERIC
|
|
@subtitle for the @value{TARGET} family
|
|
@end ifclear
|
|
@sp 1
|
|
@subtitle March 1993
|
|
@sp 1
|
|
@sp 13
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|
The Free Software Foundation Inc. thanks The Nice Computer
|
|
Company of Australia for loaning Dean Elsner to write the
|
|
first (Vax) version of @code{as} for Project GNU.
|
|
The proprietors, management and staff of TNCCA thank FSF for
|
|
distracting the boss while they got some work
|
|
done.
|
|
@sp 3
|
|
@author Dean Elsner, Jay Fenlason & friends
|
|
@page
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|
@tex
|
|
{\parskip=0pt
|
|
\hfill {\it Using {\tt @value{AS}}}\par
|
|
\hfill Edited by Roland Pesch for Cygnus Support\par
|
|
}
|
|
%"boxit" macro for figures:
|
|
%Modified from Knuth's ``boxit'' macro from TeXbook (answer to exercise 21.3)
|
|
\gdef\boxit#1#2{\vbox{\hrule\hbox{\vrule\kern3pt
|
|
\vbox{\parindent=0pt\parskip=0pt\hsize=#1\kern3pt\strut\hfil
|
|
#2\hfil\strut\kern3pt}\kern3pt\vrule}\hrule}}%box with visible outline
|
|
\gdef\ibox#1#2{\hbox to #1{#2\hfil}\kern8pt}% invisible box
|
|
@end tex
|
|
|
|
@vskip 0pt plus 1filll
|
|
Copyright @copyright{} 1991, 1992, 1993 Free Software Foundation, Inc.
|
|
|
|
Permission is granted to make and distribute verbatim copies of
|
|
this manual provided the copyright notice and this permission notice
|
|
are preserved on all copies.
|
|
|
|
Permission is granted to copy and distribute modified versions of this
|
|
manual under the conditions for verbatim copying, provided also that the
|
|
section entitled ``GNU General Public License'' is included exactly as
|
|
in the original, and provided that the entire resulting derived work is
|
|
distributed under the terms of a permission notice identical to this
|
|
one.
|
|
|
|
Permission is granted to copy and distribute translations of this manual
|
|
into another language, under the above conditions for modified versions,
|
|
except that the section entitled ``GNU General Public License'' may be
|
|
included in a translation approved by the Free Software Foundation
|
|
instead of in the original English.
|
|
@end titlepage
|
|
|
|
@ifinfo
|
|
@node Top
|
|
@top Using @value{AS}
|
|
|
|
This file is a user guide to the GNU assembler @code{@value{AS}}.
|
|
@ifclear GENERIC
|
|
This version of the file describes @code{@value{AS}} configured to generate
|
|
code for @value{TARGET} architectures.
|
|
@end ifclear
|
|
@menu
|
|
* Overview:: Overview
|
|
* Invoking:: Command-Line Options
|
|
* Syntax:: Syntax
|
|
* Sections:: Sections and Relocation
|
|
* Symbols:: Symbols
|
|
* Expressions:: Expressions
|
|
* Pseudo Ops:: Assembler Directives
|
|
* Machine Dependencies:: Machine Dependent Features
|
|
@ifset GENERIC
|
|
* Copying:: GNU GENERAL PUBLIC LICENSE
|
|
@end ifset
|
|
|
|
* Index:: Index
|
|
@end menu
|
|
@end ifinfo
|
|
|
|
@node Overview
|
|
@chapter Overview
|
|
@iftex
|
|
This manual is a user guide to the GNU assembler @code{@value{AS}}.
|
|
@ifclear GENERIC
|
|
This version of the manual describes @code{@value{AS}} configured to generate
|
|
code for @value{TARGET} architectures.
|
|
@end ifclear
|
|
@end iftex
|
|
|
|
@cindex invocation summary
|
|
@cindex option summary
|
|
@cindex summary of options
|
|
Here is a brief summary of how to invoke @code{@value{AS}}. For details,
|
|
@pxref{Invoking,,Comand-Line Options}.
|
|
|
|
@c We don't use deffn and friends for the following because they seem
|
|
@c to be limited to one line for the header.
|
|
@smallexample
|
|
@value{AS} [ -a | -al | -as ] [ -D ] [ -f ]
|
|
[ -I @var{path} ] [ -K ] [ -L ]
|
|
[ -o @var{objfile} ] [ -R ] [ -v ] [ -w ]
|
|
@ifset A29K
|
|
@c am29k has no machine-dependent assembler options
|
|
@end ifset
|
|
@ifset H8
|
|
@c Hitachi family chips have no machine-dependent assembler options
|
|
@end ifset
|
|
@ifset SPARC
|
|
[ -Av6 | -Av7 | -Av8 | -Asparclite | -bump ]
|
|
@end ifset
|
|
@ifset Z8000
|
|
@c Z8000 has no machine-dependent assembler options
|
|
@end ifset
|
|
@ifset I960
|
|
@c see md_parse_option in tc-i960.c
|
|
[ -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC ]
|
|
[ -b ] [ -norelax ]
|
|
@end ifset
|
|
@ifset M680X0
|
|
[ -l ] [ -mc68000 | -mc68010 | -mc68020 ]
|
|
@end ifset
|
|
[ -- | @var{files} @dots{} ]
|
|
@end smallexample
|
|
|
|
@table @code
|
|
@item -a[dhlns]
|
|
Turn on listings;
|
|
@samp{-ad}, omit debugging pseudo-ops from listing,
|
|
@samp{-ah}, include high-level source,
|
|
@samp{-al}, assembly listing,
|
|
@samp{-an}, no forms processing,
|
|
@samp{-as}, symbols. These options may be combined; @emph{e.g.},
|
|
@samp{-aln} for assembly listing without forms processing.
|
|
By itself, @samp{-a} defaults to @samp{-ahls} --- that is, all listings
|
|
turned on.
|
|
|
|
@item -D
|
|
This option is accepted only for script compatibility with calls to
|
|
other assemblers; it has no effect on @code{@value{AS}}.
|
|
|
|
@item -f
|
|
``fast''---skip preprocessing (assume source is compiler output)
|
|
|
|
@item -I @var{path}
|
|
Add @var{path} to the search list for @code{.include} directives
|
|
|
|
@item -K
|
|
@ifclear DIFF-TBL-KLUGE
|
|
This option is accepted but has no effect on the @value{TARGET} family.
|
|
@end ifclear
|
|
@ifset DIFF-TBL-KLUGE
|
|
Issue warnings when difference tables altered for long displacements.
|
|
@end ifset
|
|
|
|
@item -L
|
|
Keep (in symbol table) local symbols, starting with @samp{L}
|
|
|
|
@item -o @var{objfile}
|
|
Name the object-file output from @code{@value{AS}}
|
|
|
|
@item -R
|
|
Fold data section into text section
|
|
|
|
@item -v
|
|
Announce @code{as} version
|
|
|
|
@item -W
|
|
Suppress warning messages
|
|
|
|
@item -- | @var{files} @dots{}
|
|
Standard input, or source files to assemble.
|
|
|
|
@end table
|
|
|
|
@ifset I960
|
|
The following options are available when @value{AS} is configured for the
|
|
Intel 80960 processor.
|
|
|
|
@table @code
|
|
@item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
|
|
Specify which variant of the 960 architecture is the target.
|
|
|
|
@item -b
|
|
Add code to collect statistics about branches taken.
|
|
|
|
@item -norelax
|
|
Do not alter compare-and-branch instructions for long displacements;
|
|
error if necessary.
|
|
|
|
@end table
|
|
@end ifset
|
|
|
|
@ifset M680X0
|
|
The following options are available when @value{AS} is configured for the
|
|
Motorola 68000 series.
|
|
|
|
@table @code
|
|
|
|
@item -l
|
|
Shorten references to undefined symbols, to one word instead of two.
|
|
|
|
@item -m68000 | -m68008 | -m68010 | -m68020 | -m68030 | -m68040 | -mcpu32
|
|
Specify what processor in the 68000 family is the target. The default
|
|
is normally the 68020, but this can be changed at configuration time.
|
|
|
|
@item -m68881 | -m68882 | -mno-68881 | -mno-68882
|
|
The target machine does (or does not) have a floating-point coprocessor.
|
|
The default is to assume a coprocessor for 68020, 68030, and cpu32. Although
|
|
the basic 68000 is not compatible with the 68881, a combination of the
|
|
two can be specified, since it's possible to do emulation of the
|
|
coprocessor instructions with the main processor.
|
|
|
|
@item -m68851 | -mno-68851
|
|
The target machine does (or does not) have a memory-management
|
|
unit coprocessor. The default is to assume an MMU for 68020 and up.
|
|
|
|
@end table
|
|
@end ifset
|
|
|
|
@ifset SPARC
|
|
The following options are available when @code{@value{AS}} is configured
|
|
for the SPARC architecture:
|
|
|
|
@table @code
|
|
@item -Av6 | -Av7 | -Av8 | -Asparclite
|
|
Explicitly select a variant of the SPARC architecture.
|
|
|
|
@item -bump
|
|
Warn when the assembler switches to another architecture.
|
|
@end table
|
|
@end ifset
|
|
|
|
@menu
|
|
* Manual:: Structure of this Manual
|
|
* GNU Assembler:: @value{AS}, the GNU Assembler
|
|
* Object Formats:: Object File Formats
|
|
* Command Line:: Command Line
|
|
* Input Files:: Input Files
|
|
* Object:: Output (Object) File
|
|
* Errors:: Error and Warning Messages
|
|
@end menu
|
|
|
|
@node Manual
|
|
@section Structure of this Manual
|
|
|
|
@cindex manual, structure and purpose
|
|
This manual is intended to describe what you need to know to use
|
|
@sc{gnu} @code{@value{AS}}. We cover the syntax expected in source files, including
|
|
notation for symbols, constants, and expressions; the directives that
|
|
@code{@value{AS}} understands; and of course how to invoke @code{@value{AS}}.
|
|
|
|
@ifclear GENERIC
|
|
We also cover special features in the @value{TARGET}
|
|
configuration of @code{@value{AS}}, including assembler directives.
|
|
@end ifclear
|
|
@ifset GENERIC
|
|
This manual also describes some of the machine-dependent features of
|
|
various flavors of the assembler.
|
|
@end ifset
|
|
@ifset INTERNALS
|
|
This manual also describes how the assembler works internally, and
|
|
provides some information that may be useful to people attempting to
|
|
port the assembler to another machine.
|
|
@end ifset
|
|
@refill
|
|
|
|
@cindex machine instructions (not covered)
|
|
On the other hand, this manual is @emph{not} intended as an introduction
|
|
to programming in assembly language---let alone programming in general!
|
|
In a similar vein, we make no attempt to introduce the machine
|
|
architecture; we do @emph{not} describe the instruction set, standard
|
|
mnemonics, registers or addressing modes that are standard to a
|
|
particular architecture.
|
|
@ifset GENERIC
|
|
You may want to consult the manufacturer's
|
|
machine architecture manual for this information.
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset H8/300
|
|
For information on the H8/300 machine instruction set, see @cite{H8/300
|
|
Series Programming Manual} (Hitachi ADE--602--025).
|
|
@end ifset
|
|
@ifset H8/500
|
|
For information on the H8/500 machine instruction set, see @cite{H8/500
|
|
Series Programming Manual} (Hitachi M21T001).
|
|
@end ifset
|
|
@c start Hitachi-SH
|
|
@ifset SH
|
|
For information on the Hitachi SH machine instruction set, see
|
|
@cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
|
|
@end ifset
|
|
@c end Hitachi-SH
|
|
@ifset Z8000
|
|
For information on the Z8000 machine instruction set, see @cite{Z8000 CPU Technical Manual}
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@c I think this is premature---pesch@cygnus.com, 17jan1991
|
|
@ignore
|
|
Throughout this manual, we assume that you are running @dfn{GNU},
|
|
the portable operating system from the @dfn{Free Software
|
|
Foundation, Inc.}. This restricts our attention to certain kinds of
|
|
computer (in particular, the kinds of computers that GNU can run on);
|
|
once this assumption is granted examples and definitions need less
|
|
qualification.
|
|
|
|
@code{@value{AS}} is part of a team of programs that turn a high-level
|
|
human-readable series of instructions into a low-level
|
|
computer-readable series of instructions. Different versions of
|
|
@code{@value{AS}} are used for different kinds of computer.
|
|
@end ignore
|
|
|
|
@c There used to be a section "Terminology" here, which defined
|
|
@c "contents", "byte", "word", and "long". Defining "word" to any
|
|
@c particular size is confusing when the .word directive may generate 16
|
|
@c bits on one machine and 32 bits on another; in general, for the user
|
|
@c version of this manual, none of these terms seem essential to define.
|
|
@c They were used very little even in the former draft of the manual;
|
|
@c this draft makes an effort to avoid them (except in names of
|
|
@c directives).
|
|
|
|
@node GNU Assembler
|
|
@section @value{AS}, the GNU Assembler
|
|
|
|
GNU @code{as} is really a family of assemblers.
|
|
@ifclear GENERIC
|
|
This manual describes @code{@value{AS}}, a member of that family which is
|
|
configured for the @value{TARGET} architectures.
|
|
@end ifclear
|
|
If you use (or have used) the GNU assembler on one architecture, you
|
|
should find a fairly similar environment when you use it on another
|
|
architecture. Each version has much in common with the others,
|
|
including object file formats, most assembler directives (often called
|
|
@dfn{pseudo-ops}) and assembler syntax.@refill
|
|
|
|
@cindex purpose of @sc{gnu} @code{@value{AS}}
|
|
@code{@value{AS}} is primarily intended to assemble the output of the
|
|
GNU C compiler @code{@value{GCC}} for use by the linker
|
|
@code{@value{LD}}. Nevertheless, we've tried to make @code{@value{AS}}
|
|
assemble correctly everything that other assemblers for the same
|
|
machine would assemble.
|
|
@ifset VAX
|
|
Any exceptions are documented explicitly (@pxref{Machine Dependencies}).
|
|
@end ifset
|
|
@ifset M680X0
|
|
@c This remark should appear in generic version of manual; assumption
|
|
@c here is that generic version sets M680x0.
|
|
This doesn't mean @code{@value{AS}} always uses the same syntax as another
|
|
assembler for the same architecture; for example, we know of several
|
|
incompatible versions of 680x0 assembly language syntax.
|
|
@end ifset
|
|
|
|
Unlike older assemblers, @code{@value{AS}} is designed to assemble a source
|
|
program in one pass of the source file. This has a subtle impact on the
|
|
@kbd{.org} directive (@pxref{Org,,@code{.org}}).
|
|
|
|
@node Object Formats
|
|
@section Object File Formats
|
|
|
|
@cindex object file format
|
|
The GNU assembler can be configured to produce several alternative
|
|
object file formats. For the most part, this does not affect how you
|
|
write assembly language programs; but directives for debugging symbols
|
|
are typically different in different file formats. @xref{Symbol
|
|
Attributes,,Symbol Attributes}.
|
|
@ifclear GENERIC
|
|
@ifclear MULTI-OBJ
|
|
On the @value{TARGET}, @code{@value{AS}} is configured to produce
|
|
@value{OBJ-NAME} format object files.
|
|
@end ifclear
|
|
@c The following should exhaust all configs that set MULTI-OBJ, ideally
|
|
@ifset A29K
|
|
On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
|
|
@code{a.out} or COFF format object files.
|
|
@end ifset
|
|
@ifset I960
|
|
On the @value{TARGET}, @code{@value{AS}} can be configured to produce either
|
|
@code{b.out} or COFF format object files.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@node Command Line
|
|
@section Command Line
|
|
|
|
@cindex command line conventions
|
|
After the program name @code{@value{AS}}, the command line may contain
|
|
options and file names. Options may appear in any order, and may be
|
|
before, after, or between file names. The order of file names is
|
|
significant.
|
|
|
|
@cindex standard input, as input file
|
|
@kindex --
|
|
@file{--} (two hyphens) by itself names the standard input file
|
|
explicitly, as one of the files for @code{@value{AS}} to assemble.
|
|
|
|
@cindex options, command line
|
|
Except for @samp{--} any command line argument that begins with a
|
|
hyphen (@samp{-}) is an option. Each option changes the behavior of
|
|
@code{@value{AS}}. No option changes the way another option works. An
|
|
option is a @samp{-} followed by one or more letters; the case of
|
|
the letter is important. All options are optional.
|
|
|
|
Some options expect exactly one file name to follow them. The file
|
|
name may either immediately follow the option's letter (compatible
|
|
with older assemblers) or it may be the next command argument (GNU
|
|
standard). These two command lines are equivalent:
|
|
|
|
@smallexample
|
|
@value{AS} -o my-object-file.o mumble.s
|
|
@value{AS} -omy-object-file.o mumble.s
|
|
@end smallexample
|
|
|
|
@node Input Files
|
|
@section Input Files
|
|
|
|
@cindex input
|
|
@cindex source program
|
|
@cindex files, input
|
|
We use the phrase @dfn{source program}, abbreviated @dfn{source}, to
|
|
describe the program input to one run of @code{@value{AS}}. The program may
|
|
be in one or more files; how the source is partitioned into files
|
|
doesn't change the meaning of the source.
|
|
|
|
@c I added "con" prefix to "catenation" just to prove I can overcome my
|
|
@c APL training... pesch@cygnus.com
|
|
The source program is a concatenation of the text in all the files, in the
|
|
order specified.
|
|
|
|
Each time you run @code{@value{AS}} it assembles exactly one source
|
|
program. The source program is made up of one or more files.
|
|
(The standard input is also a file.)
|
|
|
|
You give @code{@value{AS}} a command line that has zero or more input file
|
|
names. The input files are read (from left file name to right). A
|
|
command line argument (in any position) that has no special meaning
|
|
is taken to be an input file name.
|
|
|
|
If you give @code{@value{AS}} no file names it attempts to read one input file
|
|
from the @code{@value{AS}} standard input, which is normally your terminal. You
|
|
may have to type @key{ctl-D} to tell @code{@value{AS}} there is no more program
|
|
to assemble.
|
|
|
|
Use @samp{--} if you need to explicitly name the standard input file
|
|
in your command line.
|
|
|
|
If the source is empty, @code{@value{AS}} will produce a small, empty object
|
|
file.
|
|
|
|
@subheading Filenames and Line-numbers
|
|
|
|
@cindex input file linenumbers
|
|
@cindex line numbers, in input files
|
|
There are two ways of locating a line in the input file (or files) and
|
|
either may be used in reporting error messages. One way refers to a line
|
|
number in a physical file; the other refers to a line number in a
|
|
``logical'' file. @xref{Errors, ,Error and Warning Messages}.
|
|
|
|
@dfn{Physical files} are those files named in the command line given
|
|
to @code{@value{AS}}.
|
|
|
|
@dfn{Logical files} are simply names declared explicitly by assembler
|
|
directives; they bear no relation to physical files. Logical file names
|
|
help error messages reflect the original source file, when @code{@value{AS}}
|
|
source is itself synthesized from other files.
|
|
@xref{App-File,,@code{.app-file}}.
|
|
|
|
@node Object
|
|
@section Output (Object) File
|
|
|
|
@cindex object file
|
|
@cindex output file
|
|
@kindex a.out
|
|
@kindex .o
|
|
Every time you run @code{@value{AS}} it produces an output file, which is
|
|
your assembly language program translated into numbers. This file
|
|
is the object file, named
|
|
@ifset BOUT
|
|
@code{b.out},
|
|
@ifset GENERIC
|
|
if @code{@value{AS}} is configured for the Intel 80960, or
|
|
@end ifset
|
|
@end ifset
|
|
@ifclear BOUT
|
|
@code{a.out},
|
|
@end ifclear
|
|
unless you tell @code{@value{AS}} to
|
|
give it another name by using the @code{-o} option. Conventionally,
|
|
object file names end with @file{.o}. The default name of
|
|
@file{a.out} is used for historical reasons: older assemblers were
|
|
capable of assembling self-contained programs directly into a
|
|
runnable program.
|
|
(For some formats, this isn't currently possible, but it can be done for
|
|
@code{a.out} format.)
|
|
|
|
@cindex linker
|
|
@kindex ld
|
|
The object file is meant for input to the linker @code{@value{LD}}. It contains
|
|
assembled program code, information to help @code{@value{LD}} integrate
|
|
the assembled program into a runnable file, and (optionally) symbolic
|
|
information for the debugger.
|
|
|
|
@c link above to some info file(s) like the description of a.out.
|
|
@c don't forget to describe GNU info as well as Unix lossage.
|
|
|
|
@node Errors
|
|
@section Error and Warning Messages
|
|
|
|
@cindex error messsages
|
|
@cindex warning messages
|
|
@cindex messages from @code{@value{AS}}
|
|
@code{@value{AS}} may write warnings and error messages to the standard error
|
|
file (usually your terminal). This should not happen when a compiler
|
|
runs @code{@value{AS}} automatically. Warnings report an assumption made so
|
|
that @code{@value{AS}} could keep assembling a flawed program; errors report a
|
|
grave problem that stops the assembly.
|
|
|
|
@cindex format of warning messages
|
|
Warning messages have the format
|
|
|
|
@smallexample
|
|
file_name:@b{NNN}:Warning Message Text
|
|
@end smallexample
|
|
|
|
@noindent
|
|
@cindex line numbers, in warnings/errors
|
|
(where @b{NNN} is a line number). If a logical file name has been given
|
|
(@pxref{App-File,,@code{.app-file}}) it is used for the filename,
|
|
otherwise the name of the current input file is used. If a logical line
|
|
number was given
|
|
@ifset GENERIC
|
|
(@pxref{Line,,@code{.line}})
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifclear A29K
|
|
(@pxref{Line,,@code{.line}})
|
|
@end ifclear
|
|
@ifset A29K
|
|
(@pxref{Ln,,@code{.ln}})
|
|
@end ifset
|
|
@end ifclear
|
|
then it is used to calculate the number printed,
|
|
otherwise the actual line in the current source file is printed. The
|
|
message text is intended to be self explanatory (in the grand Unix
|
|
tradition).
|
|
|
|
@cindex format of error messages
|
|
Error messages have the format
|
|
@smallexample
|
|
file_name:@b{NNN}:FATAL:Error Message Text
|
|
@end smallexample
|
|
The file name and line number are derived as for warning
|
|
messages. The actual message text may be rather less explanatory
|
|
because many of them aren't supposed to happen.
|
|
|
|
@node Invoking
|
|
@chapter Command-Line Options
|
|
|
|
@cindex options, all versions of @code{@value{AS}}
|
|
This chapter describes command-line options available in @emph{all}
|
|
versions of the GNU assembler; @pxref{Machine Dependencies}, for options specific
|
|
@ifclear GENERIC
|
|
to the @value{TARGET}.
|
|
@end ifclear
|
|
@ifset GENERIC
|
|
to particular machine architectures.
|
|
@end ifset
|
|
|
|
If you are invoking @code{@value{AS}} via the GNU C compiler (version 2), you
|
|
can use the @samp{-Wa} option to pass arguments through to the
|
|
assembler. The assembler arguments must be separated from each other
|
|
(and the @samp{-Wa}) by commas. For example:
|
|
|
|
@smallexample
|
|
gcc -c -g -O -Wa,-alh,-L file.c
|
|
@end smallexample
|
|
|
|
will cause a listing to be emitted to standard output with high-level
|
|
and assembly source.
|
|
|
|
Many compiler command-line options, such as @samp{-R} and many
|
|
machine-specific options, will be automatically be passed to the
|
|
assembler by the compiler, so usually you do not need to use this
|
|
@samp{-Wa} mechanism.
|
|
|
|
@menu
|
|
* a:: -a[dhlns] enable listings
|
|
* D:: -D for compatibility
|
|
* f:: -f to work faster
|
|
* I:: -I for .include search path
|
|
@ifclear DIFF-TBL-KLUGE
|
|
* K:: -K for compatibility
|
|
@end ifclear
|
|
@ifset DIFF-TBL-KLUGE
|
|
* K:: -K for difference tables
|
|
@end ifset
|
|
|
|
* L:: -L to retain local labels
|
|
* o:: -o to name the object file
|
|
* R:: -R to join data and text sections
|
|
* v:: -v to announce version
|
|
* W:: -W to suppress warnings
|
|
@end menu
|
|
|
|
@node a
|
|
@section Enable Listings: @code{-a[dhlns]}
|
|
|
|
@kindex -a
|
|
@kindex -ad
|
|
@kindex -ah
|
|
@kindex -al
|
|
@kindex -an
|
|
@kindex -as
|
|
@cindex listings, enabling
|
|
@cindex assembly listings, enabling
|
|
|
|
These options enable listing output from the assembler. By itself,
|
|
@samp{-a} requests high-level, assembly, and symbols listing.
|
|
Other letters may be used to select specific options for the list:
|
|
@samp{-ah} requests a high-level language listing,
|
|
@samp{-al} requests an output-program assembly listing, and
|
|
@samp{-as} requests a symbol table listing.
|
|
High-level listings require that a compiler debugging option like
|
|
@samp{-g} be used, and that assembly listings (@samp{-al}) be requested
|
|
also.
|
|
|
|
The @samp{-ad} option may be used to omit debugging pseudo-ops from the
|
|
listing.
|
|
|
|
Once you have specified one of these options, you can further control
|
|
listing output and its appearance using the directives @code{.list},
|
|
@code{.nolist}, @code{.psize}, @code{.eject}, @code{.title}, and
|
|
@code{.sbttl}.
|
|
The @samp{-an} option turns off all forms processing.
|
|
If you do not request listing output with one of the @samp{-a} options, the
|
|
listing-control directives have no effect.
|
|
|
|
The letters after @samp{-a} may be combined into one option,
|
|
@emph{e.g.}, @samp{-aln}.
|
|
|
|
@node D
|
|
@section @code{-D}
|
|
|
|
@kindex -D
|
|
This option has no effect whatsoever, but it is accepted to make it more
|
|
likely that scripts written for other assemblers will also work with
|
|
@code{@value{AS}}.
|
|
|
|
@node f
|
|
@section Work Faster: @code{-f}
|
|
|
|
@kindex -f
|
|
@cindex trusted compiler
|
|
@cindex faster processing (@code{-f})
|
|
@samp{-f} should only be used when assembling programs written by a
|
|
(trusted) compiler. @samp{-f} stops the assembler from pre-processing
|
|
the input file(s) before assembling them. @xref{Pre-processing,
|
|
,Pre-processing}.
|
|
|
|
@quotation
|
|
@emph{Warning:} if the files actually need to be pre-processed (if they
|
|
contain comments, for example), @code{@value{AS}} will not work correctly if
|
|
@samp{-f} is used.
|
|
@end quotation
|
|
|
|
@node I
|
|
@section @code{.include} search path: @code{-I} @var{path}
|
|
|
|
@kindex -I @var{path}
|
|
@cindex paths for @code{.include}
|
|
@cindex search path for @code{.include}
|
|
@cindex @code{include} directive search path
|
|
Use this option to add a @var{path} to the list of directories
|
|
@code{@value{AS}} will search for files specified in @code{.include}
|
|
directives (@pxref{Include,,@code{.include}}). You may use @code{-I} as
|
|
many times as necessary to include a variety of paths. The current
|
|
working directory is always searched first; after that, @code{@value{AS}}
|
|
searches any @samp{-I} directories in the same order as they were
|
|
specified (left to right) on the command line.
|
|
|
|
@node K
|
|
@section Difference Tables: @code{-K}
|
|
|
|
@kindex -K
|
|
@ifclear DIFF-TBL-KLUGE
|
|
On the @value{TARGET} family, this option is allowed, but has no effect. It is
|
|
permitted for compatibility with the GNU assembler on other platforms,
|
|
where it can be used to warn when the assembler alters the machine code
|
|
generated for @samp{.word} directives in difference tables. The @value{TARGET}
|
|
family does not have the addressing limitations that sometimes lead to this
|
|
alteration on other platforms.
|
|
@end ifclear
|
|
|
|
@ifset DIFF-TBL-KLUGE
|
|
@cindex difference tables, warning
|
|
@cindex warning for altered difference tables
|
|
@code{@value{AS}} sometimes alters the code emitted for directives of the form
|
|
@samp{.word @var{sym1}-@var{sym2}}; @pxref{Word,,@code{.word}}.
|
|
You can use the @samp{-K} option if you want a warning issued when this
|
|
is done.
|
|
@end ifset
|
|
|
|
@node L
|
|
@section Include Local Labels: @code{-L}
|
|
|
|
@kindex -L
|
|
@cindex local labels, retaining in output
|
|
Labels beginning with @samp{L} (upper case only) are called @dfn{local
|
|
labels}. @xref{Symbol Names}. Normally you don't see such labels when
|
|
debugging, because they are intended for the use of programs (like
|
|
compilers) that compose assembler programs, not for your notice.
|
|
Normally both @code{@value{AS}} and @code{@value{LD}} discard such labels, so you don't
|
|
normally debug with them.
|
|
|
|
This option tells @code{@value{AS}} to retain those @samp{L@dots{}} symbols
|
|
in the object file. Usually if you do this you also tell the linker
|
|
@code{@value{LD}} to preserve symbols whose names begin with @samp{L}.
|
|
|
|
@node o
|
|
@section Name the Object File: @code{-o}
|
|
|
|
@kindex -o
|
|
@cindex naming object file
|
|
@cindex object file name
|
|
There is always one object file output when you run @code{@value{AS}}. By
|
|
default it has the name
|
|
@ifset GENERIC
|
|
@ifset I960
|
|
@file{a.out} (or @file{b.out}, for Intel 960 targets only).
|
|
@end ifset
|
|
@ifclear I960
|
|
@file{a.out}.
|
|
@end ifclear
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset I960
|
|
@file{b.out}.
|
|
@end ifset
|
|
@ifclear I960
|
|
@file{a.out}.
|
|
@end ifclear
|
|
@end ifclear
|
|
You use this option (which takes exactly one filename) to give the
|
|
object file a different name.
|
|
|
|
Whatever the object file is called, @code{@value{AS}} will overwrite any
|
|
existing file of the same name.
|
|
|
|
@node R
|
|
@section Join Data and Text Sections: @code{-R}
|
|
|
|
@kindex -R
|
|
@cindex data and text sections, joining
|
|
@cindex text and data sections, joining
|
|
@cindex joining text and data sections
|
|
@cindex merging text and data sections
|
|
@code{-R} tells @code{@value{AS}} to write the object file as if all
|
|
data-section data lives in the text section. This is only done at
|
|
the very last moment: your binary data are the same, but data
|
|
section parts are relocated differently. The data section part of
|
|
your object file is zero bytes long because all its bytes are
|
|
appended to the text section. (@xref{Sections,,Sections and Relocation}.)
|
|
|
|
When you specify @code{-R} it would be possible to generate shorter
|
|
address displacements (because we don't have to cross between text and
|
|
data section). We refrain from doing this simply for compatibility with
|
|
older versions of @code{@value{AS}}. In future, @code{-R} may work this way.
|
|
|
|
@ifset COFF
|
|
When @code{@value{AS}} is configured for COFF output,
|
|
this option is only useful if you use sections named @samp{.text} and
|
|
@samp{.data}.
|
|
@end ifset
|
|
|
|
@node v
|
|
@section Announce Version: @code{-v}
|
|
|
|
@kindex -v
|
|
@kindex -version
|
|
@cindex @code{@value{AS}} version
|
|
@cindex version of @code{@value{AS}}
|
|
You can find out what version of as is running by including the
|
|
option @samp{-v} (which you can also spell as @samp{-version}) on the
|
|
command line.
|
|
|
|
@node W
|
|
@section Suppress Warnings: @code{-W}
|
|
|
|
@kindex -W
|
|
@cindex suppressing warnings
|
|
@cindex warnings, suppressing
|
|
@code{@value{AS}} should never give a warning or error message when
|
|
assembling compiler output. But programs written by people often
|
|
cause @code{@value{AS}} to give a warning that a particular assumption was
|
|
made. All such warnings are directed to the standard error file.
|
|
If you use this option, no warnings are issued. This option only
|
|
affects the warning messages: it does not change any particular of how
|
|
@code{@value{AS}} assembles your file. Errors, which stop the assembly, are
|
|
still reported.
|
|
|
|
@node Syntax
|
|
@chapter Syntax
|
|
|
|
@cindex machine-independent syntax
|
|
@cindex syntax, machine-independent
|
|
This chapter describes the machine-independent syntax allowed in a
|
|
source file. @code{@value{AS}} syntax is similar to what many other
|
|
assemblers use; it is inspired by the BSD 4.2
|
|
@ifclear VAX
|
|
assembler.
|
|
@end ifclear
|
|
@ifset VAX
|
|
assembler, except that @code{@value{AS}} does not assemble Vax bit-fields.
|
|
@end ifset
|
|
|
|
@menu
|
|
* Pre-processing:: Pre-processing
|
|
* Whitespace:: Whitespace
|
|
* Comments:: Comments
|
|
* Symbol Intro:: Symbols
|
|
* Statements:: Statements
|
|
* Constants:: Constants
|
|
@end menu
|
|
|
|
@node Pre-processing
|
|
@section Pre-Processing
|
|
|
|
@cindex preprocessing
|
|
The pre-processor:
|
|
@itemize @bullet
|
|
@cindex whitespace, removed by preprocessor
|
|
@item
|
|
adjusts and removes extra whitespace. It leaves one space or tab before
|
|
the keywords on a line, and turns any other whitespace on the line into
|
|
a single space.
|
|
|
|
@cindex comments, removed by preprocessor
|
|
@item
|
|
removes all comments, replacing them with a single space, or an
|
|
appropriate number of newlines.
|
|
|
|
@cindex constants, converted by preprocessor
|
|
@item
|
|
converts character constants into the appropriate numeric values.
|
|
@end itemize
|
|
|
|
Excess whitespace, comments, and character constants
|
|
cannot be used in the portions of the input text that are not
|
|
pre-processed.
|
|
|
|
@cindex turning preprocessing on and off
|
|
@cindex preprocessing, turning on and off
|
|
@kindex #NO_APP
|
|
@kindex #APP
|
|
If the first line of an input file is @code{#NO_APP} or the @samp{-f}
|
|
option is given, the input file will not be pre-processed. Within such
|
|
an input file, parts of the file can be pre-processed by putting a line
|
|
that says @code{#APP} before the text that should be pre-processed, and
|
|
putting a line that says @code{#NO_APP} after them. This feature is
|
|
mainly intend to support @code{asm} statements in compilers whose output
|
|
normally does not need to be pre-processed.
|
|
|
|
@node Whitespace
|
|
@section Whitespace
|
|
|
|
@cindex whitespace
|
|
@dfn{Whitespace} is one or more blanks or tabs, in any order.
|
|
Whitespace is used to separate symbols, and to make programs neater for
|
|
people to read. Unless within character constants
|
|
(@pxref{Characters,,Character Constants}), any whitespace means the same
|
|
as exactly one space.
|
|
|
|
@node Comments
|
|
@section Comments
|
|
|
|
@cindex comments
|
|
There are two ways of rendering comments to @code{@value{AS}}. In both
|
|
cases the comment is equivalent to one space.
|
|
|
|
Anything from @samp{/*} through the next @samp{*/} is a comment.
|
|
This means you may not nest these comments.
|
|
|
|
@smallexample
|
|
/*
|
|
The only way to include a newline ('\n') in a comment
|
|
is to use this sort of comment.
|
|
*/
|
|
|
|
/* This sort of comment does not nest. */
|
|
@end smallexample
|
|
|
|
@cindex line comment character
|
|
Anything from the @dfn{line comment} character to the next newline
|
|
is considered a comment and is ignored. The line comment character is
|
|
@ifset VAX
|
|
@samp{#} on the Vax;
|
|
@end ifset
|
|
@ifset I960
|
|
@samp{#} on the i960;
|
|
@end ifset
|
|
@ifset SPARC
|
|
@samp{!} on the SPARC;
|
|
@end ifset
|
|
@ifset M680X0
|
|
@samp{|} on the 680x0;
|
|
@end ifset
|
|
@ifset A29K
|
|
@samp{;} for the AMD 29K family;
|
|
@end ifset
|
|
@ifset H8/300
|
|
@samp{;} for the H8/300 family;
|
|
@end ifset
|
|
@ifset H8/500
|
|
@samp{!} for the H8/500 family;
|
|
@end ifset
|
|
@c start Hitachi-SH
|
|
@ifset SH
|
|
@samp{!} for the Hitachi SH;
|
|
@end ifset
|
|
@c end Hitachi-SH
|
|
@ifset Z8000
|
|
@samp{!} for the Z8000;
|
|
@end ifset
|
|
see @ref{Machine Dependencies}. @refill
|
|
@c FIXME What about i386, m88k, i860?
|
|
|
|
@ifset GENERIC
|
|
On some machines there are two different line comment characters. One
|
|
will only begin a comment if it is the first non-whitespace character on
|
|
a line, while the other will always begin a comment.
|
|
@end ifset
|
|
|
|
@kindex #
|
|
@cindex lines starting with @code{#}
|
|
@cindex logical line numbers
|
|
To be compatible with past assemblers, a special interpretation is
|
|
given to lines that begin with @samp{#}. Following the @samp{#} an
|
|
absolute expression (@pxref{Expressions}) is expected: this will be
|
|
the logical line number of the @b{next} line. Then a string
|
|
(@xref{Strings}.) is allowed: if present it is a new logical file
|
|
name. The rest of the line, if any, should be whitespace.
|
|
|
|
If the first non-whitespace characters on the line are not numeric,
|
|
the line is ignored. (Just like a comment.)
|
|
@smallexample
|
|
# This is an ordinary comment.
|
|
# 42-6 "new_file_name" # New logical file name
|
|
# This is logical line # 36.
|
|
@end smallexample
|
|
This feature is deprecated, and may disappear from future versions
|
|
of @code{@value{AS}}.
|
|
|
|
@node Symbol Intro
|
|
@section Symbols
|
|
|
|
@cindex characters used in symbols
|
|
@ifclear SPECIAL-SYMS
|
|
A @dfn{symbol} is one or more characters chosen from the set of all
|
|
letters (both upper and lower case), digits and the three characters
|
|
@samp{_.$}.
|
|
@end ifclear
|
|
@ifset SPECIAL-SYMS
|
|
@ifclear GENERIC
|
|
@ifset H8
|
|
A @dfn{symbol} is one or more characters chosen from the set of all
|
|
letters (both upper and lower case), digits and the three characters
|
|
@samp{._$}. (Save that, on the H8/300 only, you may not use @samp{$} in
|
|
symbol names.)
|
|
@end ifset
|
|
@end ifclear
|
|
@end ifset
|
|
@ifset GENERIC
|
|
On most machines, you can also use @code{$} in symbol names; exceptions
|
|
are noted in @ref{Machine Dependencies}.
|
|
@end ifset
|
|
No symbol may begin with a digit. Case is significant.
|
|
There is no length limit: all characters are significant. Symbols are
|
|
delimited by characters not in that set, or by the beginning of a file
|
|
(since the source program must end with a newline, the end of a file is
|
|
not a possible symbol delimiter). @xref{Symbols}.
|
|
@cindex length of symbols
|
|
|
|
@node Statements
|
|
@section Statements
|
|
|
|
@cindex statements, structure of
|
|
@cindex line separator character
|
|
@cindex statement separator character
|
|
@ifclear GENERIC
|
|
@ifclear abnormal-separator
|
|
A @dfn{statement} ends at a newline character (@samp{\n}) or at a
|
|
semicolon (@samp{;}). The newline or semicolon is considered part of
|
|
the preceding statement. Newlines and semicolons within character
|
|
constants are an exception: they don't end statements.
|
|
@end ifclear
|
|
@ifset abnormal-separator
|
|
@ifset A29K
|
|
A @dfn{statement} ends at a newline character (@samp{\n}) or an ``at''
|
|
sign (@samp{@@}). The newline or at sign is considered part of the
|
|
preceding statement. Newlines and at signs within character constants
|
|
are an exception: they don't end statements.
|
|
@end ifset
|
|
@ifset H8
|
|
A @dfn{statement} ends at a newline character (@samp{\n}); or (for the
|
|
H8/300) a dollar sign (@samp{$}); or (for the
|
|
@c start Hitachi-SH
|
|
Hitachi-SH or the
|
|
@c end Hitachi-SH
|
|
H8/500) a semicolon
|
|
(@samp{;}). The newline or separator character is considered part of
|
|
the preceding statement. Newlines and separators within character
|
|
constants are an exception: they don't end statements.
|
|
@end ifset
|
|
@end ifset
|
|
@end ifclear
|
|
@ifset GENERIC
|
|
A @dfn{statement} ends at a newline character (@samp{\n}) or line
|
|
separator character. (The line separator is usually @samp{;}, unless
|
|
this conflicts with the comment character; @pxref{Machine Dependencies}.) The
|
|
newline or separator character is considered part of the preceding
|
|
statement. Newlines and separators within character constants are an
|
|
exception: they don't end statements.
|
|
@end ifset
|
|
|
|
@cindex newline, required at file end
|
|
@cindex EOF, newline must precede
|
|
It is an error to end any statement with end-of-file: the last
|
|
character of any input file should be a newline.@refill
|
|
|
|
@cindex continuing statements
|
|
@cindex multi-line statements
|
|
@cindex statement on multiple lines
|
|
You may write a statement on more than one line if you put a
|
|
backslash (@kbd{\}) immediately in front of any newlines within the
|
|
statement. When @code{@value{AS}} reads a backslashed newline both
|
|
characters are ignored. You can even put backslashed newlines in
|
|
the middle of symbol names without changing the meaning of your
|
|
source program.
|
|
|
|
An empty statement is allowed, and may include whitespace. It is ignored.
|
|
|
|
@cindex instructions and directives
|
|
@cindex directives and instructions
|
|
@c "key symbol" is not used elsewhere in the document; seems pedantic to
|
|
@c @defn{} it in that case, as was done previously... pesch@cygnus.com,
|
|
@c 13feb91.
|
|
A statement begins with zero or more labels, optionally followed by a
|
|
key symbol which determines what kind of statement it is. The key
|
|
symbol determines the syntax of the rest of the statement. If the
|
|
symbol begins with a dot @samp{.} then the statement is an assembler
|
|
directive: typically valid for any computer. If the symbol begins with
|
|
a letter the statement is an assembly language @dfn{instruction}: it
|
|
will assemble into a machine language instruction.
|
|
@ifset GENERIC
|
|
Different versions of @code{@value{AS}} for different computers will
|
|
recognize different instructions. In fact, the same symbol may
|
|
represent a different instruction in a different computer's assembly
|
|
language.@refill
|
|
@end ifset
|
|
|
|
@cindex @code{:} (label)
|
|
@cindex label (@code{:})
|
|
A label is a symbol immediately followed by a colon (@code{:}).
|
|
Whitespace before a label or after a colon is permitted, but you may not
|
|
have whitespace between a label's symbol and its colon. @xref{Labels}.
|
|
|
|
@smallexample
|
|
label: .directive followed by something
|
|
another_label: # This is an empty statement.
|
|
instruction operand_1, operand_2, @dots{}
|
|
@end smallexample
|
|
|
|
@node Constants
|
|
@section Constants
|
|
|
|
@cindex constants
|
|
A constant is a number, written so that its value is known by
|
|
inspection, without knowing any context. Like this:
|
|
@smallexample
|
|
@group
|
|
.byte 74, 0112, 092, 0x4A, 0X4a, 'J, '\J # All the same value.
|
|
.ascii "Ring the bell\7" # A string constant.
|
|
.octa 0x123456789abcdef0123456789ABCDEF0 # A bignum.
|
|
.float 0f-314159265358979323846264338327\
|
|
95028841971.693993751E-40 # - pi, a flonum.
|
|
@end group
|
|
@end smallexample
|
|
|
|
@menu
|
|
* Characters:: Character Constants
|
|
* Numbers:: Number Constants
|
|
@end menu
|
|
|
|
@node Characters
|
|
@subsection Character Constants
|
|
|
|
@cindex character constants
|
|
@cindex constants, character
|
|
There are two kinds of character constants. A @dfn{character} stands
|
|
for one character in one byte and its value may be used in
|
|
numeric expressions. String constants (properly called string
|
|
@emph{literals}) are potentially many bytes and their values may not be
|
|
used in arithmetic expressions.
|
|
|
|
@menu
|
|
* Strings:: Strings
|
|
* Chars:: Characters
|
|
@end menu
|
|
|
|
@node Strings
|
|
@subsubsection Strings
|
|
|
|
@cindex string constants
|
|
@cindex constants, string
|
|
A @dfn{string} is written between double-quotes. It may contain
|
|
double-quotes or null characters. The way to get special characters
|
|
into a string is to @dfn{escape} these characters: precede them with
|
|
a backslash @samp{\} character. For example @samp{\\} represents
|
|
one backslash: the first @code{\} is an escape which tells
|
|
@code{@value{AS}} to interpret the second character literally as a backslash
|
|
(which prevents @code{@value{AS}} from recognizing the second @code{\} as an
|
|
escape character). The complete list of escapes follows.
|
|
|
|
@cindex escape codes, character
|
|
@cindex character escape codes
|
|
@table @kbd
|
|
@c @item \a
|
|
@c Mnemonic for ACKnowledge; for ASCII this is octal code 007.
|
|
@c
|
|
@item \b
|
|
@cindex @code{\b} (backspace character)
|
|
@cindex backspace (@code{\b})
|
|
Mnemonic for backspace; for ASCII this is octal code 010.
|
|
|
|
@c @item \e
|
|
@c Mnemonic for EOText; for ASCII this is octal code 004.
|
|
@c
|
|
@item \f
|
|
@cindex @code{\f} (formfeed character)
|
|
@cindex formfeed (@code{\f})
|
|
Mnemonic for FormFeed; for ASCII this is octal code 014.
|
|
|
|
@item \n
|
|
@cindex @code{\n} (newline character)
|
|
@cindex newline (@code{\n})
|
|
Mnemonic for newline; for ASCII this is octal code 012.
|
|
|
|
@c @item \p
|
|
@c Mnemonic for prefix; for ASCII this is octal code 033, usually known as @code{escape}.
|
|
@c
|
|
@item \r
|
|
@cindex @code{\r} (carriage return character)
|
|
@cindex carriage return (@code{\r})
|
|
Mnemonic for carriage-Return; for ASCII this is octal code 015.
|
|
|
|
@c @item \s
|
|
@c Mnemonic for space; for ASCII this is octal code 040. Included for compliance with
|
|
@c other assemblers.
|
|
@c
|
|
@item \t
|
|
@cindex @code{\t} (tab)
|
|
@cindex tab (@code{\t})
|
|
Mnemonic for horizontal Tab; for ASCII this is octal code 011.
|
|
|
|
@c @item \v
|
|
@c Mnemonic for Vertical tab; for ASCII this is octal code 013.
|
|
@c @item \x @var{digit} @var{digit} @var{digit}
|
|
@c A hexadecimal character code. The numeric code is 3 hexadecimal digits.
|
|
@c
|
|
@item \ @var{digit} @var{digit} @var{digit}
|
|
@cindex @code{\@var{ddd}} (octal character code)
|
|
@cindex octal character code (@code{\@var{ddd}})
|
|
An octal character code. The numeric code is 3 octal digits.
|
|
For compatibility with other Unix systems, 8 and 9 are accepted as digits:
|
|
for example, @code{\008} has the value 010, and @code{\009} the value 011.
|
|
|
|
@item \\
|
|
@cindex @code{\\} (@samp{\} character)
|
|
@cindex backslash (@code{\\})
|
|
Represents one @samp{\} character.
|
|
|
|
@c @item \'
|
|
@c Represents one @samp{'} (accent acute) character.
|
|
@c This is needed in single character literals
|
|
@c (@xref{Characters,,Character Constants}.) to represent
|
|
@c a @samp{'}.
|
|
@c
|
|
@item \"
|
|
@cindex @code{\"} (doublequote character)
|
|
@cindex doublequote (@code{\"})
|
|
Represents one @samp{"} character. Needed in strings to represent
|
|
this character, because an unescaped @samp{"} would end the string.
|
|
|
|
@item \ @var{anything-else}
|
|
Any other character when escaped by @kbd{\} will give a warning, but
|
|
assemble as if the @samp{\} was not present. The idea is that if
|
|
you used an escape sequence you clearly didn't want the literal
|
|
interpretation of the following character. However @code{@value{AS}} has no
|
|
other interpretation, so @code{@value{AS}} knows it is giving you the wrong
|
|
code and warns you of the fact.
|
|
@end table
|
|
|
|
Which characters are escapable, and what those escapes represent,
|
|
varies widely among assemblers. The current set is what we think
|
|
the BSD 4.2 assembler recognizes, and is a subset of what most C
|
|
compilers recognize. If you are in doubt, don't use an escape
|
|
sequence.
|
|
|
|
@node Chars
|
|
@subsubsection Characters
|
|
|
|
@cindex single character constant
|
|
@cindex character, single
|
|
@cindex constant, single character
|
|
A single character may be written as a single quote immediately
|
|
followed by that character. The same escapes apply to characters as
|
|
to strings. So if you want to write the character backslash, you
|
|
must write @kbd{'\\} where the first @code{\} escapes the second
|
|
@code{\}. As you can see, the quote is an acute accent, not a
|
|
grave accent. A newline
|
|
@ifclear GENERIC
|
|
@ifclear abnormal-separator
|
|
(or semicolon @samp{;})
|
|
@end ifclear
|
|
@ifset abnormal-separator
|
|
@ifset A29K
|
|
(or at sign @samp{@@})
|
|
@end ifset
|
|
@ifset H8
|
|
(or dollar sign @samp{$}, for the H8/300; or semicolon @samp{;} for the
|
|
@c start Hitachi-SH
|
|
Hitachi SH or
|
|
@c end Hitachi-SH
|
|
H8/500)
|
|
@end ifset
|
|
@end ifset
|
|
@end ifclear
|
|
immediately following an acute accent is taken as a literal character
|
|
and does not count as the end of a statement. The value of a character
|
|
constant in a numeric expression is the machine's byte-wide code for
|
|
that character. @code{@value{AS}} assumes your character code is ASCII:
|
|
@kbd{'A} means 65, @kbd{'B} means 66, and so on. @refill
|
|
|
|
@node Numbers
|
|
@subsection Number Constants
|
|
|
|
@cindex constants, number
|
|
@cindex number constants
|
|
@code{@value{AS}} distinguishes three kinds of numbers according to how they
|
|
are stored in the target machine. @emph{Integers} are numbers that
|
|
would fit into an @code{int} in the C language. @emph{Bignums} are
|
|
integers, but they are stored in more than 32 bits. @emph{Flonums}
|
|
are floating point numbers, described below.
|
|
|
|
@menu
|
|
* Integers:: Integers
|
|
* Bignums:: Bignums
|
|
* Flonums:: Flonums
|
|
@ifclear GENERIC
|
|
@ifset I960
|
|
* Bit Fields:: Bit Fields
|
|
@end ifset
|
|
@end ifclear
|
|
@end menu
|
|
|
|
@node Integers
|
|
@subsubsection Integers
|
|
@cindex integers
|
|
@cindex constants, integer
|
|
|
|
@cindex binary integers
|
|
@cindex integers, binary
|
|
A binary integer is @samp{0b} or @samp{0B} followed by zero or more of
|
|
the binary digits @samp{01}.
|
|
|
|
@cindex octal integers
|
|
@cindex integers, octal
|
|
An octal integer is @samp{0} followed by zero or more of the octal
|
|
digits (@samp{01234567}).
|
|
|
|
@cindex decimal integers
|
|
@cindex integers, decimal
|
|
A decimal integer starts with a non-zero digit followed by zero or
|
|
more digits (@samp{0123456789}).
|
|
|
|
@cindex hexadecimal integers
|
|
@cindex integers, hexadecimal
|
|
A hexadecimal integer is @samp{0x} or @samp{0X} followed by one or
|
|
more hexadecimal digits chosen from @samp{0123456789abcdefABCDEF}.
|
|
|
|
Integers have the usual values. To denote a negative integer, use
|
|
the prefix operator @samp{-} discussed under expressions
|
|
(@pxref{Prefix Ops,,Prefix Operators}).
|
|
|
|
@node Bignums
|
|
@subsubsection Bignums
|
|
|
|
@cindex bignums
|
|
@cindex constants, bignum
|
|
A @dfn{bignum} has the same syntax and semantics as an integer
|
|
except that the number (or its negative) takes more than 32 bits to
|
|
represent in binary. The distinction is made because in some places
|
|
integers are permitted while bignums are not.
|
|
|
|
@node Flonums
|
|
@subsubsection Flonums
|
|
@cindex flonums
|
|
@cindex floating point numbers
|
|
@cindex constants, floating point
|
|
|
|
@cindex precision, floating point
|
|
A @dfn{flonum} represents a floating point number. The translation is
|
|
indirect: a decimal floating point number from the text is converted by
|
|
@code{@value{AS}} to a generic binary floating point number of more than
|
|
sufficient precision. This generic floating point number is converted
|
|
to a particular computer's floating point format (or formats) by a
|
|
portion of @code{@value{AS}} specialized to that computer.
|
|
|
|
A flonum is written by writing (in order)
|
|
@itemize @bullet
|
|
@item
|
|
The digit @samp{0}.
|
|
|
|
@item
|
|
A letter, to tell @code{@value{AS}} the rest of the number is a flonum.
|
|
@ifset GENERIC
|
|
@kbd{e} is recommended. Case is not important.
|
|
@ignore
|
|
@c FIXME: verify if flonum syntax really this vague for most cases
|
|
(Any otherwise illegal letter
|
|
will work here, but that might be changed. Vax BSD 4.2 assembler seems
|
|
to allow any of @samp{defghDEFGH}.)
|
|
@end ignore
|
|
|
|
On the H8/300, H8/500,
|
|
@c start Hitachi-SH
|
|
Hitachi SH,
|
|
@c end Hitachi-SH
|
|
and AMD 29K architectures, the letter must be
|
|
one of the letters @samp{DFPRSX} (in upper or lower case).
|
|
|
|
On the Intel 960 architecture, the letter must be
|
|
one of the letters @samp{DFT} (in upper or lower case).
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset A29K
|
|
One of the letters @samp{DFPRSX} (in upper or lower case).
|
|
@end ifset
|
|
@ifset H8
|
|
One of the letters @samp{DFPRSX} (in upper or lower case).
|
|
@end ifset
|
|
@ifset I960
|
|
One of the letters @samp{DFT} (in upper or lower case).
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@item
|
|
An optional sign: either @samp{+} or @samp{-}.
|
|
|
|
@item
|
|
An optional @dfn{integer part}: zero or more decimal digits.
|
|
|
|
@item
|
|
An optional @dfn{fractional part}: @samp{.} followed by zero
|
|
or more decimal digits.
|
|
|
|
@item
|
|
An optional exponent, consisting of:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
An @samp{E} or @samp{e}.
|
|
@c I can't find a config where "EXP_CHARS" is other than 'eE', but in
|
|
@c principle this can perfectly well be different on different targets.
|
|
@item
|
|
Optional sign: either @samp{+} or @samp{-}.
|
|
@item
|
|
One or more decimal digits.
|
|
@end itemize
|
|
|
|
@end itemize
|
|
|
|
At least one of the integer part or the fractional part must be
|
|
present. The floating point number has the usual base-10 value.
|
|
|
|
@code{@value{AS}} does all processing using integers. Flonums are computed
|
|
independently of any floating point hardware in the computer running
|
|
@code{@value{AS}}.
|
|
|
|
@ifclear GENERIC
|
|
@ifset I960
|
|
@c Bit fields are written as a general facility but are also controlled
|
|
@c by a conditional-compilation flag---which is as of now (21mar91)
|
|
@c turned on only by the i960 config of GAS.
|
|
@node Bit Fields
|
|
@subsubsection Bit Fields
|
|
|
|
@cindex bit fields
|
|
@cindex constants, bit field
|
|
You can also define numeric constants as @dfn{bit fields}.
|
|
specify two numbers separated by a colon---
|
|
@example
|
|
@var{mask}:@var{value}
|
|
@end example
|
|
@noindent
|
|
the first will act as a mask; @code{@value{AS}} will bitwise-and it with the
|
|
second value.
|
|
|
|
The resulting number is then packed
|
|
@ifset GENERIC
|
|
@c this conditional paren in case bit fields turned on elsewhere than 960
|
|
(in host-dependent byte order)
|
|
@end ifset
|
|
into a field whose width depends on which assembler directive has the
|
|
bit-field as its argument. Overflow (a result from the bitwise and
|
|
requiring more binary digits to represent) is not an error; instead,
|
|
more constants are generated, of the specified width, beginning with the
|
|
least significant digits.@refill
|
|
|
|
The directives @code{.byte}, @code{.hword}, @code{.int}, @code{.long},
|
|
@code{.short}, and @code{.word} accept bit-field arguments.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@node Sections
|
|
@chapter Sections and Relocation
|
|
@cindex sections
|
|
@cindex relocation
|
|
|
|
@menu
|
|
* Secs Background:: Background
|
|
* Ld Sections:: @value{LD} Sections
|
|
* As Sections:: @value{AS} Internal Sections
|
|
* Sub-Sections:: Sub-Sections
|
|
* bss:: bss Section
|
|
@end menu
|
|
|
|
@node Secs Background
|
|
@section Background
|
|
|
|
Roughly, a section is a range of addresses, with no gaps; all data
|
|
``in'' those addresses is treated the same for some particular purpose.
|
|
For example there may be a ``read only'' section.
|
|
|
|
@cindex linker, and assembler
|
|
@cindex assembler, and linker
|
|
The linker @code{@value{LD}} reads many object files (partial programs) and
|
|
combines their contents to form a runnable program. When @code{@value{AS}}
|
|
emits an object file, the partial program is assumed to start at address
|
|
0. @code{@value{LD}} will assign the final addresses the partial program
|
|
occupies, so that different partial programs don't overlap. This is
|
|
actually an over-simplification, but it will suffice to explain how
|
|
@code{@value{AS}} uses sections.
|
|
|
|
@code{@value{LD}} moves blocks of bytes of your program to their run-time
|
|
addresses. These blocks slide to their run-time addresses as rigid
|
|
units; their length does not change and neither does the order of bytes
|
|
within them. Such a rigid unit is called a @emph{section}. Assigning
|
|
run-time addresses to sections is called @dfn{relocation}. It includes
|
|
the task of adjusting mentions of object-file addresses so they refer to
|
|
the proper run-time addresses.
|
|
@ifset H8
|
|
For the H8/300 and H8/500,
|
|
@c start Hitachi-SH
|
|
and for the Hitachi SH,
|
|
@c end Hitachi-SH
|
|
@code{@value{AS}} pads sections if needed to
|
|
ensure they end on a word (sixteen bit) boundary.
|
|
@end ifset
|
|
|
|
@cindex standard @code{@value{AS}} sections
|
|
An object file written by @code{@value{AS}} has at least three sections, any
|
|
of which may be empty. These are named @dfn{text}, @dfn{data} and
|
|
@dfn{bss} sections.
|
|
|
|
@ifset COFF
|
|
@ifset GENERIC
|
|
When it generates COFF output,
|
|
@end ifset
|
|
@code{@value{AS}} can also generate whatever other named sections you specify
|
|
using the @samp{.section} directive (@pxref{Section,,@code{.section}}).
|
|
If you don't use any directives that place output in the @samp{.text}
|
|
or @samp{.data} sections, these sections will still exist, but will be empty.
|
|
@end ifset
|
|
|
|
Within the object file, the text section starts at address @code{0}, the
|
|
data section follows, and the bss section follows the data section.
|
|
|
|
To let @code{@value{LD}} know which data will change when the sections are
|
|
relocated, and how to change that data, @code{@value{AS}} also writes to the
|
|
object file details of the relocation needed. To perform relocation
|
|
@code{@value{LD}} must know, each time an address in the object
|
|
file is mentioned:
|
|
@itemize @bullet
|
|
@item
|
|
Where in the object file is the beginning of this reference to
|
|
an address?
|
|
@item
|
|
How long (in bytes) is this reference?
|
|
@item
|
|
Which section does the address refer to? What is the numeric value of
|
|
@display
|
|
(@var{address}) @minus{} (@var{start-address of section})?
|
|
@end display
|
|
@item
|
|
Is the reference to an address ``Program-Counter relative''?
|
|
@end itemize
|
|
|
|
@cindex addresses, format of
|
|
@cindex section-relative addressing
|
|
In fact, every address @code{@value{AS}} ever uses is expressed as
|
|
@display
|
|
(@var{section}) + (@var{offset into section})
|
|
@end display
|
|
@noindent
|
|
Further, every expression @code{@value{AS}} computes is of this section-relative
|
|
nature. @dfn{Absolute expression} means an expression with section
|
|
``absolute'' (@pxref{Ld Sections}). A @dfn{pass1 expression} means
|
|
an expression with section ``pass1'' (@pxref{As Sections,,@value{AS}
|
|
Internal Sections}). In this manual we use the notation @{@var{secname}
|
|
@var{N}@} to mean ``offset @var{N} into section @var{secname}''.
|
|
|
|
Apart from text, data and bss sections you need to know about the
|
|
@dfn{absolute} section. When @code{@value{LD}} mixes partial programs,
|
|
addresses in the absolute section remain unchanged. For example, address
|
|
@code{@{absolute 0@}} is ``relocated'' to run-time address 0 by @code{@value{LD}}.
|
|
Although two partial programs' data sections will not overlap addresses
|
|
after linking, @emph{by definition} their absolute sections will overlap.
|
|
Address @code{@{absolute@ 239@}} in one partial program will always be the same
|
|
address when the program is running as address @code{@{absolute@ 239@}} in any
|
|
other partial program.
|
|
|
|
The idea of sections is extended to the @dfn{undefined} section. Any
|
|
address whose section is unknown at assembly time is by definition
|
|
rendered @{undefined @var{U}@}---where @var{U} will be filled in later.
|
|
Since numbers are always defined, the only way to generate an undefined
|
|
address is to mention an undefined symbol. A reference to a named
|
|
common block would be such a symbol: its value is unknown at assembly
|
|
time so it has section @emph{undefined}.
|
|
|
|
By analogy the word @emph{section} is used to describe groups of sections in
|
|
the linked program. @code{@value{LD}} puts all partial programs' text
|
|
sections in contiguous addresses in the linked program. It is
|
|
customary to refer to the @emph{text section} of a program, meaning all
|
|
the addresses of all partial program's text sections. Likewise for
|
|
data and bss sections.
|
|
|
|
Some sections are manipulated by @code{@value{LD}}; others are invented for
|
|
use of @code{@value{AS}} and have no meaning except during assembly.
|
|
|
|
@node Ld Sections
|
|
@section @value{LD} Sections
|
|
@code{@value{LD}} deals with just four kinds of sections, summarized below.
|
|
|
|
@table @strong
|
|
|
|
@ifset COFF
|
|
@cindex named sections
|
|
@cindex sections, named
|
|
@item named sections
|
|
@end ifset
|
|
@ifset aout-bout
|
|
@cindex text section
|
|
@cindex data section
|
|
@item text section
|
|
@itemx data section
|
|
@end ifset
|
|
These sections hold your program. @code{@value{AS}} and @code{@value{LD}} treat them as
|
|
separate but equal sections. Anything you can say of one section is
|
|
true another.
|
|
@ifset aout-bout
|
|
When the program is running, however, it is
|
|
customary for the text section to be unalterable. The
|
|
text section is often shared among processes: it will contain
|
|
instructions, constants and the like. The data section of a running
|
|
program is usually alterable: for example, C variables would be stored
|
|
in the data section.
|
|
@end ifset
|
|
|
|
@cindex bss section
|
|
@item bss section
|
|
This section contains zeroed bytes when your program begins running. It
|
|
is used to hold unitialized variables or common storage. The length of
|
|
each partial program's bss section is important, but because it starts
|
|
out containing zeroed bytes there is no need to store explicit zero
|
|
bytes in the object file. The bss section was invented to eliminate
|
|
those explicit zeros from object files.
|
|
|
|
@cindex absolute section
|
|
@item absolute section
|
|
Address 0 of this section is always ``relocated'' to runtime address 0.
|
|
This is useful if you want to refer to an address that @code{@value{LD}} must
|
|
not change when relocating. In this sense we speak of absolute
|
|
addresses being ``unrelocatable'': they don't change during relocation.
|
|
|
|
@cindex undefined section
|
|
@item undefined section
|
|
This ``section'' is a catch-all for address references to objects not in
|
|
the preceding sections.
|
|
@c FIXME: ref to some other doc on obj-file formats could go here.
|
|
@end table
|
|
|
|
@cindex relocation example
|
|
An idealized example of three relocatable sections follows.
|
|
@ifset COFF
|
|
The example uses the traditional section names @samp{.text} and @samp{.data}.
|
|
@end ifset
|
|
Memory addresses are on the horizontal axis.
|
|
|
|
@c TEXI2ROFF-KILL
|
|
@ifinfo
|
|
@c END TEXI2ROFF-KILL
|
|
@smallexample
|
|
+-----+----+--+
|
|
partial program # 1: |ttttt|dddd|00|
|
|
+-----+----+--+
|
|
|
|
text data bss
|
|
seg. seg. seg.
|
|
|
|
+---+---+---+
|
|
partial program # 2: |TTT|DDD|000|
|
|
+---+---+---+
|
|
|
|
+--+---+-----+--+----+---+-----+~~
|
|
linked program: | |TTT|ttttt| |dddd|DDD|00000|
|
|
+--+---+-----+--+----+---+-----+~~
|
|
|
|
addresses: 0 @dots{}
|
|
@end smallexample
|
|
@c TEXI2ROFF-KILL
|
|
@end ifinfo
|
|
@c FIXME make sure no page breaks inside figure!!
|
|
@tex
|
|
|
|
\line{\it Partial program \#1: \hfil}
|
|
\line{\ibox{2.5cm}{\tt text}\ibox{2cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
|
|
\line{\boxit{2.5cm}{\tt ttttt}\boxit{2cm}{\tt dddd}\boxit{1cm}{\tt 00}\hfil}
|
|
|
|
\line{\it Partial program \#2: \hfil}
|
|
\line{\ibox{1cm}{\tt text}\ibox{1.5cm}{\tt data}\ibox{1cm}{\tt bss}\hfil}
|
|
\line{\boxit{1cm}{\tt TTT}\boxit{1.5cm}{\tt DDDD}\boxit{1cm}{\tt 000}\hfil}
|
|
|
|
\line{\it linked program: \hfil}
|
|
\line{\ibox{.5cm}{}\ibox{1cm}{\tt text}\ibox{2.5cm}{}\ibox{.75cm}{}\ibox{2cm}{\tt data}\ibox{1.5cm}{}\ibox{2cm}{\tt bss}\hfil}
|
|
\line{\boxit{.5cm}{}\boxit{1cm}{\tt TTT}\boxit{2.5cm}{\tt
|
|
ttttt}\boxit{.75cm}{}\boxit{2cm}{\tt dddd}\boxit{1.5cm}{\tt
|
|
DDDD}\boxit{2cm}{\tt 00000}\ \dots\hfil}
|
|
|
|
\line{\it addresses: \hfil}
|
|
\line{0\dots\hfil}
|
|
|
|
@end tex
|
|
@c END TEXI2ROFF-KILL
|
|
|
|
@node As Sections
|
|
@section @value{AS} Internal Sections
|
|
|
|
@cindex internal @code{@value{AS}} sections
|
|
@cindex sections in messages, internal
|
|
These sections are meant only for the internal use of @code{@value{AS}}. They
|
|
have no meaning at run-time. You don't really need to know about these
|
|
sections for most purposes; but they can be mentioned in @code{@value{AS}}
|
|
warning messages, so it might be helpful to have an idea of their
|
|
meanings to @code{@value{AS}}. These sections are used to permit the
|
|
value of every expression in your assembly language program to be a
|
|
section-relative address.
|
|
|
|
@table @b
|
|
@item absent
|
|
@cindex absent (internal section)
|
|
An expression was expected and none was found.
|
|
|
|
@item ASSEMBLER-INTERNAL-LOGIC-ERROR!
|
|
@cindex assembler internal logic error
|
|
An internal assembler logic error has been found. This means there is a
|
|
bug in the assembler.
|
|
|
|
@item bignum/flonum
|
|
@cindex bignum/flonum (internal section)
|
|
If a number can't be written as a C @code{int} constant (a bignum or a
|
|
flonum, but not an integer), it is recorded as belonging to this
|
|
``section''. @code{@value{AS}} has to remember that a flonum or a bignum
|
|
does not fit into 32 bits, and cannot be an argument (@pxref{Arguments})
|
|
in an expression: this is done by making a flonum or bignum be in a
|
|
separate internal section. This is purely for internal @code{@value{AS}}
|
|
convenience; bignum/flonum section behaves similarly to absolute
|
|
section.
|
|
|
|
@item pass1 section
|
|
@cindex pass1 (internal section)
|
|
The expression was impossible to evaluate in the first pass. The
|
|
assembler will attempt a second pass (second reading of the source) to
|
|
evaluate the expression. Your expression mentioned an undefined symbol
|
|
in a way that defies the one-pass (section + offset in section) assembly
|
|
process. No compiler need emit such an expression.
|
|
|
|
@quotation
|
|
@emph{Warning:} the second pass is currently not implemented. @code{@value{AS}}
|
|
will abort with an error message if one is required.
|
|
@end quotation
|
|
|
|
@item difference section
|
|
@cindex difference (internal section)
|
|
As an assist to the C compiler, expressions of the forms
|
|
@display
|
|
(@var{undefined symbol}) @minus{} (@var{expression})
|
|
@var{something} @minus{} (@var{undefined symbol})
|
|
(@var{undefined symbol}) @minus{} (@var{undefined symbol})
|
|
@end display
|
|
|
|
are permitted, and belong to the difference section. @code{@value{AS}}
|
|
re-evaluates such expressions after the source file has been read and
|
|
the symbol table built. If by that time there are no undefined symbols
|
|
in the expression then the expression assumes a new section. The
|
|
intention is to permit statements like
|
|
@samp{.word label - base_of_table}
|
|
to be assembled in one pass where both @code{label} and
|
|
@code{base_of_table} are undefined. This is useful for compiling C and
|
|
Algol switch statements, Pascal case statements, FORTRAN computed goto
|
|
statements and the like.
|
|
@c FIXME item debug
|
|
@c FIXME item transfer[t] vector preload
|
|
@c FIXME item transfer[t] vector postload
|
|
@c FIXME item register
|
|
@end table
|
|
|
|
@node Sub-Sections
|
|
@section Sub-Sections
|
|
|
|
@cindex numbered subsections
|
|
@cindex grouping data
|
|
@ifset aout-bout
|
|
Assembled bytes
|
|
@ifset COFF
|
|
conventionally
|
|
@end ifset
|
|
fall into two sections: text and data.
|
|
@end ifset
|
|
You may have separate groups of
|
|
@ifset GENERIC
|
|
data in named sections
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifclear aout-bout
|
|
data in named sections
|
|
@end ifclear
|
|
@ifset aout-bout
|
|
text or data
|
|
@end ifset
|
|
@end ifclear
|
|
that you want to end up near to each other in the object file, even
|
|
though they are not contiguous in the assembler source.
|
|
@code{@value{AS}} allows you to use @dfn{subsections} for this purpose.
|
|
Within each section, there can be numbered subsections with values from
|
|
0 to 8192. Objects assembled into the same subsection will be grouped
|
|
with other objects in the same subsection when they are all put into the
|
|
object file. For example, a compiler might want to store constants in
|
|
the text section, but might not want to have them interspersed with the
|
|
program being assembled. In this case, the compiler could issue a
|
|
@samp{.text 0} before each section of code being output, and a
|
|
@samp{.text 1} before each group of constants being output.
|
|
|
|
Subsections are optional. If you don't use subsections, everything
|
|
will be stored in subsection number zero.
|
|
|
|
@ifset GENERIC
|
|
Each subsection is zero-padded up to a multiple of four bytes.
|
|
(Subsections may be padded a different amount on different flavors
|
|
of @code{@value{AS}}.)
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset H8
|
|
On the H8/300 and H8/500 platforms, each subsection is zero-padded to a word
|
|
boundary (two bytes).
|
|
@c start Hitachi-SH
|
|
The same is true on the Hitachi SH.
|
|
@c end Hitachi-SH
|
|
@end ifset
|
|
@ifset I960
|
|
@c FIXME section padding (alignment)?
|
|
@c Rich Pixley says padding here depends on target obj code format; that
|
|
@c doesn't seem particularly useful to say without further elaboration,
|
|
@c so for now I say nothing about it. If this is a generic BFD issue,
|
|
@c these paragraphs might need to vanish from this manual, and be
|
|
@c discussed in BFD chapter of binutils (or some such).
|
|
@end ifset
|
|
@ifset A29K
|
|
On the AMD 29K family, no particular padding is added to section or
|
|
subsection sizes; @value{AS} forces no alignment on this platform.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
Subsections appear in your object file in numeric order, lowest numbered
|
|
to highest. (All this to be compatible with other people's assemblers.)
|
|
The object file contains no representation of subsections; @code{@value{LD}} and
|
|
other programs that manipulate object files will see no trace of them.
|
|
They just see all your text subsections as a text section, and all your
|
|
data subsections as a data section.
|
|
|
|
To specify which subsection you want subsequent statements assembled
|
|
into, use a numeric argument to specify it, in a @samp{.text
|
|
@var{expression}} or a @samp{.data @var{expression}} statement.
|
|
@ifset COFF
|
|
@ifset GENERIC
|
|
When generating COFF output, you
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
You
|
|
@end ifclear
|
|
can also use an extra subsection
|
|
argument with arbitrary named sections: @samp{.section @var{name},
|
|
@var{expression}}.
|
|
@end ifset
|
|
@var{Expression} should be an absolute expression.
|
|
(@xref{Expressions}.) If you just say @samp{.text} then @samp{.text 0}
|
|
is assumed. Likewise @samp{.data} means @samp{.data 0}. Assembly
|
|
begins in @code{text 0}. For instance:
|
|
@smallexample
|
|
.text 0 # The default subsection is text 0 anyway.
|
|
.ascii "This lives in the first text subsection. *"
|
|
.text 1
|
|
.ascii "But this lives in the second text subsection."
|
|
.data 0
|
|
.ascii "This lives in the data section,"
|
|
.ascii "in the first data subsection."
|
|
.text 0
|
|
.ascii "This lives in the first text section,"
|
|
.ascii "immediately following the asterisk (*)."
|
|
@end smallexample
|
|
|
|
Each section has a @dfn{location counter} incremented by one for every
|
|
byte assembled into that section. Because subsections are merely a
|
|
convenience restricted to @code{@value{AS}} there is no concept of a subsection
|
|
location counter. There is no way to directly manipulate a location
|
|
counter---but the @code{.align} directive will change it, and any label
|
|
definition will capture its current value. The location counter of the
|
|
section that statements are being assembled into is said to be the
|
|
@dfn{active} location counter.
|
|
|
|
@node bss
|
|
@section bss Section
|
|
|
|
@cindex bss section
|
|
@cindex common variable storage
|
|
The bss section is used for local common variable storage.
|
|
You may allocate address space in the bss section, but you may
|
|
not dictate data to load into it before your program executes. When
|
|
your program starts running, all the contents of the bss
|
|
section are zeroed bytes.
|
|
|
|
Addresses in the bss section are allocated with special directives; you
|
|
may not assemble anything directly into the bss section. Hence there
|
|
are no bss subsections. @xref{Comm,,@code{.comm}},
|
|
@pxref{Lcomm,,@code{.lcomm}}.
|
|
|
|
@node Symbols
|
|
@chapter Symbols
|
|
|
|
@cindex symbols
|
|
Symbols are a central concept: the programmer uses symbols to name
|
|
things, the linker uses symbols to link, and the debugger uses symbols
|
|
to debug.
|
|
|
|
@quotation
|
|
@cindex debuggers, and symbol order
|
|
@emph{Warning:} @code{@value{AS}} does not place symbols in the object file in
|
|
the same order they were declared. This may break some debuggers.
|
|
@end quotation
|
|
|
|
@menu
|
|
* Labels:: Labels
|
|
* Setting Symbols:: Giving Symbols Other Values
|
|
* Symbol Names:: Symbol Names
|
|
* Dot:: The Special Dot Symbol
|
|
* Symbol Attributes:: Symbol Attributes
|
|
@end menu
|
|
|
|
@node Labels
|
|
@section Labels
|
|
|
|
@cindex labels
|
|
A @dfn{label} is written as a symbol immediately followed by a colon
|
|
@samp{:}. The symbol then represents the current value of the
|
|
active location counter, and is, for example, a suitable instruction
|
|
operand. You are warned if you use the same symbol to represent two
|
|
different locations: the first definition overrides any other
|
|
definitions.
|
|
|
|
@node Setting Symbols
|
|
@section Giving Symbols Other Values
|
|
|
|
@cindex assigning values to symbols
|
|
@cindex symbol values, assigning
|
|
A symbol can be given an arbitrary value by writing a symbol, followed
|
|
by an equals sign @samp{=}, followed by an expression
|
|
(@pxref{Expressions}). This is equivalent to using the @code{.set}
|
|
directive. @xref{Set,,@code{.set}}.
|
|
|
|
@node Symbol Names
|
|
@section Symbol Names
|
|
|
|
@cindex symbol names
|
|
@cindex names, symbol
|
|
@ifclear SPECIAL-SYMS
|
|
Symbol names begin with a letter or with one of @samp{._}. On most
|
|
machines, you can also use @code{$} in symbol names; exceptions are
|
|
noted in @ref{Machine Dependencies}. That character may be followed by any
|
|
string of digits, letters, dollar signs (unless otherwise noted in
|
|
@ref{Machine Dependencies}), and underscores.
|
|
@end ifclear
|
|
@ifset A29K
|
|
For the AMD 29K family, @samp{?} is also allowed in the
|
|
body of a symbol name, though not at its beginning.
|
|
@end ifset
|
|
|
|
@ifset SPECIAL-SYMS
|
|
@ifset H8
|
|
Symbol names begin with a letter or with one of @samp{._}. On the
|
|
@c start Hitachi-SH
|
|
Hitachi SH or the
|
|
@c end Hitachi-SH
|
|
H8/500, you can also use @code{$} in symbol names. That character may
|
|
be followed by any string of digits, letters, dollar signs (save on the
|
|
H8/300), and underscores.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
Case of letters is significant: @code{foo} is a different symbol name
|
|
than @code{Foo}.
|
|
|
|
Each symbol has exactly one name. Each name in an assembly language
|
|
program refers to exactly one symbol. You may use that symbol name any
|
|
number of times in a program.
|
|
|
|
@subheading Local Symbol Names
|
|
|
|
@cindex local symbol names
|
|
@cindex symbol names, local
|
|
@cindex temporary symbol names
|
|
@cindex symbol names, temporary
|
|
Local symbols help compilers and programmers use names temporarily.
|
|
There are ten local symbol names, which are re-used throughout the
|
|
program. You may refer to them using the names @samp{0} @samp{1}
|
|
@dots{} @samp{9}. To define a local symbol, write a label of the form
|
|
@samp{@b{N}:} (where @b{N} represents any digit). To refer to the most
|
|
recent previous definition of that symbol write @samp{@b{N}b}, using the
|
|
same digit as when you defined the label. To refer to the next
|
|
definition of a local label, write @samp{@b{N}f}---where @b{N} gives you
|
|
a choice of 10 forward references. The @samp{b} stands for
|
|
``backwards'' and the @samp{f} stands for ``forwards''.
|
|
|
|
Local symbols are not emitted by the current GNU C compiler.
|
|
|
|
There is no restriction on how you can use these labels, but
|
|
remember that at any point in the assembly you can refer to at most
|
|
10 prior local labels and to at most 10 forward local labels.
|
|
|
|
Local symbol names are only a notation device. They are immediately
|
|
transformed into more conventional symbol names before the assembler
|
|
uses them. The symbol names stored in the symbol table, appearing in
|
|
error messages and optionally emitted to the object file have these
|
|
parts:
|
|
|
|
@table @code
|
|
@item L
|
|
All local labels begin with @samp{L}. Normally both @code{@value{AS}} and
|
|
@code{@value{LD}} forget symbols that start with @samp{L}. These labels are
|
|
used for symbols you are never intended to see. If you give the
|
|
@samp{-L} option then @code{@value{AS}} will retain these symbols in the
|
|
object file. If you also instruct @code{@value{LD}} to retain these symbols,
|
|
you may use them in debugging.
|
|
|
|
@item @var{digit}
|
|
If the label is written @samp{0:} then the digit is @samp{0}.
|
|
If the label is written @samp{1:} then the digit is @samp{1}.
|
|
And so on up through @samp{9:}.
|
|
|
|
@item @ctrl{A}
|
|
This unusual character is included so you don't accidentally invent
|
|
a symbol of the same name. The character has ASCII value
|
|
@samp{\001}.
|
|
|
|
@item @emph{ordinal number}
|
|
This is a serial number to keep the labels distinct. The first
|
|
@samp{0:} gets the number @samp{1}; The 15th @samp{0:} gets the
|
|
number @samp{15}; @emph{etc.}. Likewise for the other labels @samp{1:}
|
|
through @samp{9:}.
|
|
@end table
|
|
|
|
For instance, the first @code{1:} is named @code{L1@ctrl{A}1}, the 44th
|
|
@code{3:} is named @code{L3@ctrl{A}44}.
|
|
|
|
@node Dot
|
|
@section The Special Dot Symbol
|
|
|
|
@cindex dot (symbol)
|
|
@cindex @code{.} (symbol)
|
|
@cindex current address
|
|
@cindex location counter
|
|
The special symbol @samp{.} refers to the current address that
|
|
@code{@value{AS}} is assembling into. Thus, the expression @samp{melvin:
|
|
.long .} will cause @code{melvin} to contain its own address.
|
|
Assigning a value to @code{.} is treated the same as a @code{.org}
|
|
directive. Thus, the expression @samp{.=.+4} is the same as saying
|
|
@ifclear no-space-dir
|
|
@samp{.space 4}.
|
|
@end ifclear
|
|
@ifset no-space-dir
|
|
@ifset A29K
|
|
@samp{.block 4}.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@node Symbol Attributes
|
|
@section Symbol Attributes
|
|
|
|
@cindex symbol attributes
|
|
@cindex attributes, symbol
|
|
Every symbol has, as well as its name, the attributes ``Value'' and
|
|
``Type''. Depending on output format, symbols can also have auxiliary
|
|
attributes.
|
|
@ifset INTERNALS
|
|
The detailed definitions are in @file{a.out.h}.
|
|
@end ifset
|
|
|
|
If you use a symbol without defining it, @code{@value{AS}} assumes zero for
|
|
all these attributes, and probably won't warn you. This makes the
|
|
symbol an externally defined symbol, which is generally what you
|
|
would want.
|
|
|
|
@menu
|
|
* Symbol Value:: Value
|
|
* Symbol Type:: Type
|
|
@ifset aout-bout
|
|
@ifset GENERIC
|
|
* a.out Symbols:: Symbol Attributes: @code{a.out}
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifclear BOUT
|
|
* a.out Symbols:: Symbol Attributes: @code{a.out}
|
|
@end ifclear
|
|
@ifset BOUT
|
|
* a.out Symbols:: Symbol Attributes: @code{a.out}, @code{b.out}
|
|
@end ifset
|
|
@end ifclear
|
|
@end ifset
|
|
@ifset COFF
|
|
* COFF Symbols:: Symbol Attributes for COFF
|
|
@end ifset
|
|
@end menu
|
|
|
|
@node Symbol Value
|
|
@subsection Value
|
|
|
|
@cindex value of a symbol
|
|
@cindex symbol value
|
|
The value of a symbol is (usually) 32 bits. For a symbol which labels a
|
|
location in the text, data, bss or absolute sections the value is the
|
|
number of addresses from the start of that section to the label.
|
|
Naturally for text, data and bss sections the value of a symbol changes
|
|
as @code{@value{LD}} changes section base addresses during linking. Absolute
|
|
symbols' values do not change during linking: that is why they are
|
|
called absolute.
|
|
|
|
The value of an undefined symbol is treated in a special way. If it is
|
|
0 then the symbol is not defined in this assembler source program, and
|
|
@code{@value{LD}} will try to determine its value from other programs it is
|
|
linked with. You make this kind of symbol simply by mentioning a symbol
|
|
name without defining it. A non-zero value represents a @code{.comm}
|
|
common declaration. The value is how much common storage to reserve, in
|
|
bytes (addresses). The symbol refers to the first address of the
|
|
allocated storage.
|
|
|
|
@node Symbol Type
|
|
@subsection Type
|
|
|
|
@cindex type of a symbol
|
|
@cindex symbol type
|
|
The type attribute of a symbol contains relocation (section)
|
|
information, any flag settings indicating that a symbol is external, and
|
|
(optionally), other information for linkers and debuggers. The exact
|
|
format depends on the object-code output format in use.
|
|
|
|
@ifset aout-bout
|
|
@ifclear GENERIC
|
|
@ifset BOUT
|
|
@c The following avoids a "widow" subsection title. @group would be
|
|
@c better if it were available outside examples.
|
|
@need 1000
|
|
@node a.out Symbols
|
|
@subsection Symbol Attributes: @code{a.out}, @code{b.out}
|
|
|
|
@cindex @code{b.out} symbol attributes
|
|
@cindex symbol attributes, @code{b.out}
|
|
These symbol attributes appear only when @code{@value{AS}} is configured for
|
|
one of the Berkeley-descended object output formats---@code{a.out} or
|
|
@code{b.out}.
|
|
|
|
@end ifset
|
|
@ifclear BOUT
|
|
@node a.out Symbols
|
|
@subsection Symbol Attributes: @code{a.out}
|
|
|
|
@cindex @code{a.out} symbol attributes
|
|
@cindex symbol attributes, @code{a.out}
|
|
|
|
@end ifclear
|
|
@end ifclear
|
|
@ifset GENERIC
|
|
@node a.out Symbols
|
|
@subsection Symbol Attributes: @code{a.out}
|
|
|
|
@cindex @code{a.out} symbol attributes
|
|
@cindex symbol attributes, @code{a.out}
|
|
|
|
@end ifset
|
|
@menu
|
|
* Symbol Desc:: Descriptor
|
|
* Symbol Other:: Other
|
|
@end menu
|
|
|
|
@node Symbol Desc
|
|
@subsubsection Descriptor
|
|
|
|
@cindex descriptor, of @code{a.out} symbol
|
|
This is an arbitrary 16-bit value. You may establish a symbol's
|
|
descriptor value by using a @code{.desc} statement
|
|
(@pxref{Desc,,@code{.desc}}). A descriptor value means nothing to
|
|
@code{@value{AS}}.
|
|
|
|
@node Symbol Other
|
|
@subsubsection Other
|
|
|
|
@cindex other attribute, of @code{a.out} symbol
|
|
This is an arbitrary 8-bit value. It means nothing to @code{@value{AS}}.
|
|
@end ifset
|
|
|
|
@ifset COFF
|
|
@node COFF Symbols
|
|
@subsection Symbol Attributes for COFF
|
|
|
|
@cindex COFF symbol attributes
|
|
@cindex symbol attributes, COFF
|
|
|
|
The COFF format supports a multitude of auxiliary symbol attributes;
|
|
like the primary symbol attributes, they are set between @code{.def} and
|
|
@code{.endef} directives.
|
|
|
|
@subsubsection Primary Attributes
|
|
|
|
@cindex primary attributes, COFF symbols
|
|
The symbol name is set with @code{.def}; the value and type,
|
|
respectively, with @code{.val} and @code{.type}.
|
|
|
|
@subsubsection Auxiliary Attributes
|
|
|
|
@cindex auxiliary attributes, COFF symbols
|
|
The @code{@value{AS}} directives @code{.dim}, @code{.line}, @code{.scl},
|
|
@code{.size}, and @code{.tag} can generate auxiliary symbol table
|
|
information for COFF.
|
|
@end ifset
|
|
|
|
@node Expressions
|
|
@chapter Expressions
|
|
|
|
@cindex expressions
|
|
@cindex addresses
|
|
@cindex numeric values
|
|
An @dfn{expression} specifies an address or numeric value.
|
|
Whitespace may precede and/or follow an expression.
|
|
|
|
@menu
|
|
* Empty Exprs:: Empty Expressions
|
|
* Integer Exprs:: Integer Expressions
|
|
@end menu
|
|
|
|
@node Empty Exprs
|
|
@section Empty Expressions
|
|
|
|
@cindex empty expressions
|
|
@cindex expressions, empty
|
|
An empty expression has no value: it is just whitespace or null.
|
|
Wherever an absolute expression is required, you may omit the
|
|
expression and @code{@value{AS}} will assume a value of (absolute) 0. This
|
|
is compatible with other assemblers.
|
|
|
|
@node Integer Exprs
|
|
@section Integer Expressions
|
|
|
|
@cindex integer expressions
|
|
@cindex expressions, integer
|
|
An @dfn{integer expression} is one or more @emph{arguments} delimited
|
|
by @emph{operators}.
|
|
|
|
@menu
|
|
* Arguments:: Arguments
|
|
* Operators:: Operators
|
|
* Prefix Ops:: Prefix Operators
|
|
* Infix Ops:: Infix Operators
|
|
@end menu
|
|
|
|
@node Arguments
|
|
@subsection Arguments
|
|
|
|
@cindex expression arguments
|
|
@cindex arguments in expressions
|
|
@cindex operands in expressions
|
|
@cindex arithmetic operands
|
|
@dfn{Arguments} are symbols, numbers or subexpressions. In other
|
|
contexts arguments are sometimes called ``arithmetic operands''. In
|
|
this manual, to avoid confusing them with the ``instruction operands'' of
|
|
the machine language, we use the term ``argument'' to refer to parts of
|
|
expressions only, reserving the word ``operand'' to refer only to machine
|
|
instruction operands.
|
|
|
|
Symbols are evaluated to yield @{@var{section} @var{NNN}@} where
|
|
@var{section} is one of text, data, bss, absolute,
|
|
or undefined. @var{NNN} is a signed, 2's complement 32 bit
|
|
integer.
|
|
|
|
Numbers are usually integers.
|
|
|
|
A number can be a flonum or bignum. In this case, you are warned
|
|
that only the low order 32 bits are used, and @code{@value{AS}} pretends
|
|
these 32 bits are an integer. You may write integer-manipulating
|
|
instructions that act on exotic constants, compatible with other
|
|
assemblers.
|
|
|
|
@cindex subexpressions
|
|
Subexpressions are a left parenthesis @samp{(} followed by an integer
|
|
expression, followed by a right parenthesis @samp{)}; or a prefix
|
|
operator followed by an argument.
|
|
|
|
@node Operators
|
|
@subsection Operators
|
|
|
|
@cindex operators, in expressions
|
|
@cindex arithmetic functions
|
|
@cindex functions, in expressions
|
|
@dfn{Operators} are arithmetic functions, like @code{+} or @code{%}. Prefix
|
|
operators are followed by an argument. Infix operators appear
|
|
between their arguments. Operators may be preceded and/or followed by
|
|
whitespace.
|
|
|
|
@node Prefix Ops
|
|
@subsection Prefix Operator
|
|
|
|
@cindex prefix operators
|
|
@code{@value{AS}} has the following @dfn{prefix operators}. They each take
|
|
one argument, which must be absolute.
|
|
|
|
@c the tex/end tex stuff surrounding this small table is meant to make
|
|
@c it align, on the printed page, with the similar table in the next
|
|
@c section (which is inside an enumerate).
|
|
@tex
|
|
\global\advance\leftskip by \itemindent
|
|
@end tex
|
|
|
|
@table @code
|
|
@item -
|
|
@dfn{Negation}. Two's complement negation.
|
|
@item ~
|
|
@dfn{Complementation}. Bitwise not.
|
|
@end table
|
|
|
|
@tex
|
|
\global\advance\leftskip by -\itemindent
|
|
@end tex
|
|
|
|
@node Infix Ops
|
|
@subsection Infix Operators
|
|
|
|
@cindex infix operators
|
|
@cindex operators, permitted arguments
|
|
@dfn{Infix operators} take two arguments, one on either side. Operators
|
|
have precedence, but operations with equal precedence are performed left
|
|
to right. Apart from @code{+} or @code{-}, both arguments must be
|
|
absolute, and the result is absolute.
|
|
|
|
@enumerate
|
|
@cindex operator precedence
|
|
@cindex precedence of operators
|
|
|
|
@item
|
|
Highest Precedence
|
|
|
|
@table @code
|
|
@item *
|
|
@dfn{Multiplication}.
|
|
|
|
@item /
|
|
@dfn{Division}. Truncation is the same as the C operator @samp{/}
|
|
|
|
@item %
|
|
@dfn{Remainder}.
|
|
|
|
@item <
|
|
@itemx <<
|
|
@dfn{Shift Left}. Same as the C operator @samp{<<}.
|
|
|
|
@item >
|
|
@itemx >>
|
|
@dfn{Shift Right}. Same as the C operator @samp{>>}.
|
|
@end table
|
|
|
|
@item
|
|
Intermediate precedence
|
|
|
|
@table @code
|
|
@item |
|
|
|
|
@dfn{Bitwise Inclusive Or}.
|
|
|
|
@item &
|
|
@dfn{Bitwise And}.
|
|
|
|
@item ^
|
|
@dfn{Bitwise Exclusive Or}.
|
|
|
|
@item !
|
|
@dfn{Bitwise Or Not}.
|
|
@end table
|
|
|
|
@item
|
|
Lowest Precedence
|
|
|
|
@table @code
|
|
@item +
|
|
@cindex addition, permitted arguments
|
|
@cindex plus, permitted arguments
|
|
@cindex arguments for addition
|
|
@dfn{Addition}. If either argument is absolute, the result
|
|
has the section of the other argument.
|
|
If either argument is pass1 or undefined, the result is pass1.
|
|
Otherwise @code{+} is illegal.
|
|
|
|
@item -
|
|
@cindex subtraction, permitted arguments
|
|
@cindex minus, permitted arguments
|
|
@cindex arguments for subtraction
|
|
@dfn{Subtraction}. If the right argument is absolute, the
|
|
result has the section of the left argument.
|
|
If either argument is pass1 the result is pass1.
|
|
If either argument is undefined the result is difference section.
|
|
If both arguments are in the same section, the result is absolute---provided
|
|
that section is one of text, data or bss.
|
|
Otherwise subtraction is illegal.
|
|
@end table
|
|
@end enumerate
|
|
|
|
The sense of the rule for addition is that it's only meaningful to add
|
|
the @emph{offsets} in an address; you can only have a defined section in
|
|
one of the two arguments.
|
|
|
|
Similarly, you can't subtract quantities from two different sections.
|
|
|
|
@node Pseudo Ops
|
|
@chapter Assembler Directives
|
|
|
|
@cindex directives, machine independent
|
|
@cindex pseudo-ops, machine independent
|
|
@cindex machine independent directives
|
|
All assembler directives have names that begin with a period (@samp{.}).
|
|
The rest of the name is letters, usually in lower case.
|
|
|
|
This chapter discusses directives that are available regardless of the
|
|
target machine configuration for the GNU assembler.
|
|
@ifset GENERIC
|
|
Some machine configurations provide additional directives.
|
|
@xref{Machine Dependencies}.
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset machine-directives
|
|
@xref{Machine Dependencies} for additional directives.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@menu
|
|
* Abort:: @code{.abort}
|
|
@ifset COFF
|
|
* ABORT:: @code{.ABORT}
|
|
@end ifset
|
|
|
|
* Align:: @code{.align @var{abs-expr} , @var{abs-expr}}
|
|
* App-File:: @code{.app-file @var{string}}
|
|
* Ascii:: @code{.ascii "@var{string}"}@dots{}
|
|
* Asciz:: @code{.asciz "@var{string}"}@dots{}
|
|
* Byte:: @code{.byte @var{expressions}}
|
|
* Comm:: @code{.comm @var{symbol} , @var{length} }
|
|
* Data:: @code{.data @var{subsection}}
|
|
@ifset COFF
|
|
* Def:: @code{.def @var{name}}
|
|
@end ifset
|
|
@ifset aout-bout
|
|
* Desc:: @code{.desc @var{symbol}, @var{abs-expression}}
|
|
@end ifset
|
|
@ifset COFF
|
|
* Dim:: @code{.dim}
|
|
@end ifset
|
|
|
|
* Double:: @code{.double @var{flonums}}
|
|
* Eject:: @code{.eject}
|
|
* Else:: @code{.else}
|
|
@ifset COFF
|
|
* Endef:: @code{.endef}
|
|
@end ifset
|
|
|
|
* Endif:: @code{.endif}
|
|
* Equ:: @code{.equ @var{symbol}, @var{expression}}
|
|
* Extern:: @code{.extern}
|
|
@ifclear no-file-dir
|
|
* File:: @code{.file @var{string}}
|
|
@end ifclear
|
|
|
|
* Fill:: @code{.fill @var{repeat} , @var{size} , @var{value}}
|
|
* Float:: @code{.float @var{flonums}}
|
|
* Global:: @code{.global @var{symbol}}, @code{.globl @var{symbol}}
|
|
* hword:: @code{.hword @var{expressions}}
|
|
* Ident:: @code{.ident}
|
|
* If:: @code{.if @var{absolute expression}}
|
|
* Include:: @code{.include "@var{file}"}
|
|
* Int:: @code{.int @var{expressions}}
|
|
* Lcomm:: @code{.lcomm @var{symbol} , @var{length}}
|
|
* Lflags:: @code{.lflags}
|
|
@ifclear no-line-dir
|
|
* Line:: @code{.line @var{line-number}}
|
|
@end ifclear
|
|
|
|
* Ln:: @code{.ln @var{line-number}}
|
|
* List:: @code{.list}
|
|
* Long:: @code{.long @var{expressions}}
|
|
@ignore
|
|
* Lsym:: @code{.lsym @var{symbol}, @var{expression}}
|
|
@end ignore
|
|
|
|
* Nolist:: @code{.nolist}
|
|
* Octa:: @code{.octa @var{bignums}}
|
|
* Org:: @code{.org @var{new-lc} , @var{fill}}
|
|
* Psize:: @code{.psize @var{lines}, @var{columns}}
|
|
* Quad:: @code{.quad @var{bignums}}
|
|
* Sbttl:: @code{.sbttl "@var{subheading}"}
|
|
@ifset COFF
|
|
* Scl:: @code{.scl @var{class}}
|
|
@end ifset
|
|
@ifset COFF
|
|
* Section:: @code{.section @var{name}, @var{subsection}}
|
|
@end ifset
|
|
|
|
* Set:: @code{.set @var{symbol}, @var{expression}}
|
|
* Short:: @code{.short @var{expressions}}
|
|
* Single:: @code{.single @var{flonums}}
|
|
@ifset COFF
|
|
* Size:: @code{.size}
|
|
@end ifset
|
|
|
|
* Space:: @code{.space @var{size} , @var{fill}}
|
|
@ifset have-stabs
|
|
* Stab:: @code{.stabd, .stabn, .stabs}
|
|
@end ifset
|
|
@ifset COFF
|
|
* Tag:: @code{.tag @var{structname}}
|
|
@end ifset
|
|
|
|
* Text:: @code{.text @var{subsection}}
|
|
* Title:: @code{.title "@var{heading}"}
|
|
@ifset COFF
|
|
* Type:: @code{.type @var{int}}
|
|
* Val:: @code{.val @var{addr}}
|
|
@end ifset
|
|
|
|
* Word:: @code{.word @var{expressions}}
|
|
* Deprecated:: Deprecated Directives
|
|
@end menu
|
|
|
|
@node Abort
|
|
@section @code{.abort}
|
|
|
|
@cindex @code{abort} directive
|
|
@cindex stopping the assembly
|
|
This directive stops the assembly immediately. It is for
|
|
compatibility with other assemblers. The original idea was that the
|
|
assembly language source would be piped into the assembler. If the sender
|
|
of the source quit, it could use this directive tells @code{@value{AS}} to
|
|
quit also. One day @code{.abort} will not be supported.
|
|
|
|
@ifset COFF
|
|
@node ABORT
|
|
@section @code{.ABORT}
|
|
|
|
@cindex @code{ABORT} directive
|
|
When producing COFF output, @code{@value{AS}} accepts this directive as a
|
|
synonym for @samp{.abort}.
|
|
|
|
@ifset BOUT
|
|
When producing @code{b.out} output, @code{@value{AS}} accepts this directive,
|
|
but ignores it.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@node Align
|
|
@section @code{.align @var{abs-expr} , @var{abs-expr}}
|
|
|
|
@cindex padding the location counter
|
|
@cindex @code{align} directive
|
|
Pad the location counter (in the current subsection) to a particular
|
|
storage boundary. The first expression (which must be absolute) is the
|
|
number of low-order zero bits the location counter will have after
|
|
advancement. For example @samp{.align 3} will advance the location
|
|
counter until it a multiple of 8. If the location counter is already a
|
|
multiple of 8, no change is needed.
|
|
|
|
The second expression (also absolute) gives the value to be stored in
|
|
the padding bytes. It (and the comma) may be omitted. If it is
|
|
omitted, the padding bytes are zero.
|
|
|
|
@node App-File
|
|
@section @code{.app-file @var{string}}
|
|
|
|
@cindex logical file name
|
|
@cindex file name, logical
|
|
@cindex @code{app-file} directive
|
|
@code{.app-file}
|
|
@ifclear no-file-dir
|
|
(which may also be spelled @samp{.file})
|
|
@end ifclear
|
|
tells @code{@value{AS}} that we are about to start a new
|
|
logical file. @var{string} is the new file name. In general, the
|
|
filename is recognized whether or not it is surrounded by quotes @samp{"};
|
|
but if you wish to specify an empty file name is permitted,
|
|
you must give the quotes--@code{""}. This statement may go away in
|
|
future: it is only recognized to be compatible with old @code{@value{AS}}
|
|
programs.@refill
|
|
|
|
@node Ascii
|
|
@section @code{.ascii "@var{string}"}@dots{}
|
|
|
|
@cindex @code{ascii} directive
|
|
@cindex string literals
|
|
@code{.ascii} expects zero or more string literals (@pxref{Strings})
|
|
separated by commas. It assembles each string (with no automatic
|
|
trailing zero byte) into consecutive addresses.
|
|
|
|
@node Asciz
|
|
@section @code{.asciz "@var{string}"}@dots{}
|
|
|
|
@cindex @code{asciz} directive
|
|
@cindex zero-terminated strings
|
|
@cindex null-terminated strings
|
|
@code{.asciz} is just like @code{.ascii}, but each string is followed by
|
|
a zero byte. The ``z'' in @samp{.asciz} stands for ``zero''.
|
|
|
|
@node Byte
|
|
@section @code{.byte @var{expressions}}
|
|
|
|
@cindex @code{byte} directive
|
|
@cindex integers, one byte
|
|
@code{.byte} expects zero or more expressions, separated by commas.
|
|
Each expression is assembled into the next byte.
|
|
|
|
@node Comm
|
|
@section @code{.comm @var{symbol} , @var{length} }
|
|
|
|
@cindex @code{comm} directive
|
|
@cindex symbol, common
|
|
@code{.comm} declares a named common area in the bss section. Normally
|
|
@code{@value{LD}} reserves memory addresses for it during linking, so no partial
|
|
program defines the location of the symbol. Use @code{.comm} to tell
|
|
@code{@value{LD}} that it must be at least @var{length} bytes long. @code{@value{LD}}
|
|
will allocate space for each @code{.comm} symbol that is at least as
|
|
long as the longest @code{.comm} request in any of the partial programs
|
|
linked. @var{length} is an absolute expression.
|
|
|
|
@node Data
|
|
@section @code{.data @var{subsection}}
|
|
|
|
@cindex @code{data} directive
|
|
@code{.data} tells @code{@value{AS}} to assemble the following statements onto the
|
|
end of the data subsection numbered @var{subsection} (which is an
|
|
absolute expression). If @var{subsection} is omitted, it defaults
|
|
to zero.
|
|
|
|
@ifset COFF
|
|
@node Def
|
|
@section @code{.def @var{name}}
|
|
|
|
@cindex @code{def} directive
|
|
@cindex COFF symbols, debugging
|
|
@cindex debugging COFF symbols
|
|
Begin defining debugging information for a symbol @var{name}; the
|
|
definition extends until the @code{.endef} directive is encountered.
|
|
@ifset BOUT
|
|
|
|
This directive is only observed when @code{@value{AS}} is configured for COFF
|
|
format output; when producing @code{b.out}, @samp{.def} is recognized,
|
|
but ignored.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@ifset aout-bout
|
|
@node Desc
|
|
@section @code{.desc @var{symbol}, @var{abs-expression}}
|
|
|
|
@cindex @code{desc} directive
|
|
@cindex COFF symbol descriptor
|
|
@cindex symbol descriptor, COFF
|
|
This directive sets the descriptor of the symbol (@pxref{Symbol Attributes})
|
|
to the low 16 bits of an absolute expression.
|
|
|
|
@ifset COFF
|
|
The @samp{.desc} directive is not available when @code{@value{AS}} is
|
|
configured for COFF output; it is only for @code{a.out} or @code{b.out}
|
|
object format. For the sake of compatibility, @code{@value{AS}} will accept
|
|
it, but produce no output, when configured for COFF.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@ifset COFF
|
|
@node Dim
|
|
@section @code{.dim}
|
|
|
|
@cindex @code{dim} directive
|
|
@cindex COFF auxiliary symbol information
|
|
@cindex auxiliary symbol information, COFF
|
|
This directive is generated by compilers to include auxiliary debugging
|
|
information in the symbol table. It is only permitted inside
|
|
@code{.def}/@code{.endef} pairs.
|
|
@ifset BOUT
|
|
|
|
@samp{.dim} is only meaningful when generating COFF format output; when
|
|
@code{@value{AS}} is generating @code{b.out}, it accepts this directive but
|
|
ignores it.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@node Double
|
|
@section @code{.double @var{flonums}}
|
|
|
|
@cindex @code{double} directive
|
|
@cindex floating point numbers (double)
|
|
@code{.double} expects zero or more flonums, separated by commas. It
|
|
assembles floating point numbers.
|
|
@ifset GENERIC
|
|
The exact kind of floating point numbers emitted depends on how
|
|
@code{@value{AS}} is configured. @xref{Machine Dependencies}.
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset IEEEFLOAT
|
|
On the @value{TARGET} family @samp{.double} emits 64-bit floating-point numbers
|
|
in @sc{ieee} format.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@node Eject
|
|
@section @code{.eject}
|
|
|
|
@cindex @code{eject} directive
|
|
@cindex new page, in listings
|
|
@cindex page, in listings
|
|
@cindex listing control: new page
|
|
Force a page break at this point, when generating assembly listings.
|
|
|
|
@node Else
|
|
@section @code{.else}
|
|
|
|
@cindex @code{else} directive
|
|
@code{.else} is part of the @code{@value{AS}} support for conditional
|
|
assembly; @pxref{If,,@code{.if}}. It marks the beginning of a section
|
|
of code to be assembled if the condition for the preceding @code{.if}
|
|
was false.
|
|
|
|
@ignore
|
|
@node End, Endef, Else, Pseudo Ops
|
|
@section @code{.end}
|
|
|
|
@cindex @code{end} directive
|
|
This doesn't do anything---but isn't an s_ignore, so I suspect it's
|
|
meant to do something eventually (which is why it isn't documented here
|
|
as "for compatibility with blah").
|
|
@end ignore
|
|
|
|
@ifset COFF
|
|
@node Endef
|
|
@section @code{.endef}
|
|
|
|
@cindex @code{endef} directive
|
|
This directive flags the end of a symbol definition begun with
|
|
@code{.def}.
|
|
@ifset BOUT
|
|
|
|
@samp{.endef} is only meaningful when generating COFF format output; if
|
|
@code{@value{AS}} is configured to generate @code{b.out}, it accepts this
|
|
directive but ignores it.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@node Endif
|
|
@section @code{.endif}
|
|
|
|
@cindex @code{endif} directive
|
|
@code{.endif} is part of the @code{@value{AS}} support for conditional assembly;
|
|
it marks the end of a block of code that is only assembled
|
|
conditionally. @xref{If,,@code{.if}}.
|
|
|
|
@node Equ
|
|
@section @code{.equ @var{symbol}, @var{expression}}
|
|
|
|
@cindex @code{equ} directive
|
|
@cindex assigning values to symbols
|
|
@cindex symbols, assigning values to
|
|
This directive sets the value of @var{symbol} to @var{expression}.
|
|
It is synonymous with @samp{.set}; @pxref{Set,,@code{.set}}.
|
|
|
|
@node Extern
|
|
@section @code{.extern}
|
|
|
|
@cindex @code{extern} directive
|
|
@code{.extern} is accepted in the source program---for compatibility
|
|
with other assemblers---but it is ignored. @code{@value{AS}} treats
|
|
all undefined symbols as external.
|
|
|
|
@ifclear no-file-dir
|
|
@node File
|
|
@section @code{.file @var{string}}
|
|
|
|
@cindex @code{file} directive
|
|
@cindex logical file name
|
|
@cindex file name, logical
|
|
@code{.file} (which may also be spelled @samp{.app-file}) tells
|
|
@code{@value{AS}} that we are about to start a new logical file.
|
|
@var{string} is the new file name. In general, the filename is
|
|
recognized whether or not it is surrounded by quotes @samp{"}; but if
|
|
you wish to specify an empty file name, you must give the
|
|
quotes--@code{""}. This statement may go away in future: it is only
|
|
recognized to be compatible with old @code{@value{AS}} programs.
|
|
@ifset A29K
|
|
In some configurations of @code{@value{AS}}, @code{.file} has already been
|
|
removed to avoid conflicts with other assemblers. @xref{Machine Dependencies}.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@node Fill
|
|
@section @code{.fill @var{repeat} , @var{size} , @var{value}}
|
|
|
|
@cindex @code{fill} directive
|
|
@cindex writing patterns in memory
|
|
@cindex patterns, writing in memory
|
|
@var{result}, @var{size} and @var{value} are absolute expressions.
|
|
This emits @var{repeat} copies of @var{size} bytes. @var{Repeat}
|
|
may be zero or more. @var{Size} may be zero or more, but if it is
|
|
more than 8, then it is deemed to have the value 8, compatible with
|
|
other people's assemblers. The contents of each @var{repeat} bytes
|
|
is taken from an 8-byte number. The highest order 4 bytes are
|
|
zero. The lowest order 4 bytes are @var{value} rendered in the
|
|
byte-order of an integer on the computer @code{@value{AS}} is assembling for.
|
|
Each @var{size} bytes in a repetition is taken from the lowest order
|
|
@var{size} bytes of this number. Again, this bizarre behavior is
|
|
compatible with other people's assemblers.
|
|
|
|
@var{size} and @var{value} are optional.
|
|
If the second comma and @var{value} are absent, @var{value} is
|
|
assumed zero. If the first comma and following tokens are absent,
|
|
@var{size} is assumed to be 1.
|
|
|
|
@node Float
|
|
@section @code{.float @var{flonums}}
|
|
|
|
@cindex floating point numbers (single)
|
|
@cindex @code{float} directive
|
|
This directive assembles zero or more flonums, separated by commas. It
|
|
has the same effect as @code{.single}.
|
|
@ifset GENERIC
|
|
The exact kind of floating point numbers emitted depends on how
|
|
@code{@value{AS}} is configured.
|
|
@xref{Machine Dependencies}.
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset IEEEFLOAT
|
|
On the @value{TARGET} family, @code{.float} emits 32-bit floating point numbers
|
|
in @sc{ieee} format.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@node Global
|
|
@section @code{.global @var{symbol}}, @code{.globl @var{symbol}}
|
|
|
|
@cindex @code{global} directive
|
|
@cindex symbol, making visible to linker
|
|
@code{.global} makes the symbol visible to @code{@value{LD}}. If you define
|
|
@var{symbol} in your partial program, its value is made available to
|
|
other partial programs that are linked with it. Otherwise,
|
|
@var{symbol} will take its attributes from a symbol of the same name
|
|
from another partial program it is linked with.
|
|
|
|
Both spellings (@samp{.globl} and @samp{.global}) are accepted, for
|
|
compatibility with other assemblers.
|
|
|
|
@node hword
|
|
@section @code{.hword @var{expressions}}
|
|
|
|
@cindex @code{hword} directive
|
|
@cindex integers, 16-bit
|
|
@cindex numbers, 16-bit
|
|
@cindex sixteen bit integers
|
|
This expects zero or more @var{expressions}, and emits
|
|
a 16 bit number for each.
|
|
|
|
@ifset GENERIC
|
|
This directive is a synonym for @samp{.short}; depending on the target
|
|
architecture, it may also be a synonym for @samp{.word}.
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset W32
|
|
This directive is a synonym for @samp{.short}.
|
|
@end ifset
|
|
@ifset W16
|
|
This directive is a synonym for both @samp{.short} and @samp{.word}.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@node Ident
|
|
@section @code{.ident}
|
|
|
|
@cindex @code{ident} directive
|
|
This directive is used by some assemblers to place tags in object files.
|
|
@code{@value{AS}} simply accepts the directive for source-file
|
|
compatibility with such assemblers, but does not actually emit anything
|
|
for it.
|
|
|
|
@node If
|
|
@section @code{.if @var{absolute expression}}
|
|
|
|
@cindex conditional assembly
|
|
@cindex @code{if} directive
|
|
@code{.if} marks the beginning of a section of code which is only
|
|
considered part of the source program being assembled if the argument
|
|
(which must be an @var{absolute expression}) is non-zero. The end of
|
|
the conditional section of code must be marked by @code{.endif}
|
|
(@pxref{Endif,,@code{.endif}}); optionally, you may include code for the
|
|
alternative condition, flagged by @code{.else} (@pxref{Else,,@code{.else}}.
|
|
|
|
The following variants of @code{.if} are also supported:
|
|
@table @code
|
|
@item .ifdef @var{symbol}
|
|
@cindex @code{ifdef} directive
|
|
Assembles the following section of code if the specified @var{symbol}
|
|
has been defined.
|
|
|
|
@ignore
|
|
@item .ifeqs
|
|
@cindex @code{ifeqs} directive
|
|
Not yet implemented.
|
|
@end ignore
|
|
|
|
@item .ifndef @var{symbol}
|
|
@itemx ifnotdef @var{symbol}
|
|
@cindex @code{ifndef} directive
|
|
@cindex @code{ifnotdef} directive
|
|
Assembles the following section of code if the specified @var{symbol}
|
|
has not been defined. Both spelling variants are equivalent.
|
|
|
|
@ignore
|
|
@item ifnes
|
|
Not yet implemented.
|
|
@end ignore
|
|
@end table
|
|
|
|
@node Include
|
|
@section @code{.include "@var{file}"}
|
|
|
|
@cindex @code{include} directive
|
|
@cindex supporting files, including
|
|
@cindex files, including
|
|
This directive provides a way to include supporting files at specified
|
|
points in your source program. The code from @var{file} is assembled as
|
|
if it followed the point of the @code{.include}; when the end of the
|
|
included file is reached, assembly of the original file continues. You
|
|
can control the search paths used with the @samp{-I} command-line option
|
|
(@pxref{Invoking,,Command-Line Options}). Quotation marks are required
|
|
around @var{file}.
|
|
|
|
@node Int
|
|
@section @code{.int @var{expressions}}
|
|
|
|
@cindex @code{int} directive
|
|
@ifset GENERIC
|
|
@cindex integers, 32-bit
|
|
Expect zero or more @var{expressions}, of any section, separated by
|
|
commas. For each expression, emit a 32-bit
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifclear H8
|
|
@cindex integers, 32-bit
|
|
Expect zero or more @var{expressions}, of any section, separated by
|
|
commas. For each expression, emit a 32-bit
|
|
@end ifclear
|
|
@ifset H8
|
|
@cindex integers
|
|
Expect zero or more @var{expressions}, of any section, separated by
|
|
commas. For each expression, emit a
|
|
@end ifset
|
|
@end ifclear
|
|
number that will, at run time, be the value of that expression. The
|
|
byte order of the expression depends on what kind of computer will run
|
|
the program.
|
|
|
|
@ifclear GENERIC
|
|
@ifset H8
|
|
On the H8/300 and H8/500, @code{.int} emits 16-bit integers.
|
|
@c start Hitachi-SH
|
|
On the Hitachi SH, however, @code{.int} emits 32-bit integers.
|
|
@c end Hitachi-SH
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@node Lcomm
|
|
@section @code{.lcomm @var{symbol} , @var{length}}
|
|
|
|
@cindex @code{lcomm} directive
|
|
@cindex local common symbols
|
|
@cindex symbols, local common
|
|
Reserve @var{length} (an absolute expression) bytes for a local common
|
|
denoted by @var{symbol}. The section and value of @var{symbol} are
|
|
those of the new local common. The addresses are allocated in the bss
|
|
section, so at run-time the bytes will start off zeroed. @var{Symbol}
|
|
is not declared global (@pxref{Global,,@code{.global}}), so is normally
|
|
not visible to @code{@value{LD}}.
|
|
|
|
@node Lflags
|
|
@section @code{.lflags}
|
|
|
|
@cindex @code{lflags} directive (ignored)
|
|
@code{@value{AS}} accepts this directive, for compatibility with other
|
|
assemblers, but ignores it.
|
|
|
|
@ifclear no-line-dir
|
|
@node Line
|
|
@section @code{.line @var{line-number}}
|
|
|
|
@cindex @code{line} directive
|
|
@end ifclear
|
|
@ifset no-line-dir
|
|
@node Ln
|
|
@section @code{.ln @var{line-number}}
|
|
|
|
@cindex @code{ln} directive
|
|
@end ifset
|
|
@cindex logical line number
|
|
@ifset aout-bout
|
|
Tell @code{@value{AS}} to change the logical line number. @var{line-number} must be
|
|
an absolute expression. The next line will have that logical line
|
|
number. So any other statements on the current line (after a statement
|
|
separator character)
|
|
will be reported as on logical line number
|
|
@var{line-number} @minus{} 1.
|
|
One day this directive will be unsupported: it is used only
|
|
for compatibility with existing assembler programs.
|
|
|
|
@ifset GENERIC
|
|
@ifset A29K
|
|
@emph{Warning:} In the AMD29K configuration of @value{AS}, this command is
|
|
only available with the name @code{.ln}, rather than as either
|
|
@code{.line} or @code{.ln}.
|
|
@end ifset
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@ifclear no-line-dir
|
|
Even though this is a directive associated with the @code{a.out} or
|
|
@code{b.out} object-code formats, @code{@value{AS}} will still recognize it
|
|
when producing COFF output, and will treat @samp{.line} as though it
|
|
were the COFF @samp{.ln} @emph{if} it is found outside a
|
|
@code{.def}/@code{.endef} pair.
|
|
|
|
Inside a @code{.def}, @samp{.line} is, instead, one of the directives
|
|
used by compilers to generate auxiliary symbol information for
|
|
debugging.
|
|
@end ifclear
|
|
|
|
@node Ln
|
|
@section @code{.ln @var{line-number}}
|
|
|
|
@cindex @code{ln} directive
|
|
@ifclear no-line-dir
|
|
@samp{.ln} is a synonym for @samp{.line}.
|
|
@end ifclear
|
|
@ifset no-line-dir
|
|
Tell @code{@value{AS}} to change the logical line number. @var{line-number}
|
|
must be an absolute expression. The next line will have that logical
|
|
line number, so any other statements on the current line (after a
|
|
statement separator character @code{;}) will be reported as on logical
|
|
line number @var{line-number} @minus{} 1.
|
|
@ifset BOUT
|
|
|
|
This directive is accepted, but ignored, when @code{@value{AS}} is
|
|
configured for @code{b.out}; its effect is only associated with COFF
|
|
output format.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@node List
|
|
@section @code{.list}
|
|
|
|
@cindex @code{list} directive
|
|
@cindex listing control, turning on
|
|
Control (in conjunction with the @code{.nolist} directive) whether or
|
|
not assembly listings are generated. These two directives maintain an
|
|
internal counter (which is zero initially). @code{.list} increments the
|
|
counter, and @code{.nolist} decrements it. Assembly listings are
|
|
generated whenever the counter is greater than zero.
|
|
|
|
By default, listings are disabled. When you enable them (with the
|
|
@samp{-a} command line option; @pxref{Invoking,,Command-Line Options}),
|
|
the initial value of the listing counter is one.
|
|
|
|
@node Long
|
|
@section @code{.long @var{expressions}}
|
|
|
|
@cindex @code{long} directive
|
|
@code{.long} is the same as @samp{.int}, @pxref{Int,,@code{.int}}.
|
|
|
|
@ignore
|
|
@c no one seems to know what this is for or whether this description is
|
|
@c what it really ought to do
|
|
@node Lsym
|
|
@section @code{.lsym @var{symbol}, @var{expression}}
|
|
|
|
@cindex @code{lsym} directive
|
|
@cindex symbol, not referenced in assembly
|
|
@code{.lsym} creates a new symbol named @var{symbol}, but does not put it in
|
|
the hash table, ensuring it cannot be referenced by name during the
|
|
rest of the assembly. This sets the attributes of the symbol to be
|
|
the same as the expression value:
|
|
@smallexample
|
|
@var{other} = @var{descriptor} = 0
|
|
@var{type} = @r{(section of @var{expression})}
|
|
@var{value} = @var{expression}
|
|
@end smallexample
|
|
@noindent
|
|
The new symbol is not flagged as external.
|
|
@end ignore
|
|
|
|
@node Nolist
|
|
@section @code{.nolist}
|
|
|
|
@cindex @code{nolist} directive
|
|
@cindex listing control, turning off
|
|
Control (in conjunction with the @code{.list} directive) whether or
|
|
not assembly listings are generated. These two directives maintain an
|
|
internal counter (which is zero initially). @code{.list} increments the
|
|
counter, and @code{.nolist} decrements it. Assembly listings are
|
|
generated whenever the counter is greater than zero.
|
|
|
|
@node Octa
|
|
@section @code{.octa @var{bignums}}
|
|
|
|
@c FIXME: double size emitted for "octa" on i960, others? Or warn?
|
|
@cindex @code{octa} directive
|
|
@cindex integer, 16-byte
|
|
@cindex sixteen byte integer
|
|
This directive expects zero or more bignums, separated by commas. For each
|
|
bignum, it emits a 16-byte integer.
|
|
|
|
The term ``octa'' comes from contexts in which a ``word'' is two bytes;
|
|
hence @emph{octa}-word for 16 bytes.
|
|
|
|
@node Org
|
|
@section @code{.org @var{new-lc} , @var{fill}}
|
|
|
|
@cindex @code{org} directive
|
|
@cindex location counter, advancing
|
|
@cindex advancing location counter
|
|
@cindex current address, advancing
|
|
@code{.org} will advance the location counter of the current section to
|
|
@var{new-lc}. @var{new-lc} is either an absolute expression or an
|
|
expression with the same section as the current subsection. That is,
|
|
you can't use @code{.org} to cross sections: if @var{new-lc} has the
|
|
wrong section, the @code{.org} directive is ignored. To be compatible
|
|
with former assemblers, if the section of @var{new-lc} is absolute,
|
|
@code{@value{AS}} will issue a warning, then pretend the section of @var{new-lc}
|
|
is the same as the current subsection.
|
|
|
|
@code{.org} may only increase the location counter, or leave it
|
|
unchanged; you cannot use @code{.org} to move the location counter
|
|
backwards.
|
|
|
|
@c double negative used below "not undefined" because this is a specific
|
|
@c reference to "undefined" (as SEG_UNKNOWN is called in this manual)
|
|
@c section. pesch@cygnus.com 18feb91
|
|
Because @code{@value{AS}} tries to assemble programs in one pass @var{new-lc}
|
|
may not be undefined. If you really detest this restriction we eagerly await
|
|
a chance to share your improved assembler.
|
|
|
|
Beware that the origin is relative to the start of the section, not
|
|
to the start of the subsection. This is compatible with other
|
|
people's assemblers.
|
|
|
|
When the location counter (of the current subsection) is advanced, the
|
|
intervening bytes are filled with @var{fill} which should be an
|
|
absolute expression. If the comma and @var{fill} are omitted,
|
|
@var{fill} defaults to zero.
|
|
|
|
@node Psize
|
|
@section @code{.psize @var{lines} , @var{columns}}
|
|
|
|
@cindex @code{psize} directive
|
|
@cindex listing control: paper size
|
|
@cindex paper size, for listings
|
|
Use this directive to declare the number of lines---and, optionally, the
|
|
number of columns---to use for each page, when generating listings.
|
|
|
|
If you don't use @code{.psize}, listings will use a default line-count
|
|
of 60. You may omit the comma and @var{columns} specification; the
|
|
default width is 200 columns.
|
|
|
|
@code{@value{AS}} will generate formfeeds whenever the specified number of
|
|
lines is exceeded (or whenever you explicitly request one, using
|
|
@code{.eject}).
|
|
|
|
If you specify @var{lines} as @code{0}, no formfeeds are generated save
|
|
those explicitly specified with @code{.eject}.
|
|
|
|
@node Quad
|
|
@section @code{.quad @var{bignums}}
|
|
|
|
@cindex @code{quad} directive
|
|
@code{.quad} expects zero or more bignums, separated by commas. For
|
|
each bignum, it emits
|
|
@ifclear bignum-16
|
|
an 8-byte integer. If the bignum won't fit in 8 bytes, it prints a
|
|
warning message; and just takes the lowest order 8 bytes of the bignum.
|
|
@cindex eight-byte integer
|
|
@cindex integer, 8-byte
|
|
|
|
The term ``quad'' comes from contexts in which a ``word'' is two bytes;
|
|
hence @emph{quad}-word for 8 bytes.
|
|
@end ifclear
|
|
@ifset bignum-16
|
|
a 16-byte integer. If the bignum won't fit in 16 bytes, it prints a
|
|
warning message; and just takes the lowest order 16 bytes of the bignum.
|
|
@cindex sixteen-byte integer
|
|
@cindex integer, 16-byte
|
|
@end ifset
|
|
|
|
@node Sbttl
|
|
@section @code{.sbttl "@var{subheading}"}
|
|
|
|
@cindex @code{sbttl} directive
|
|
@cindex subtitles for listings
|
|
@cindex listing control: subtitle
|
|
Use @var{subheading} as the title (third line, immediately after the
|
|
title line) when generating assembly listings.
|
|
|
|
This directive affects subsequent pages, as well as the current page if
|
|
it appears within ten lines of the top of a page.
|
|
|
|
@ifset COFF
|
|
@node Scl
|
|
@section @code{.scl @var{class}}
|
|
|
|
@cindex @code{scl} directive
|
|
@cindex symbol storage class (COFF)
|
|
@cindex COFF symbol storage class
|
|
Set the storage-class value for a symbol. This directive may only be
|
|
used inside a @code{.def}/@code{.endef} pair. Storage class may flag
|
|
whether a symbol is static or external, or it may record further
|
|
symbolic debugging information.
|
|
@ifset BOUT
|
|
|
|
The @samp{.scl} directive is primarily associated with COFF output; when
|
|
configured to generate @code{b.out} output format, @code{@value{AS}} will
|
|
accept this directive but ignore it.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@ifset COFF
|
|
@node Section
|
|
@section @code{.section @var{name}, @var{subsection}}
|
|
|
|
@cindex @code{section} directive
|
|
@cindex named section (COFF)
|
|
@cindex COFF named section
|
|
Assemble the following code into end of subsection numbered
|
|
@var{subsection} in the COFF named section @var{name}. If you omit
|
|
@var{subsection}, @code{@value{AS}} uses subsection number zero.
|
|
@samp{.section .text} is equivalent to the @code{.text} directive;
|
|
@samp{.section .data} is equivalent to the @code{.data} directive.
|
|
@end ifset
|
|
|
|
@node Set
|
|
@section @code{.set @var{symbol}, @var{expression}}
|
|
|
|
@cindex @code{set} directive
|
|
@cindex symbol value, setting
|
|
This directive sets the value of @var{symbol} to @var{expression}. This
|
|
will change @var{symbol}'s value and type to conform to
|
|
@var{expression}. If @var{symbol} was flagged as external, it remains
|
|
flagged. (@xref{Symbol Attributes}.)
|
|
|
|
You may @code{.set} a symbol many times in the same assembly.
|
|
If the expression's section is unknowable during pass 1, a second
|
|
pass over the source program will be forced. The second pass is
|
|
currently not implemented. @code{@value{AS}} will abort with an error
|
|
message if one is required.
|
|
|
|
If you @code{.set} a global symbol, the value stored in the object
|
|
file is the last value stored into it.
|
|
|
|
@node Short
|
|
@section @code{.short @var{expressions}}
|
|
|
|
@cindex @code{short} directive
|
|
@ifset GENERIC
|
|
@code{.short} is normally the same as @samp{.word}.
|
|
@xref{Word,,@code{.word}}.
|
|
|
|
In some configurations, however, @code{.short} and @code{.word} generate
|
|
numbers of different lengths; @pxref{Machine Dependencies}.
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset W16
|
|
@code{.short} is the same as @samp{.word}. @xref{Word,,@code{.word}}.
|
|
@end ifset
|
|
@ifset W32
|
|
This expects zero or more @var{expressions}, and emits
|
|
a 16 bit number for each.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@node Single
|
|
@section @code{.single @var{flonums}}
|
|
|
|
@cindex @code{single} directive
|
|
@cindex floating point numbers (single)
|
|
This directive assembles zero or more flonums, separated by commas. It
|
|
has the same effect as @code{.float}.
|
|
@ifset GENERIC
|
|
The exact kind of floating point numbers emitted depends on how
|
|
@code{@value{AS}} is configured. @xref{Machine Dependencies}.
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@ifset IEEEFLOAT
|
|
On the @value{TARGET} family, @code{.single} emits 32-bit floating point
|
|
numbers in @sc{ieee} format.
|
|
@end ifset
|
|
@end ifclear
|
|
|
|
@ifset COFF
|
|
@node Size
|
|
@section @code{.size}
|
|
|
|
@cindex @code{size} directive
|
|
This directive is generated by compilers to include auxiliary debugging
|
|
information in the symbol table. It is only permitted inside
|
|
@code{.def}/@code{.endef} pairs.
|
|
@ifset BOUT
|
|
|
|
@samp{.size} is only meaningful when generating COFF format output; when
|
|
@code{@value{AS}} is generating @code{b.out}, it accepts this directive but
|
|
ignores it.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@ifclear no-space-dir
|
|
@node Space
|
|
@section @code{.space @var{size} , @var{fill}}
|
|
|
|
@cindex @code{space} directive
|
|
@cindex filling memory
|
|
This directive emits @var{size} bytes, each of value @var{fill}. Both
|
|
@var{size} and @var{fill} are absolute expressions. If the comma
|
|
and @var{fill} are omitted, @var{fill} is assumed to be zero.
|
|
@end ifclear
|
|
|
|
@ifset A29K
|
|
@ifclear GENERIC
|
|
@node Space
|
|
@section @code{.space}
|
|
@cindex @code{space} directive
|
|
@end ifclear
|
|
On the AMD 29K, this directive is ignored; it is accepted for
|
|
compatibility with other AMD 29K assemblers.
|
|
|
|
@quotation
|
|
@emph{Warning:} In most versions of the GNU assembler, the directive
|
|
@code{.space} has the effect of @code{.block} @xref{Machine Dependencies}.
|
|
@end quotation
|
|
@end ifset
|
|
|
|
@ifset have-stabs
|
|
@node Stab
|
|
@section @code{.stabd, .stabn, .stabs}
|
|
|
|
@cindex symbolic debuggers, information for
|
|
@cindex @code{stab@var{x}} directives
|
|
There are three directives that begin @samp{.stab}.
|
|
All emit symbols (@pxref{Symbols}), for use by symbolic debuggers.
|
|
The symbols are not entered in the @code{@value{AS}} hash table: they
|
|
cannot be referenced elsewhere in the source file.
|
|
Up to five fields are required:
|
|
|
|
@table @var
|
|
@item string
|
|
This is the symbol's name. It may contain any character except
|
|
@samp{\000}, so is more general than ordinary symbol names. Some
|
|
debuggers used to code arbitrarily complex structures into symbol names
|
|
using this field.
|
|
|
|
@item type
|
|
An absolute expression. The symbol's type is set to the low 8 bits of
|
|
this expression. Any bit pattern is permitted, but @code{@value{LD}}
|
|
and debuggers will choke on silly bit patterns.
|
|
|
|
@item other
|
|
An absolute expression. The symbol's ``other'' attribute is set to the
|
|
low 8 bits of this expression.
|
|
|
|
@item desc
|
|
An absolute expression. The symbol's descriptor is set to the low 16
|
|
bits of this expression.
|
|
|
|
@item value
|
|
An absolute expression which becomes the symbol's value.
|
|
@end table
|
|
|
|
If a warning is detected while reading a @code{.stabd}, @code{.stabn},
|
|
or @code{.stabs} statement, the symbol has probably already been created
|
|
and you will get a half-formed symbol in your object file. This is
|
|
compatible with earlier assemblers!
|
|
|
|
@table @code
|
|
@cindex @code{stabd} directive
|
|
@item .stabd @var{type} , @var{other} , @var{desc}
|
|
|
|
The ``name'' of the symbol generated is not even an empty string.
|
|
It is a null pointer, for compatibility. Older assemblers used a
|
|
null pointer so they didn't waste space in object files with empty
|
|
strings.
|
|
|
|
The symbol's value is set to the location counter,
|
|
relocatably. When your program is linked, the value of this symbol
|
|
will be where the location counter was when the @code{.stabd} was
|
|
assembled.
|
|
|
|
@item .stabn @var{type} , @var{other} , @var{desc} , @var{value}
|
|
@cindex @code{stabn} directive
|
|
The name of the symbol is set to the empty string @code{""}.
|
|
|
|
@item .stabs @var{string} , @var{type} , @var{other} , @var{desc} , @var{value}
|
|
@cindex @code{stabs} directive
|
|
All five fields are specified.
|
|
@end table
|
|
@end ifset
|
|
@c end have-stabs
|
|
|
|
@ifset COFF
|
|
@node Tag
|
|
@section @code{.tag @var{structname}}
|
|
|
|
@cindex COFF structure debugging
|
|
@cindex structure debugging, COFF
|
|
@cindex @code{tag} directive
|
|
This directive is generated by compilers to include auxiliary debugging
|
|
information in the symbol table. It is only permitted inside
|
|
@code{.def}/@code{.endef} pairs. Tags are used to link structure
|
|
definitions in the symbol table with instances of those structures.
|
|
@ifset BOUT
|
|
|
|
@samp{.tag} is only used when generating COFF format output; when
|
|
@code{@value{AS}} is generating @code{b.out}, it accepts this directive but
|
|
ignores it.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@node Text
|
|
@section @code{.text @var{subsection}}
|
|
|
|
@cindex @code{text} directive
|
|
Tells @code{@value{AS}} to assemble the following statements onto the end of
|
|
the text subsection numbered @var{subsection}, which is an absolute
|
|
expression. If @var{subsection} is omitted, subsection number zero
|
|
is used.
|
|
|
|
@node Title
|
|
@section @code{.title "@var{heading}"}
|
|
|
|
@cindex @code{title} directive
|
|
@cindex listing control: title line
|
|
Use @var{heading} as the title (second line, immediately after the
|
|
source file name and pagenumber) when generating assembly listings.
|
|
|
|
This directive affects subsequent pages, as well as the current page if
|
|
it appears within ten lines of the top of a page.
|
|
|
|
@ifset COFF
|
|
@node Type
|
|
@section @code{.type @var{int}}
|
|
|
|
@cindex COFF symbol type
|
|
@cindex symbol type, COFF
|
|
@cindex @code{type} directive
|
|
This directive, permitted only within @code{.def}/@code{.endef} pairs,
|
|
records the integer @var{int} as the type attribute of a symbol table entry.
|
|
@ifset BOUT
|
|
|
|
@samp{.type} is associated only with COFF format output; when
|
|
@code{@value{AS}} is configured for @code{b.out} output, it accepts this
|
|
directive but ignores it.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@ifset COFF
|
|
@node Val
|
|
@section @code{.val @var{addr}}
|
|
|
|
@cindex @code{val} directive
|
|
@cindex COFF value attribute
|
|
@cindex value attribute, COFF
|
|
This directive, permitted only within @code{.def}/@code{.endef} pairs,
|
|
records the address @var{addr} as the value attribute of a symbol table
|
|
entry.
|
|
@ifset BOUT
|
|
|
|
@samp{.val} is used only for COFF output; when @code{@value{AS}} is
|
|
configured for @code{b.out}, it accepts this directive but ignores it.
|
|
@end ifset
|
|
@end ifset
|
|
|
|
@node Word
|
|
@section @code{.word @var{expressions}}
|
|
|
|
@cindex @code{word} directive
|
|
This directive expects zero or more @var{expressions}, of any section,
|
|
separated by commas.
|
|
@ifclear GENERIC
|
|
@ifset W32
|
|
For each expression, @code{@value{AS}} emits a 32-bit number.
|
|
@end ifset
|
|
@ifset W16
|
|
For each expression, @code{@value{AS}} emits a 16-bit number.
|
|
@end ifset
|
|
@end ifclear
|
|
@ifset GENERIC
|
|
|
|
The size of the number emitted, and its byte order,
|
|
depends on what kind of computer will run the program.
|
|
@end ifset
|
|
|
|
@c on amd29k, i960, sparc the "special treatment to support compilers" doesn't
|
|
@c happen---32-bit addressability, period; no long/short jumps.
|
|
@ifset DIFF-TBL-KLUGE
|
|
@cindex difference tables altered
|
|
@cindex altered difference tables
|
|
@quotation
|
|
@emph{Warning: Special Treatment to support Compilers}
|
|
@end quotation
|
|
|
|
@ifset GENERIC
|
|
Machines with a 32-bit address space, but that do less than 32-bit
|
|
addressing, require the following special treatment. If the machine of
|
|
interest to you does 32-bit addressing (or doesn't require it;
|
|
@pxref{Machine Dependencies}), you can ignore this issue.
|
|
|
|
@end ifset
|
|
In order to assemble compiler output into something that will work,
|
|
@code{@value{AS}} will occasionlly do strange things to @samp{.word} directives.
|
|
Directives of the form @samp{.word sym1-sym2} are often emitted by
|
|
compilers as part of jump tables. Therefore, when @code{@value{AS}} assembles a
|
|
directive of the form @samp{.word sym1-sym2}, and the difference between
|
|
@code{sym1} and @code{sym2} does not fit in 16 bits, @code{@value{AS}} will
|
|
create a @dfn{secondary jump table}, immediately before the next label.
|
|
This secondary jump table will be preceded by a short-jump to the
|
|
first byte after the secondary table. This short-jump prevents the flow
|
|
of control from accidentally falling into the new table. Inside the
|
|
table will be a long-jump to @code{sym2}. The original @samp{.word}
|
|
will contain @code{sym1} minus the address of the long-jump to
|
|
@code{sym2}.
|
|
|
|
If there were several occurrences of @samp{.word sym1-sym2} before the
|
|
secondary jump table, all of them will be adjusted. If there was a
|
|
@samp{.word sym3-sym4}, that also did not fit in sixteen bits, a
|
|
long-jump to @code{sym4} will be included in the secondary jump table,
|
|
and the @code{.word} directives will be adjusted to contain @code{sym3}
|
|
minus the address of the long-jump to @code{sym4}; and so on, for as many
|
|
entries in the original jump table as necessary.
|
|
|
|
@ifset INTERNALS
|
|
@emph{This feature may be disabled by compiling @code{@value{AS}} with the
|
|
@samp{-DWORKING_DOT_WORD} option.} This feature is likely to confuse
|
|
assembly language programmers.
|
|
@end ifset
|
|
@end ifset
|
|
@c end DIFF-TBL-KLUGE
|
|
|
|
@node Deprecated
|
|
@section Deprecated Directives
|
|
|
|
@cindex deprecated directives
|
|
@cindex obsolescent directives
|
|
One day these directives won't work.
|
|
They are included for compatibility with older assemblers.
|
|
@table @t
|
|
@item .abort
|
|
@item .app-file
|
|
@item .line
|
|
@end table
|
|
|
|
@ifset GENERIC
|
|
@node Machine Dependencies
|
|
@chapter Machine Dependent Features
|
|
|
|
@cindex machine dependencies
|
|
The machine instruction sets are (almost by definition) different on
|
|
each machine where @code{@value{AS}} runs. Floating point representations
|
|
vary as well, and @code{@value{AS}} often supports a few additional
|
|
directives or command-line options for compatibility with other
|
|
assemblers on a particular platform. Finally, some versions of
|
|
@code{@value{AS}} support special pseudo-instructions for branch
|
|
optimization.
|
|
|
|
This chapter discusses most of these differences, though it does not
|
|
include details on any machine's instruction set. For details on that
|
|
subject, see the hardware manufacturer's manual.
|
|
|
|
@menu
|
|
@ifset VAX
|
|
* Vax-Dependent:: VAX Dependent Features
|
|
@end ifset
|
|
@ifset A29K
|
|
* AMD29K-Dependent:: AMD 29K Dependent Features
|
|
@end ifset
|
|
@ifset H8/300
|
|
* H8/300-Dependent:: Hitachi H8/300 Dependent Features
|
|
@end ifset
|
|
@ifset H8/500
|
|
* H8/500-Dependent:: Hitachi H8/500 Dependent Features
|
|
@end ifset
|
|
@c start Hitachi-SH
|
|
@ifset SH
|
|
* SH-Dependent:: Hitachi SH Dependent Features
|
|
@end ifset
|
|
@c end Hitachi-SH
|
|
@ifset I960
|
|
* i960-Dependent:: Intel 80960 Dependent Features
|
|
@end ifset
|
|
@ifset M680X0
|
|
* M68K-Dependent:: M680x0 Dependent Features
|
|
@end ifset
|
|
@ifset SPARC
|
|
* Sparc-Dependent:: SPARC Dependent Features
|
|
@end ifset
|
|
@ifset Z8000
|
|
* Z8000-Dependent:: Z8000 Dependent Features
|
|
@end ifset
|
|
@ifset I80386
|
|
* i386-Dependent:: 80386 Dependent Features
|
|
@end ifset
|
|
@end menu
|
|
|
|
@down
|
|
@end ifset
|
|
|
|
@c The following major nodes are *sections* in the GENERIC version, *chapters*
|
|
@c in single-cpu versions. This is mainly achieved by @down. There is a
|
|
@c peculiarity: to preserve cross-references, there must be a node called
|
|
@c "Machine Dependencies". Hence the conditional nodenames in each
|
|
@c major node below. Node defaulting in makeinfo requires adjacency of
|
|
@c node and sectioning commands; hence the repetition of @chapter BLAH
|
|
@c in both conditional blocks.
|
|
@c
|
|
@ifset VAX
|
|
@ifset GENERIC
|
|
@node Vax-Dependent
|
|
@chapter VAX Dependent Features
|
|
@cindex VAX support
|
|
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@node Machine Dependencies
|
|
@chapter VAX Dependent Features
|
|
@cindex VAX support
|
|
|
|
@end ifclear
|
|
|
|
@menu
|
|
* Vax-Opts:: VAX Command-Line Options
|
|
* VAX-float:: VAX Floating Point
|
|
* VAX-directives:: Vax Machine Directives
|
|
* VAX-opcodes:: VAX Opcodes
|
|
* VAX-branch:: VAX Branch Improvement
|
|
* VAX-operands:: VAX Operands
|
|
* VAX-no:: Not Supported on VAX
|
|
@end menu
|
|
|
|
|
|
@node Vax-Opts
|
|
@section VAX Command-Line Options
|
|
|
|
@cindex command-line options ignored, VAX
|
|
@cindex VAX command-line options ignored
|
|
The Vax version of @code{@value{AS}} accepts any of the following options,
|
|
gives a warning message that the option was ignored and proceeds.
|
|
These options are for compatibility with scripts designed for other
|
|
people's assemblers.
|
|
|
|
@table @asis
|
|
@item @kbd{-D} (Debug)
|
|
@itemx @kbd{-S} (Symbol Table)
|
|
@itemx @kbd{-T} (Token Trace)
|
|
@cindex @code{-D}, ignored on VAX
|
|
@cindex @code{-S}, ignored on VAX
|
|
@cindex @code{-T}, ignored on VAX
|
|
These are obsolete options used to debug old assemblers.
|
|
|
|
@item @kbd{-d} (Displacement size for JUMPs)
|
|
@cindex @code{-d}, VAX option
|
|
This option expects a number following the @kbd{-d}. Like options
|
|
that expect filenames, the number may immediately follow the
|
|
@kbd{-d} (old standard) or constitute the whole of the command line
|
|
argument that follows @kbd{-d} (GNU standard).
|
|
|
|
@item @kbd{-V} (Virtualize Interpass Temporary File)
|
|
@cindex @code{-V}, redundant on VAX
|
|
Some other assemblers use a temporary file. This option
|
|
commanded them to keep the information in active memory rather
|
|
than in a disk file. @code{@value{AS}} always does this, so this
|
|
option is redundant.
|
|
|
|
@item @kbd{-J} (JUMPify Longer Branches)
|
|
@cindex @code{-J}, ignored on VAX
|
|
Many 32-bit computers permit a variety of branch instructions
|
|
to do the same job. Some of these instructions are short (and
|
|
fast) but have a limited range; others are long (and slow) but
|
|
can branch anywhere in virtual memory. Often there are 3
|
|
flavors of branch: short, medium and long. Some other
|
|
assemblers would emit short and medium branches, unless told by
|
|
this option to emit short and long branches.
|
|
|
|
@item @kbd{-t} (Temporary File Directory)
|
|
@cindex @code{-t}, ignored on VAX
|
|
Some other assemblers may use a temporary file, and this option
|
|
takes a filename being the directory to site the temporary
|
|
file. Since @code{@value{AS}} does not use a temporary disk file, this
|
|
option makes no difference. @kbd{-t} needs exactly one
|
|
filename.
|
|
@end table
|
|
|
|
@cindex VMS (VAX) options
|
|
@cindex options for VAX/VMS
|
|
@cindex VAX/VMS options
|
|
@cindex @code{-h} option, VAX/VMS
|
|
@cindex @code{-+} option, VAX/VMS
|
|
@cindex Vax-11 C compatibility
|
|
@cindex symbols with lowercase, VAX/VMS
|
|
@c FIXME! look into "I think" below, correct if needed, delete.
|
|
The Vax version of the assembler accepts two options when
|
|
compiled for VMS. They are @kbd{-h}, and @kbd{-+}. The
|
|
@kbd{-h} option prevents @code{@value{AS}} from modifying the
|
|
symbol-table entries for symbols that contain lowercase
|
|
characters (I think). The @kbd{-+} option causes @code{@value{AS}} to
|
|
print warning messages if the FILENAME part of the object file,
|
|
or any symbol name is larger than 31 characters. The @kbd{-+}
|
|
option also insertes some code following the @samp{_main}
|
|
symbol so that the object file will be compatible with Vax-11
|
|
"C".
|
|
|
|
@node VAX-float
|
|
@section VAX Floating Point
|
|
|
|
@cindex VAX floating point
|
|
@cindex floating point, VAX
|
|
Conversion of flonums to floating point is correct, and
|
|
compatible with previous assemblers. Rounding is
|
|
towards zero if the remainder is exactly half the least significant bit.
|
|
|
|
@code{D}, @code{F}, @code{G} and @code{H} floating point formats
|
|
are understood.
|
|
|
|
Immediate floating literals (@emph{e.g.} @samp{S`$6.9})
|
|
are rendered correctly. Again, rounding is towards zero in the
|
|
boundary case.
|
|
|
|
@cindex @code{float} directive, VAX
|
|
@cindex @code{double} directive, VAX
|
|
The @code{.float} directive produces @code{f} format numbers.
|
|
The @code{.double} directive produces @code{d} format numbers.
|
|
|
|
@node VAX-directives
|
|
@section Vax Machine Directives
|
|
|
|
@cindex machine directives, VAX
|
|
@cindex VAX machine directives
|
|
The Vax version of the assembler supports four directives for
|
|
generating Vax floating point constants. They are described in the
|
|
table below.
|
|
|
|
@cindex wide floating point directives, VAX
|
|
@table @code
|
|
@item .dfloat
|
|
@cindex @code{dfloat} directive, VAX
|
|
This expects zero or more flonums, separated by commas, and
|
|
assembles Vax @code{d} format 64-bit floating point constants.
|
|
|
|
@item .ffloat
|
|
@cindex @code{ffloat} directive, VAX
|
|
This expects zero or more flonums, separated by commas, and
|
|
assembles Vax @code{f} format 32-bit floating point constants.
|
|
|
|
@item .gfloat
|
|
@cindex @code{gfloat} directive, VAX
|
|
This expects zero or more flonums, separated by commas, and
|
|
assembles Vax @code{g} format 64-bit floating point constants.
|
|
|
|
@item .hfloat
|
|
@cindex @code{hfloat} directive, VAX
|
|
This expects zero or more flonums, separated by commas, and
|
|
assembles Vax @code{h} format 128-bit floating point constants.
|
|
|
|
@end table
|
|
|
|
@node VAX-opcodes
|
|
@section VAX Opcodes
|
|
|
|
@cindex VAX opcode mnemonics
|
|
@cindex opcode mnemonics, VAX
|
|
@cindex mnemonics for opcodes, VAX
|
|
All DEC mnemonics are supported. Beware that @code{case@dots{}}
|
|
instructions have exactly 3 operands. The dispatch table that
|
|
follows the @code{case@dots{}} instruction should be made with
|
|
@code{.word} statements. This is compatible with all unix
|
|
assemblers we know of.
|
|
|
|
@node VAX-branch
|
|
@section VAX Branch Improvement
|
|
|
|
@cindex VAX branch improvement
|
|
@cindex branch improvement, VAX
|
|
@cindex pseudo-ops for branch, VAX
|
|
Certain pseudo opcodes are permitted. They are for branch
|
|
instructions. They expand to the shortest branch instruction that
|
|
will reach the target. Generally these mnemonics are made by
|
|
substituting @samp{j} for @samp{b} at the start of a DEC mnemonic.
|
|
This feature is included both for compatibility and to help
|
|
compilers. If you don't need this feature, don't use these
|
|
opcodes. Here are the mnemonics, and the code they can expand into.
|
|
|
|
@table @code
|
|
@item jbsb
|
|
@samp{Jsb} is already an instruction mnemonic, so we chose @samp{jbsb}.
|
|
@table @asis
|
|
@item (byte displacement)
|
|
@kbd{bsbb @dots{}}
|
|
@item (word displacement)
|
|
@kbd{bsbw @dots{}}
|
|
@item (long displacement)
|
|
@kbd{jsb @dots{}}
|
|
@end table
|
|
@item jbr
|
|
@itemx jr
|
|
Unconditional branch.
|
|
@table @asis
|
|
@item (byte displacement)
|
|
@kbd{brb @dots{}}
|
|
@item (word displacement)
|
|
@kbd{brw @dots{}}
|
|
@item (long displacement)
|
|
@kbd{jmp @dots{}}
|
|
@end table
|
|
@item j@var{COND}
|
|
@var{COND} may be any one of the conditional branches
|
|
@code{neq}, @code{nequ}, @code{eql}, @code{eqlu}, @code{gtr},
|
|
@code{geq}, @code{lss}, @code{gtru}, @code{lequ}, @code{vc}, @code{vs},
|
|
@code{gequ}, @code{cc}, @code{lssu}, @code{cs}.
|
|
@var{COND} may also be one of the bit tests
|
|
@code{bs}, @code{bc}, @code{bss}, @code{bcs}, @code{bsc}, @code{bcc},
|
|
@code{bssi}, @code{bcci}, @code{lbs}, @code{lbc}.
|
|
@var{NOTCOND} is the opposite condition to @var{COND}.
|
|
@table @asis
|
|
@item (byte displacement)
|
|
@kbd{b@var{COND} @dots{}}
|
|
@item (word displacement)
|
|
@kbd{b@var{NOTCOND} foo ; brw @dots{} ; foo:}
|
|
@item (long displacement)
|
|
@kbd{b@var{NOTCOND} foo ; jmp @dots{} ; foo:}
|
|
@end table
|
|
@item jacb@var{X}
|
|
@var{X} may be one of @code{b d f g h l w}.
|
|
@table @asis
|
|
@item (word displacement)
|
|
@kbd{@var{OPCODE} @dots{}}
|
|
@item (long displacement)
|
|
@example
|
|
@var{OPCODE} @dots{}, foo ;
|
|
brb bar ;
|
|
foo: jmp @dots{} ;
|
|
bar:
|
|
@end example
|
|
@end table
|
|
@item jaob@var{YYY}
|
|
@var{YYY} may be one of @code{lss leq}.
|
|
@item jsob@var{ZZZ}
|
|
@var{ZZZ} may be one of @code{geq gtr}.
|
|
@table @asis
|
|
@item (byte displacement)
|
|
@kbd{@var{OPCODE} @dots{}}
|
|
@item (word displacement)
|
|
@example
|
|
@var{OPCODE} @dots{}, foo ;
|
|
brb bar ;
|
|
foo: brw @var{destination} ;
|
|
bar:
|
|
@end example
|
|
@item (long displacement)
|
|
@example
|
|
@var{OPCODE} @dots{}, foo ;
|
|
brb bar ;
|
|
foo: jmp @var{destination} ;
|
|
bar:
|
|
@end example
|
|
@end table
|
|
@item aobleq
|
|
@itemx aoblss
|
|
@itemx sobgeq
|
|
@itemx sobgtr
|
|
@table @asis
|
|
@item (byte displacement)
|
|
@kbd{@var{OPCODE} @dots{}}
|
|
@item (word displacement)
|
|
@example
|
|
@var{OPCODE} @dots{}, foo ;
|
|
brb bar ;
|
|
foo: brw @var{destination} ;
|
|
bar:
|
|
@end example
|
|
@item (long displacement)
|
|
@example
|
|
@var{OPCODE} @dots{}, foo ;
|
|
brb bar ;
|
|
foo: jmp @var{destination} ;
|
|
bar:
|
|
@end example
|
|
@end table
|
|
@end table
|
|
|
|
@node VAX-operands
|
|
@section VAX Operands
|
|
|
|
@cindex VAX operand notation
|
|
@cindex operand notation, VAX
|
|
@cindex immediate character, VAX
|
|
@cindex VAX immediate character
|
|
The immediate character is @samp{$} for Unix compatibility, not
|
|
@samp{#} as DEC writes it.
|
|
|
|
@cindex indirect character, VAX
|
|
@cindex VAX indirect character
|
|
The indirect character is @samp{*} for Unix compatibility, not
|
|
@samp{@@} as DEC writes it.
|
|
|
|
@cindex displacement sizing character, VAX
|
|
@cindex VAX displacement sizing character
|
|
The displacement sizing character is @samp{`} (an accent grave) for
|
|
Unix compatibility, not @samp{^} as DEC writes it. The letter
|
|
preceding @samp{`} may have either case. @samp{G} is not
|
|
understood, but all other letters (@code{b i l s w}) are understood.
|
|
|
|
@cindex register names, VAX
|
|
@cindex VAX register names
|
|
Register names understood are @code{r0 r1 r2 @dots{} r15 ap fp sp
|
|
pc}. Any case of letters will do.
|
|
|
|
For instance
|
|
@smallexample
|
|
tstb *w`$4(r5)
|
|
@end smallexample
|
|
|
|
Any expression is permitted in an operand. Operands are comma
|
|
separated.
|
|
|
|
@c There is some bug to do with recognizing expressions
|
|
@c in operands, but I forget what it is. It is
|
|
@c a syntax clash because () is used as an address mode
|
|
@c and to encapsulate sub-expressions.
|
|
|
|
@node VAX-no
|
|
@section Not Supported on VAX
|
|
|
|
@cindex VAX bitfields not supported
|
|
@cindex bitfields, not supported on VAX
|
|
Vax bit fields can not be assembled with @code{@value{AS}}. Someone
|
|
can add the required code if they really need it.
|
|
|
|
@end ifset
|
|
@ifset A29K
|
|
@ifset GENERIC
|
|
@page
|
|
@node AMD29K-Dependent
|
|
@chapter AMD 29K Dependent Features
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@node Machine Dependencies
|
|
@chapter AMD 29K Dependent Features
|
|
@end ifclear
|
|
|
|
@cindex AMD 29K support
|
|
@cindex 29K support
|
|
@menu
|
|
* AMD29K Options:: Options
|
|
* AMD29K Syntax:: Syntax
|
|
* AMD29K Floating Point:: Floating Point
|
|
* AMD29K Directives:: AMD 29K Machine Directives
|
|
* AMD29K Opcodes:: Opcodes
|
|
@end menu
|
|
|
|
@node AMD29K Options
|
|
@section Options
|
|
@cindex AMD 29K options (none)
|
|
@cindex options for AMD29K (none)
|
|
@code{@value{AS}} has no additional command-line options for the AMD
|
|
29K family.
|
|
|
|
@node AMD29K Syntax
|
|
@section Syntax
|
|
@menu
|
|
* AMD29K-Chars:: Special Characters
|
|
* AMD29K-Regs:: Register Names
|
|
@end menu
|
|
|
|
@node AMD29K-Chars
|
|
@subsection Special Characters
|
|
|
|
@cindex line comment character, AMD 29K
|
|
@cindex AMD 29K line comment character
|
|
@samp{;} is the line comment character.
|
|
|
|
@cindex line separator, AMD 29K
|
|
@cindex AMD 29K line separator
|
|
@cindex statement separator, AMD 29K
|
|
@cindex AMD 29K statement separator
|
|
@samp{@@} can be used instead of a newline to separate statements.
|
|
|
|
@cindex identifiers, AMD 29K
|
|
@cindex AMD 29K identifiers
|
|
The character @samp{?} is permitted in identifiers (but may not begin
|
|
an identifier).
|
|
|
|
@node AMD29K-Regs
|
|
@subsection Register Names
|
|
|
|
@cindex AMD 29K register names
|
|
@cindex register names, AMD 29K
|
|
General-purpose registers are represented by predefined symbols of the
|
|
form @samp{GR@var{nnn}} (for global registers) or @samp{LR@var{nnn}}
|
|
(for local registers), where @var{nnn} represents a number between
|
|
@code{0} and @code{127}, written with no leading zeros. The leading
|
|
letters may be in either upper or lower case; for example, @samp{gr13}
|
|
and @samp{LR7} are both valid register names.
|
|
|
|
You may also refer to general-purpose registers by specifying the
|
|
register number as the result of an expression (prefixed with @samp{%%}
|
|
to flag the expression as a register number):
|
|
@smallexample
|
|
%%@var{expression}
|
|
@end smallexample
|
|
@noindent
|
|
---where @var{expression} must be an absolute expression evaluating to a
|
|
number between @code{0} and @code{255}. The range [0, 127] refers to
|
|
global registers, and the range [128, 255] to local registers.
|
|
|
|
@cindex special purpose registers, AMD 29K
|
|
@cindex AMD 29K special purpose registers
|
|
@cindex protected registers, AMD 29K
|
|
@cindex AMD 29K protected registers
|
|
In addition, @code{@value{AS}} understands the following protected
|
|
special-purpose register names for the AMD 29K family:
|
|
|
|
@smallexample
|
|
vab chd pc0
|
|
ops chc pc1
|
|
cps rbp pc2
|
|
cfg tmc mmu
|
|
cha tmr lru
|
|
@end smallexample
|
|
|
|
These unprotected special-purpose register names are also recognized:
|
|
@smallexample
|
|
ipc alu fpe
|
|
ipa bp inte
|
|
ipb fc fps
|
|
q cr exop
|
|
@end smallexample
|
|
|
|
@node AMD29K Floating Point
|
|
@section Floating Point
|
|
|
|
@cindex floating point, AMD 29K (@sc{ieee})
|
|
@cindex AMD 29K floating point (@sc{ieee})
|
|
The AMD 29K family uses @sc{ieee} floating-point numbers.
|
|
|
|
@node AMD29K Directives
|
|
@section AMD 29K Machine Directives
|
|
|
|
@cindex machine directives, AMD 29K
|
|
@cindex AMD 29K machine directives
|
|
@table @code
|
|
@item .block @var{size} , @var{fill}
|
|
@cindex @code{block} directive, AMD 29K
|
|
This directive emits @var{size} bytes, each of value @var{fill}. Both
|
|
@var{size} and @var{fill} are absolute expressions. If the comma
|
|
and @var{fill} are omitted, @var{fill} is assumed to be zero.
|
|
|
|
In other versions of the GNU assembler, this directive is called
|
|
@samp{.space}.
|
|
@end table
|
|
|
|
@table @code
|
|
@item .cputype
|
|
@cindex @code{cputype} directive, AMD 29K
|
|
This directive is ignored; it is accepted for compatibility with other
|
|
AMD 29K assemblers.
|
|
|
|
@item .file
|
|
@cindex @code{file} directive, AMD 29K
|
|
This directive is ignored; it is accepted for compatibility with other
|
|
AMD 29K assemblers.
|
|
|
|
@quotation
|
|
@emph{Warning:} in other versions of the GNU assembler, @code{.file} is
|
|
used for the directive called @code{.app-file} in the AMD 29K support.
|
|
@end quotation
|
|
|
|
@item .line
|
|
@cindex @code{line} directive, AMD 29K
|
|
This directive is ignored; it is accepted for compatibility with other
|
|
AMD 29K assemblers.
|
|
|
|
@ignore
|
|
@c since we're ignoring .lsym...
|
|
@item .reg @var{symbol}, @var{expression}
|
|
@cindex @code{reg} directive, AMD 29K
|
|
@code{.reg} has the same effect as @code{.lsym}; @pxref{Lsym,,@code{.lsym}}.
|
|
@end ignore
|
|
|
|
@item .sect
|
|
@cindex @code{sect} directive, AMD 29K
|
|
This directive is ignored; it is accepted for compatibility with other
|
|
AMD 29K assemblers.
|
|
|
|
@item .use @var{section name}
|
|
@cindex @code{use} directive, AMD 29K
|
|
Establishes the section and subsection for the following code;
|
|
@var{section name} may be one of @code{.text}, @code{.data},
|
|
@code{.data1}, or @code{.lit}. With one of the first three @var{section
|
|
name} options, @samp{.use} is equivalent to the machine directive
|
|
@var{section name}; the remaining case, @samp{.use .lit}, is the same as
|
|
@samp{.data 200}.
|
|
@end table
|
|
|
|
@node AMD29K Opcodes
|
|
@section Opcodes
|
|
|
|
@cindex AMD 29K opcodes
|
|
@cindex opcodes for AMD 29K
|
|
@code{@value{AS}} implements all the standard AMD 29K opcodes. No
|
|
additional pseudo-instructions are needed on this family.
|
|
|
|
For information on the 29K machine instruction set, see @cite{Am29000
|
|
User's Manual}, Advanced Micro Devices, Inc.
|
|
|
|
@end ifset
|
|
@ifset Hitachi-all
|
|
@ifclear GENERIC
|
|
@node Machine Dependencies
|
|
@chapter Machine Dependent Features
|
|
|
|
The machine instruction sets are different on each Hitachi chip family,
|
|
and there are also some syntax differences among the families. This
|
|
chapter describes the specific @code{@value{AS}} features for each
|
|
family.
|
|
|
|
@menu
|
|
* H8/300-Dependent:: Hitachi H8/300 Dependent Features
|
|
* H8/500-Dependent:: Hitachi H8/500 Dependent Features
|
|
@c start Hitachi-SH
|
|
|
|
* SH-Dependent:: Hitachi SH Dependent Features
|
|
@c end Hitachi-SH
|
|
@end menu
|
|
@down
|
|
@end ifclear
|
|
@end ifset
|
|
|
|
@ifset H8/300
|
|
@ifset GENERIC
|
|
@page
|
|
@end ifset
|
|
@node H8/300-Dependent
|
|
@chapter H8/300 Dependent Features
|
|
|
|
@cindex H8/300 support
|
|
@menu
|
|
* H8/300 Options:: Options
|
|
* H8/300 Syntax:: Syntax
|
|
* H8/300 Floating Point:: Floating Point
|
|
* H8/300 Directives:: H8/300 Machine Directives
|
|
* H8/300 Opcodes:: Opcodes
|
|
@end menu
|
|
|
|
@node H8/300 Options
|
|
@section Options
|
|
|
|
@cindex H8/300 options (none)
|
|
@cindex options, H8/300 (none)
|
|
@code{@value{AS}} has no additional command-line options for the Hitachi
|
|
H8/300 family.
|
|
|
|
@node H8/300 Syntax
|
|
@section Syntax
|
|
@menu
|
|
* H8/300-Chars:: Special Characters
|
|
* H8/300-Regs:: Register Names
|
|
* H8/300-Addressing:: Addressing Modes
|
|
@end menu
|
|
|
|
@node H8/300-Chars
|
|
@subsection Special Characters
|
|
|
|
@cindex line comment character, H8/300
|
|
@cindex H8/300 line comment character
|
|
@samp{;} is the line comment character.
|
|
|
|
@cindex line separator, H8/300
|
|
@cindex statement separator, H8/300
|
|
@cindex H8/300 line separator
|
|
@samp{$} can be used instead of a newline to separate statements.
|
|
Therefore @emph{you may not use @samp{$} in symbol names} on the H8/300.
|
|
|
|
@node H8/300-Regs
|
|
@subsection Register Names
|
|
|
|
@cindex H8/300 registers
|
|
@cindex registers, H8/300
|
|
You can use predefined symbols of the form @samp{r@var{n}h} and
|
|
@samp{r@var{n}l} to refer to the H8/300 registers as sixteen 8-bit
|
|
general-purpose registers. @var{n} is a digit from @samp{0} to
|
|
@samp{7}); for instance, both @samp{r0h} and @samp{r7l} are valid
|
|
register names.
|
|
|
|
You can also use the eight predefined symbols @samp{r@var{n}} to refer
|
|
to the H8/300 registers as 16-bit registers (you must use this form for
|
|
addressing).
|
|
|
|
The two control registers are called @code{pc} (program counter; a
|
|
16-bit register) and @code{ccr} (condition code register; an 8-bit
|
|
register). @code{r7} is used as the stack pointer, and can also be
|
|
called @code{sp}.
|
|
|
|
@node H8/300-Addressing
|
|
@subsection Addressing Modes
|
|
|
|
@cindex addressing modes, H8/300
|
|
@cindex H8/300 addressing modes
|
|
@value{AS} understands the following addressing modes for the H8/300:
|
|
@table @code
|
|
@item r@var{n}
|
|
Register direct
|
|
|
|
@item @@r@var{n}
|
|
Register indirect
|
|
|
|
@item @@(@var{d}, r@var{n})
|
|
@itemx @@(@var{d}:16, r@var{n})
|
|
Register indirect: 16-bit displacement @var{d} from register @var{n}.
|
|
(You may specify the @samp{:16} for clarity if you wish, but it is not
|
|
required and has no effect.)
|
|
|
|
@item @@r@var{n}+
|
|
Register indirect with post-increment
|
|
|
|
@item @@-r@var{n}
|
|
Register indirect with pre-decrement
|
|
|
|
@item @code{@@}@var{aa}
|
|
@itemx @code{@@}@var{aa}:8
|
|
@itemx @code{@@}@var{aa}:16
|
|
Absolute address @code{aa}. You may specify the @samp{:8} or @samp{:16}
|
|
for clarity, if you wish; but @code{@value{AS}} neither requires this nor
|
|
uses it---the address size required is taken from context.
|
|
|
|
@item #@var{xx}
|
|
@itemx #@var{xx}:8
|
|
@itemx #@var{xx}:16
|
|
Immediate data @var{xx}. You may specify the @samp{:8} or @samp{:16}
|
|
for clarity, if you wish; but @code{@value{AS}} neither requires this nor
|
|
uses it---the data size required is taken from context.
|
|
|
|
@item @code{@@}@code{@@}@var{aa}
|
|
@itemx @code{@@}@code{@@}@var{aa}:8
|
|
Memory indirect. You may specify the @samp{:8} for clarity, if you
|
|
wish; but @code{@value{AS}} neither requires this nor uses it.
|
|
@end table
|
|
|
|
@node H8/300 Floating Point
|
|
@section Floating Point
|
|
|
|
@cindex floating point, H8/300 (@sc{ieee})
|
|
@cindex H8/300 floating point (@sc{ieee})
|
|
The H8/300 family uses @sc{ieee} floating-point numbers.
|
|
|
|
@node H8/300 Directives
|
|
@section H8/300 Machine Directives
|
|
|
|
@cindex H8/300 machine directives (none)
|
|
@cindex machine directives, H8/300 (none)
|
|
@cindex @code{word} directive, H8/300
|
|
@cindex @code{int} directive, H8/300
|
|
@code{@value{AS}} has no machine-dependent directives for the H8/300.
|
|
However, on this platform the @samp{.int} and @samp{.word} directives
|
|
generate 16-bit numbers.
|
|
|
|
@node H8/300 Opcodes
|
|
@section Opcodes
|
|
|
|
@cindex H8/300 opcode summary
|
|
@cindex opcode summary, H8/300
|
|
@cindex mnemonics, H8/300
|
|
@cindex instruction summary, H8/300
|
|
For detailed information on the H8/300 machine instruction set, see
|
|
@cite{H8/300 Series Programming Manual} (Hitachi ADE--602--025).
|
|
|
|
@code{@value{AS}} implements all the standard H8/300 opcodes. No additional
|
|
pseudo-instructions are needed on this family.
|
|
|
|
The following table summarizes the opcodes and their arguments:
|
|
@c kluge due to lack of group outside example
|
|
@page
|
|
@smallexample
|
|
@c In texinfo 2.102, @group makes this doublepsace!!
|
|
@c @group
|
|
@i{Legend:}
|
|
Rs @r{source register}
|
|
Rd @r{destination register}
|
|
imm @r{immediate data}
|
|
x:3 @r{a bit (as a number between 0 and 7)}
|
|
d:8 @r{eight bit displacement from @code{pc}}
|
|
d:16 @r{sixteen bit displacement from @code{Rs}}
|
|
|
|
add.b Rs,Rd biand #x:3,Rd
|
|
add.b #imm:8,Rd biand #x:3,@@Rd
|
|
add.w Rs,Rd biand #x:3,@@aa:8
|
|
adds #1,Rd bild #x:3,Rd
|
|
adds #2,Rd bild #x:3,@@Rd
|
|
addx #imm:8,Rd bild #x:3,@@aa:8
|
|
addx Rs,Rd bior #x:3,Rd
|
|
and #imm:8,Rd bior #x:3,@@Rd
|
|
and Rs,Rd bior #x:3,@@aa:8
|
|
andc #imm:8,ccr bist #x:3,Rd
|
|
band #x:3,Rd bist #x:3,@@Rd
|
|
band #x:3,@@Rd bist #x:3,@@aa:8
|
|
bra d:8 bixor #x:3,Rd
|
|
bt d:8 bixor #x:3,@@Rd
|
|
brn d:8 bixor #x:3,@@aa:8
|
|
bf d:8 bld #x:3,Rd
|
|
bhi d:8 bld #x:3,@@Rd
|
|
bls d:8 bld #x:3,@@aa:8
|
|
bcc d:8 bnot #x:3,Rd
|
|
bhs d:8 bnot #x:3,@@Rd
|
|
bcs d:8 bnot #x:3,@@aa:8
|
|
blo d:8 bnot Rs,Rd
|
|
bne d:8 bnot Rs,@@Rd
|
|
beq d:8 bnot Rs,@@aa:8
|
|
bvc d:8 bor #x:3,Rd
|
|
bvs d:8 bor #x:3,@@Rd
|
|
bpl d:8 bor #x:3,@@aa:8
|
|
bmi d:8 bset #x:3,@@Rd
|
|
bge d:8 bset #x:3,@@aa:8
|
|
blt d:8 bset Rs,Rd
|
|
bgt d:8 bset Rs,@@Rd
|
|
ble d:8 bset Rs,@@aa:8
|
|
bclr #x:3,Rd bsr d:8
|
|
bclr #x:3,@@Rd bst #x:3,Rd
|
|
bclr #x:3,@@aa:8 bst #x:3,@@Rd
|
|
bclr Rs,Rd bst #x:3,@@aa:8
|
|
bclr Rs,@@Rd btst #x:3,Rd
|
|
@c @end group
|
|
@page
|
|
@c @group
|
|
btst #x:3,@@Rd mov.w @@(d:16, Rs),Rd
|
|
btst #x:3,@@aa:8 mov.w @@Rs+,Rd
|
|
btst Rs,Rd mov.w @@aa:16,Rd
|
|
btst Rs,@@Rd mov.w Rs,@@Rd
|
|
btst Rs,@@aa:8 mov.w Rs,@@(d:16, Rd)
|
|
bxor #x:3,Rd mov.w Rs,@@-Rd
|
|
bxor #x:3,@@Rd mov.w Rs,@@aa:16
|
|
bxor #x:3,@@aa:8 movfpe @@aa:16,Rd
|
|
cmp.b #imm:8,Rd movtpe Rs,@@aa:16
|
|
cmp.b Rs,Rd mulxu Rs,Rd
|
|
cmp.w Rs,Rd neg Rs
|
|
daa Rs nop
|
|
das Rs not Rs
|
|
dec Rs or #imm:8,Rd
|
|
divxu Rs,Rd or Rs,Rd
|
|
eepmov orc #imm:8,ccr
|
|
inc Rs pop Rs
|
|
jmp @@Rs push Rs
|
|
jmp @@aa:16 rotl Rs
|
|
jmp @@@@aa rotr Rs
|
|
jsr @@Rs rotxl Rs
|
|
jsr @@aa:16 rotxr Rs
|
|
jsr @@@@aa:8 rte
|
|
ldc #imm:8,ccr rts
|
|
ldc Rs,ccr shal Rs
|
|
mov.b Rs,Rd shar Rs
|
|
mov.b #imm:8,Rd shll Rs
|
|
mov.b @@Rs,Rd shlr Rs
|
|
mov.b @@(d:16, Rs),Rd sleep
|
|
mov.b @@Rs+,Rd stc ccr,Rd
|
|
mov.b @@aa:16,Rd sub.b Rs,Rd
|
|
mov.b @@aa:8,Rd sub.w Rs,Rd
|
|
mov.b Rs,@@Rd subs #1,Rd
|
|
mov.b Rs,@@(d:16, Rd) subs #2,Rd
|
|
mov.b Rs,@@-Rd subx #imm:8,Rd
|
|
mov.b Rs,@@aa:16 subx Rs,Rd
|
|
mov.b Rs,@@aa:8 xor #imm:8,Rd
|
|
mov.w Rs,Rd xor Rs,Rd
|
|
mov.w #imm:16,Rd xorc #imm:8,ccr
|
|
mov.w @@Rs,Rd
|
|
@c @end group
|
|
@end smallexample
|
|
|
|
@cindex size suffixes, H8/300
|
|
@cindex H8/300 size suffixes
|
|
Four H8/300 instructions (@code{add}, @code{cmp}, @code{mov},
|
|
@code{sub}) are defined with variants using the suffixes @samp{.b} and
|
|
@samp{.w} to specify the size of a memory operand. @code{@value{AS}}
|
|
supports these suffixes, but does not require them; since one of the
|
|
operands is always a register, @code{@value{AS}} can deduce the correct size.
|
|
|
|
For example, since @code{r0} refers to a 16-bit register,
|
|
@example
|
|
mov r0,@@foo
|
|
@exdent is equivalent to
|
|
mov.w r0,@@foo
|
|
@end example
|
|
|
|
If you use the size suffixes, @code{@value{AS}} will issue a warning if
|
|
there's a mismatch between the suffix and the register size.
|
|
@end ifset
|
|
|
|
@ifset H8/500
|
|
@page
|
|
@node H8/500-Dependent
|
|
@chapter H8/500 Dependent Features
|
|
|
|
@cindex H8/500 support
|
|
@menu
|
|
* H8/500 Options:: Options
|
|
* H8/500 Syntax:: Syntax
|
|
* H8/500 Floating Point:: Floating Point
|
|
* H8/500 Directives:: H8/500 Machine Directives
|
|
* H8/500 Opcodes:: Opcodes
|
|
@end menu
|
|
|
|
@node H8/500 Options
|
|
@section Options
|
|
|
|
@cindex H8/500 options (none)
|
|
@cindex options, H8/500 (none)
|
|
@code{@value{AS}} has no additional command-line options for the Hitachi
|
|
H8/500 family.
|
|
|
|
@node H8/500 Syntax
|
|
@section Syntax
|
|
|
|
@menu
|
|
* H8/500-Chars:: Special Characters
|
|
* H8/500-Regs:: Register Names
|
|
* H8/500-Addressing:: Addressing Modes
|
|
@end menu
|
|
|
|
@node H8/500-Chars
|
|
@subsection Special Characters
|
|
|
|
@cindex line comment character, H8/500
|
|
@cindex H8/500 line comment character
|
|
@samp{!} is the line comment character.
|
|
|
|
@cindex line separator, H8/500
|
|
@cindex statement separator, H8/500
|
|
@cindex H8/500 line separator
|
|
@samp{;} can be used instead of a newline to separate statements.
|
|
|
|
@cindex symbol names, @samp{$} in
|
|
@cindex @code{$} in symbol names
|
|
Since @samp{$} has no special meaning, you may use it in symbol names.
|
|
|
|
@node H8/500-Regs
|
|
@subsection Register Names
|
|
|
|
@cindex H8/500 registers
|
|
@cindex registers, H8/500
|
|
You can use the predefined symbols @samp{r0}, @samp{r1}, @samp{r2},
|
|
@samp{r3}, @samp{r4}, @samp{r5}, @samp{r6}, and @samp{r7} to refer to
|
|
the H8/500 registers.
|
|
|
|
The H8/500 also has these control registers:
|
|
|
|
@table @code
|
|
@item cp
|
|
code pointer
|
|
|
|
@item dp
|
|
data pointer
|
|
|
|
@item bp
|
|
base pointer
|
|
|
|
@item tp
|
|
stack top pointer
|
|
|
|
@item ep
|
|
extra pointer
|
|
|
|
@item sr
|
|
status register
|
|
|
|
@item ccr
|
|
condition code register
|
|
@end table
|
|
|
|
All registers are 16 bits long. To represent 32 bit numbers, use two
|
|
adjacent registers; for distant memory addresses, use one of the segment
|
|
pointers (@code{cp} for the program counter; @code{dp} for
|
|
@code{r0}--@code{r3}; @code{ep} for @code{r4} and @code{r5}; and
|
|
@code{tp} for @code{r6} and @code{r7}.
|
|
|
|
@node H8/500-Addressing
|
|
@subsection Addressing Modes
|
|
|
|
@cindex addressing modes, H8/500
|
|
@cindex H8/500 addressing modes
|
|
@value{AS} understands the following addressing modes for the H8/500:
|
|
@table @code
|
|
@item R@var{n}
|
|
Register direct
|
|
|
|
@item @@R@var{n}
|
|
Register indirect
|
|
|
|
@item @@(d:8, R@var{n})
|
|
Register indirect with 8 bit signed displacement
|
|
|
|
@item @@(d:16, R@var{n})
|
|
Register indirect with 16 bit signed displacement
|
|
|
|
@item @@-R@var{n}
|
|
Register indirect with pre-decrement
|
|
|
|
@item @@R@var{n}+
|
|
Register indirect with post-increment
|
|
|
|
@item @@@var{aa}:8
|
|
8 bit absolute address
|
|
|
|
@item @@@var{aa}:16
|
|
16 bit absolute address
|
|
|
|
@item #@var{xx}:8
|
|
8 bit immediate
|
|
|
|
@item #@var{xx}:16
|
|
16 bit immediate
|
|
@end table
|
|
|
|
@node H8/500 Floating Point
|
|
@section Floating Point
|
|
|
|
@cindex floating point, H8/500 (@sc{ieee})
|
|
@cindex H8/500 floating point (@sc{ieee})
|
|
The H8/500 family uses @sc{ieee} floating-point numbers.
|
|
|
|
@node H8/500 Directives
|
|
@section H8/500 Machine Directives
|
|
|
|
@cindex H8/500 machine directives (none)
|
|
@cindex machine directives, H8/500 (none)
|
|
@cindex @code{word} directive, H8/500
|
|
@cindex @code{int} directive, H8/500
|
|
@code{@value{AS}} has no machine-dependent directives for the H8/500.
|
|
However, on this platform the @samp{.int} and @samp{.word} directives
|
|
generate 16-bit numbers.
|
|
|
|
@node H8/500 Opcodes
|
|
@section Opcodes
|
|
|
|
@cindex H8/500 opcode summary
|
|
@cindex opcode summary, H8/500
|
|
@cindex mnemonics, H8/500
|
|
@cindex instruction summary, H8/500
|
|
For detailed information on the H8/500 machine instruction set, see
|
|
@cite{H8/500 Series Programming Manual} (Hitachi M21T001).
|
|
|
|
@code{@value{AS}} implements all the standard H8/500 opcodes. No additional
|
|
pseudo-instructions are needed on this family.
|
|
|
|
The following table summarizes H8/500 opcodes and their operands:
|
|
|
|
@c Use @group if it ever works, instead of @page
|
|
@page
|
|
@smallexample
|
|
@i{Legend:}
|
|
abs8 @r{8-bit absolute address}
|
|
abs16 @r{16-bit absolute address}
|
|
abs24 @r{24-bit absolute address}
|
|
crb @r{@code{ccr}, @code{br}, @code{ep}, @code{dp}, @code{tp}, @code{dp}}
|
|
disp8 @r{8-bit displacement}
|
|
ea @r{@code{rn}, @code{@@rn}, @code{@@(d:8, rn)}, @code{@@(d:16, rn)},}
|
|
@r{@code{@@-rn}, @code{@@rn+}, @code{@@aa:8}, @code{@@aa:16},}
|
|
@r{@code{#xx:8}, @code{#xx:16}}
|
|
ea_mem @r{@code{@@rn}, @code{@@(d:8, rn)}, @code{@@(d:16, rn)},}
|
|
@r{@code{@@-rn}, @code{@@rn+}, @code{@@aa:8}, @code{@@aa:16}}
|
|
ea_noimm @r{@code{rn}, @code{@@rn}, @code{@@(d:8, rn)}, @code{@@(d:16, rn)},}
|
|
@r{@code{@@-rn}, @code{@@rn+}, @code{@@aa:8}, @code{@@aa:16}}
|
|
fp r6
|
|
imm4 @r{4-bit immediate data}
|
|
imm8 @r{8-bit immediate data}
|
|
imm16 @r{16-bit immediate data}
|
|
pcrel8 @r{8-bit offset from program counter}
|
|
pcrel16 @r{16-bit offset from program counter}
|
|
qim @r{@code{-2}, @code{-1}, @code{1}, @code{2}}
|
|
rd @r{any register}
|
|
rs @r{a register distinct from rd}
|
|
rlist @r{comma-separated list of registers in parentheses;}
|
|
@r{register ranges @code{rd-rs} are allowed}
|
|
sp @r{stack pointer (@code{r7})}
|
|
sr @r{status register}
|
|
sz @r{size; @samp{.b} or @samp{.w}. If omitted, default @samp{.w}}
|
|
|
|
ldc[.b] ea,crb bcc[.w] pcrel16
|
|
ldc[.w] ea,sr bcc[.b] pcrel8
|
|
add[:q] sz qim,ea_noimm bhs[.w] pcrel16
|
|
add[:g] sz ea,rd bhs[.b] pcrel8
|
|
adds sz ea,rd bcs[.w] pcrel16
|
|
addx sz ea,rd bcs[.b] pcrel8
|
|
and sz ea,rd blo[.w] pcrel16
|
|
andc[.b] imm8,crb blo[.b] pcrel8
|
|
andc[.w] imm16,sr bne[.w] pcrel16
|
|
bpt bne[.b] pcrel8
|
|
bra[.w] pcrel16 beq[.w] pcrel16
|
|
bra[.b] pcrel8 beq[.b] pcrel8
|
|
bt[.w] pcrel16 bvc[.w] pcrel16
|
|
bt[.b] pcrel8 bvc[.b] pcrel8
|
|
brn[.w] pcrel16 bvs[.w] pcrel16
|
|
brn[.b] pcrel8 bvs[.b] pcrel8
|
|
bf[.w] pcrel16 bpl[.w] pcrel16
|
|
bf[.b] pcrel8 bpl[.b] pcrel8
|
|
bhi[.w] pcrel16 bmi[.w] pcrel16
|
|
bhi[.b] pcrel8 bmi[.b] pcrel8
|
|
bls[.w] pcrel16 bge[.w] pcrel16
|
|
bls[.b] pcrel8 bge[.b] pcrel8
|
|
@page
|
|
blt[.w] pcrel16 mov[:g][.b] imm8,ea_mem
|
|
blt[.b] pcrel8 mov[:g][.w] imm16,ea_mem
|
|
bgt[.w] pcrel16 movfpe[.b] ea,rd
|
|
bgt[.b] pcrel8 movtpe[.b] rs,ea_noimm
|
|
ble[.w] pcrel16 mulxu sz ea,rd
|
|
ble[.b] pcrel8 neg sz ea
|
|
bclr sz imm4,ea_noimm nop
|
|
bclr sz rs,ea_noimm not sz ea
|
|
bnot sz imm4,ea_noimm or sz ea,rd
|
|
bnot sz rs,ea_noimm orc[.b] imm8,crb
|
|
bset sz imm4,ea_noimm orc[.w] imm16,sr
|
|
bset sz rs,ea_noimm pjmp abs24
|
|
bsr[.b] pcrel8 pjmp @@rd
|
|
bsr[.w] pcrel16 pjsr abs24
|
|
btst sz imm4,ea_noimm pjsr @@rd
|
|
btst sz rs,ea_noimm prtd imm8
|
|
clr sz ea prtd imm16
|
|
cmp[:e][.b] imm8,rd prts
|
|
cmp[:i][.w] imm16,rd rotl sz ea
|
|
cmp[:g].b imm8,ea_noimm rotr sz ea
|
|
cmp[:g][.w] imm16,ea_noimm rotxl sz ea
|
|
Cmp[:g] sz ea,rd rotxr sz ea
|
|
dadd rs,rd rtd imm8
|
|
divxu sz ea,rd rtd imm16
|
|
dsub rs,rd rts
|
|
exts[.b] rd scb/f rs,pcrel8
|
|
extu[.b] rd scb/ne rs,pcrel8
|
|
jmp @@rd scb/eq rs,pcrel8
|
|
jmp @@(imm8,rd) shal sz ea
|
|
jmp @@(imm16,rd) shar sz ea
|
|
jmp abs16 shll sz ea
|
|
jsr @@rd shlr sz ea
|
|
jsr @@(imm8,rd) sleep
|
|
jsr @@(imm16,rd) stc[.b] crb,ea_noimm
|
|
jsr abs16 stc[.w] sr,ea_noimm
|
|
ldm @@sp+,(rlist) stm (rlist),@@-sp
|
|
link fp,imm8 sub sz ea,rd
|
|
link fp,imm16 subs sz ea,rd
|
|
mov[:e][.b] imm8,rd subx sz ea,rd
|
|
mov[:i][.w] imm16,rd swap[.b] rd
|
|
mov[:l][.w] abs8,rd tas[.b] ea
|
|
mov[:l].b abs8,rd trapa imm4
|
|
mov[:s][.w] rs,abs8 trap/vs
|
|
mov[:s].b rs,abs8 tst sz ea
|
|
mov[:f][.w] @@(disp8,fp),rd unlk fp
|
|
mov[:f][.w] rs,@@(disp8,fp) xch[.w] rs,rd
|
|
mov[:f].b @@(disp8,fp),rd xor sz ea,rd
|
|
mov[:f].b rs,@@(disp8,fp) xorc.b imm8,crb
|
|
mov[:g] sz rs,ea_mem xorc.w imm16,sr
|
|
mov[:g] sz ea,rd
|
|
@end smallexample
|
|
|
|
@end ifset
|
|
@c start Hitachi-SH
|
|
@ifset SH
|
|
@page
|
|
@node SH-Dependent
|
|
@chapter Hitachi SH Dependent Features
|
|
|
|
@cindex SH support
|
|
@menu
|
|
* SH Options:: Options
|
|
* SH Syntax:: Syntax
|
|
* SH Floating Point:: Floating Point
|
|
* SH Directives:: SH Machine Directives
|
|
* SH Opcodes:: Opcodes
|
|
@end menu
|
|
|
|
@node SH Options
|
|
@section Options
|
|
|
|
@cindex SH options (none)
|
|
@cindex options, SH (none)
|
|
@code{@value{AS}} has no additional command-line options for the Hitachi
|
|
SH family.
|
|
|
|
@node SH Syntax
|
|
@section Syntax
|
|
|
|
@menu
|
|
* SH-Chars:: Special Characters
|
|
* SH-Regs:: Register Names
|
|
* SH-Addressing:: Addressing Modes
|
|
@end menu
|
|
|
|
@node SH-Chars
|
|
@subsection Special Characters
|
|
|
|
@cindex line comment character, SH
|
|
@cindex SH line comment character
|
|
@samp{!} is the line comment character.
|
|
|
|
@cindex line separator, SH
|
|
@cindex statement separator, SH
|
|
@cindex SH line separator
|
|
You can use @samp{;} instead of a newline to separate statements.
|
|
|
|
@cindex symbol names, @samp{$} in
|
|
@cindex @code{$} in symbol names
|
|
Since @samp{$} has no special meaning, you may use it in symbol names.
|
|
|
|
@node SH-Regs
|
|
@subsection Register Names
|
|
|
|
@cindex SH registers
|
|
@cindex registers, SH
|
|
You can use the predefined symbols @samp{r0}, @samp{r1}, @samp{r2},
|
|
@samp{r3}, @samp{r4}, @samp{r5}, @samp{r6}, @samp{r7}, @samp{r8},
|
|
@samp{r9}, @samp{r10}, @samp{r11}, @samp{r12}, @samp{r13}, @samp{r14},
|
|
and @samp{r15} to refer to the SH registers.
|
|
|
|
The SH also has these control registers:
|
|
|
|
@table @code
|
|
@item pr
|
|
procedure register (holds return address)
|
|
|
|
@item pc
|
|
program counter
|
|
|
|
@item mach
|
|
@itemx macl
|
|
high and low multiply accumulator registers
|
|
|
|
@item sr
|
|
status register
|
|
|
|
@item gbr
|
|
global base register
|
|
|
|
@item vbr
|
|
vector base register (for interrupt vectors)
|
|
@end table
|
|
|
|
@node SH-Addressing
|
|
@subsection Addressing Modes
|
|
|
|
@cindex addressing modes, SH
|
|
@cindex SH addressing modes
|
|
@code{@value{AS}} understands the following addressing modes for the SH.
|
|
@code{R@var{n}} in the following refers to any of the numbered
|
|
registers, but @emph{not} the control registers.
|
|
|
|
@table @code
|
|
@item R@var{n}
|
|
Register direct
|
|
|
|
@item @@R@var{n}
|
|
Register indirect
|
|
|
|
@item @@-R@var{n}
|
|
Register indirect with pre-decrement
|
|
|
|
@item @@R@var{n}+
|
|
Register indirect with post-increment
|
|
|
|
@item @@(@var{disp}, R@var{n})
|
|
Register indirect with displacement
|
|
|
|
@item @@(R0, R@var{n})
|
|
Register indexed
|
|
|
|
@item @@(@var{disp}, GBR)
|
|
@code{GBR} offset
|
|
|
|
@item @@(R0, GBR)
|
|
GBR indexed
|
|
|
|
@item @var{addr}
|
|
@itemx @@(@var{disp}, PC)
|
|
PC relative address (for branch or for addressing memory). The
|
|
@code{@value{AS}} implementation allows you to use the simpler form
|
|
@var{addr} anywhere a PC relative address is called for; the alternate
|
|
form is supported for compatibility with other assemblers.
|
|
|
|
@item #@var{imm}
|
|
Immediate data
|
|
@end table
|
|
|
|
@node SH Floating Point
|
|
@section Floating Point
|
|
|
|
@cindex floating point, SH (@sc{ieee})
|
|
@cindex SH floating point (@sc{ieee})
|
|
The SH family uses @sc{ieee} floating-point numbers.
|
|
|
|
@node SH Directives
|
|
@section SH Machine Directives
|
|
|
|
@cindex SH machine directives (none)
|
|
@cindex machine directives, SH (none)
|
|
@cindex @code{word} directive, SH
|
|
@cindex @code{int} directive, SH
|
|
@code{@value{AS}} has no machine-dependent directives for the SH.
|
|
|
|
@node SH Opcodes
|
|
@section Opcodes
|
|
|
|
@cindex SH opcode summary
|
|
@cindex opcode summary, SH
|
|
@cindex mnemonics, SH
|
|
@cindex instruction summary, SH
|
|
For detailed information on the SH machine instruction set, see
|
|
@cite{SH-Microcomputer User's Manual} (Hitachi Micro Systems, Inc.).
|
|
|
|
@code{@value{AS}} implements all the standard SH opcodes. No additional
|
|
pseudo-instructions are needed on this family. Note, however, that
|
|
because @code{@value{AS}} supports a simpler form of PC-relative
|
|
addressing, you may simply write (for example)
|
|
|
|
@example
|
|
mov.l bar,r0
|
|
@end example
|
|
|
|
@noindent
|
|
where other assemblers might require an explicit displacement to
|
|
@code{bar} from the program counter:
|
|
|
|
@example
|
|
mov.l @@(@var{disp}, PC)
|
|
@end example
|
|
|
|
Here is a summary of SH opcodes:
|
|
|
|
@page
|
|
@smallexample
|
|
@i{Legend:}
|
|
Rn @r{a numbered register}
|
|
Rm @r{another numbered register}
|
|
#imm @r{immediate data}
|
|
disp @r{displacement}
|
|
disp8 @r{8-bit displacement}
|
|
disp12 @r{12-bit displacement}
|
|
|
|
add #imm,Rn lds.l @@Rn+,PR
|
|
add Rm,Rn mac.w @@Rm+,@@Rn+
|
|
addc Rm,Rn mov #imm,Rn
|
|
addv Rm,Rn mov Rm,Rn
|
|
and #imm,R0 mov.b Rm,@@(R0,Rn)
|
|
and Rm,Rn mov.b Rm,@@-Rn
|
|
and.b #imm,@@(R0,GBR) mov.b Rm,@@Rn
|
|
bf disp8 mov.b @@(disp,Rm),R0
|
|
bra disp12 mov.b @@(disp,GBR),R0
|
|
bsr disp12 mov.b @@(R0,Rm),Rn
|
|
bt disp8 mov.b @@Rm+,Rn
|
|
clrm mov.b @@Rm,Rn
|
|
clrt mov.b R0,@@(disp,Rm)
|
|
cmp/eq #imm,R0 mov.b R0,@@(disp,GBR)
|
|
cmp/eq Rm,Rn mov.l Rm,@@(disp,Rn)
|
|
cmp/ge Rm,Rn mov.l Rm,@@(R0,Rn)
|
|
cmp/gt Rm,Rn mov.l Rm,@@-Rn
|
|
cmp/hi Rm,Rn mov.l Rm,@@Rn
|
|
cmp/hs Rm,Rn mov.l @@(disp,Rn),Rm
|
|
cmp/pl Rn mov.l @@(disp,GBR),R0
|
|
cmp/pz Rn mov.l @@(disp,PC),Rn
|
|
cmp/str Rm,Rn mov.l @@(R0,Rm),Rn
|
|
div0s Rm,Rn mov.l @@Rm+,Rn
|
|
div0u mov.l @@Rm,Rn
|
|
div1 Rm,Rn mov.l R0,@@(disp,GBR)
|
|
exts.b Rm,Rn mov.w Rm,@@(R0,Rn)
|
|
exts.w Rm,Rn mov.w Rm,@@-Rn
|
|
extu.b Rm,Rn mov.w Rm,@@Rn
|
|
extu.w Rm,Rn mov.w @@(disp,Rm),R0
|
|
jmp @@Rn mov.w @@(disp,GBR),R0
|
|
jsr @@Rn mov.w @@(disp,PC),Rn
|
|
ldc Rn,GBR mov.w @@(R0,Rm),Rn
|
|
ldc Rn,SR mov.w @@Rm+,Rn
|
|
ldc Rn,VBR mov.w @@Rm,Rn
|
|
ldc.l @@Rn+,GBR mov.w R0,@@(disp,Rm)
|
|
ldc.l @@Rn+,SR mov.w R0,@@(disp,GBR)
|
|
ldc.l @@Rn+,VBR mova @@(disp,PC),R0
|
|
lds Rn,MACH movt Rn
|
|
lds Rn,MACL muls Rm,Rn
|
|
lds Rn,PR mulu Rm,Rn
|
|
lds.l @@Rn+,MACH neg Rm,Rn
|
|
lds.l @@Rn+,MACL negc Rm,Rn
|
|
@page
|
|
nop stc VBR,Rn
|
|
not Rm,Rn stc.l GBR,@@-Rn
|
|
or #imm,R0 stc.l SR,@@-Rn
|
|
or Rm,Rn stc.l VBR,@@-Rn
|
|
or.b #imm,@@(R0,GBR) sts MACH,Rn
|
|
rotcl Rn sts MACL,Rn
|
|
rotcr Rn sts PR,Rn
|
|
rotl Rn sts.l MACH,@@-Rn
|
|
rotr Rn sts.l MACL,@@-Rn
|
|
rte sts.l PR,@@-Rn
|
|
rts sub Rm,Rn
|
|
sett subc Rm,Rn
|
|
shal Rn subv Rm,Rn
|
|
shar Rn swap.b Rm,Rn
|
|
shll Rn swap.w Rm,Rn
|
|
shll16 Rn tas.b @@Rn
|
|
shll2 Rn trapa #imm
|
|
shll8 Rn tst #imm,R0
|
|
shlr Rn tst Rm,Rn
|
|
shlr16 Rn tst.b #imm,@@(R0,GBR)
|
|
shlr2 Rn xor #imm,R0
|
|
shlr8 Rn xor Rm,Rn
|
|
sleep xor.b #imm,@@(R0,GBR)
|
|
stc GBR,Rn xtrct Rm,Rn
|
|
stc SR,Rn
|
|
@end smallexample
|
|
|
|
@ifset Hitachi-all
|
|
@ifclear GENERIC
|
|
@up
|
|
@end ifclear
|
|
@end ifset
|
|
|
|
@end ifset
|
|
@c end Hitachi-SH
|
|
@ifset I960
|
|
@ifset GENERIC
|
|
@page
|
|
@node i960-Dependent
|
|
@chapter Intel 80960 Dependent Features
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@node Machine Dependencies
|
|
@chapter Intel 80960 Dependent Features
|
|
@end ifclear
|
|
|
|
@cindex i960 support
|
|
@menu
|
|
* Options-i960:: i960 Command-line Options
|
|
* Floating Point-i960:: Floating Point
|
|
* Directives-i960:: i960 Machine Directives
|
|
* Opcodes for i960:: i960 Opcodes
|
|
@end menu
|
|
|
|
@c FIXME! Add Syntax sec with discussion of bitfields here, at least so
|
|
@c long as they're not turned on for other machines than 960.
|
|
|
|
@node Options-i960
|
|
|
|
@section i960 Command-line Options
|
|
|
|
@cindex i960 options
|
|
@cindex options, i960
|
|
@table @code
|
|
|
|
@item -ACA | -ACA_A | -ACB | -ACC | -AKA | -AKB | -AKC | -AMC
|
|
@cindex i960 architecture options
|
|
@cindex architecture options, i960
|
|
@cindex @code{-A} options, i960
|
|
Select the 80960 architecture. Instructions or features not supported
|
|
by the selected architecture cause fatal errors.
|
|
|
|
@samp{-ACA} is equivalent to @samp{-ACA_A}; @samp{-AKC} is equivalent to
|
|
@samp{-AMC}. Synonyms are provided for compatibility with other tools.
|
|
|
|
If none of these options is specified, @code{@value{AS}} will generate code for any
|
|
instruction or feature that is supported by @emph{some} version of the
|
|
960 (even if this means mixing architectures!). In principle,
|
|
@code{@value{AS}} will attempt to deduce the minimal sufficient processor
|
|
type if none is specified; depending on the object code format, the
|
|
processor type may be recorded in the object file. If it is critical
|
|
that the @code{@value{AS}} output match a specific architecture, specify that
|
|
architecture explicitly.
|
|
|
|
@item -b
|
|
@cindex @code{-b} option, i960
|
|
@cindex branch recording, i960
|
|
@cindex i960 branch recording
|
|
Add code to collect information about conditional branches taken, for
|
|
later optimization using branch prediction bits. (The conditional branch
|
|
instructions have branch prediction bits in the CA, CB, and CC
|
|
architectures.) If @var{BR} represents a conditional branch instruction,
|
|
the following represents the code generated by the assembler when
|
|
@samp{-b} is specified:
|
|
|
|
@smallexample
|
|
call @var{increment routine}
|
|
.word 0 # pre-counter
|
|
Label: @var{BR}
|
|
call @var{increment routine}
|
|
.word 0 # post-counter
|
|
@end smallexample
|
|
|
|
The counter following a branch records the number of times that branch
|
|
was @emph{not} taken; the differenc between the two counters is the
|
|
number of times the branch @emph{was} taken.
|
|
|
|
@cindex @code{gbr960}, i960 postprocessor
|
|
@cindex branch statistics table, i960
|
|
A table of every such @code{Label} is also generated, so that the
|
|
external postprocessor @code{gbr960} (supplied by Intel) can locate all
|
|
the counters. This table is always labelled @samp{__BRANCH_TABLE__};
|
|
this is a local symbol to permit collecting statistics for many separate
|
|
object files. The table is word aligned, and begins with a two-word
|
|
header. The first word, initialized to 0, is used in maintaining linked
|
|
lists of branch tables. The second word is a count of the number of
|
|
entries in the table, which follow immediately: each is a word, pointing
|
|
to one of the labels illustrated above.
|
|
|
|
@c TEXI2ROFF-KILL
|
|
@ifinfo
|
|
@c END TEXI2ROFF-KILL
|
|
@example
|
|
+------------+------------+------------+ ... +------------+
|
|
| | | | | |
|
|
| *NEXT | COUNT: N | *BRLAB 1 | | *BRLAB N |
|
|
| | | | | |
|
|
+------------+------------+------------+ ... +------------+
|
|
|
|
__BRANCH_TABLE__ layout
|
|
@end example
|
|
@c TEXI2ROFF-KILL
|
|
@end ifinfo
|
|
@tex
|
|
\vskip 1pc
|
|
\line{\leftskip=0pt\hskip\tableindent
|
|
\boxit{2cm}{\tt *NEXT}\boxit{2cm}{\tt COUNT: \it N}\boxit{2cm}{\tt
|
|
*BRLAB 1}\ibox{1cm}{\quad\dots}\boxit{2cm}{\tt *BRLAB \it N}\hfil}
|
|
\centerline{\it {\tt \_\_BRANCH\_TABLE\_\_} layout}
|
|
@end tex
|
|
@c END TEXI2ROFF-KILL
|
|
|
|
The first word of the header is used to locate multiple branch tables,
|
|
since each object file may contain one. Normally the links are
|
|
maintained with a call to an initialization routine, placed at the
|
|
beginning of each function in the file. The GNU C compiler will
|
|
generate these calls automatically when you give it a @samp{-b} option.
|
|
For further details, see the documentation of @samp{gbr960}.
|
|
|
|
@item -norelax
|
|
@cindex @code{-norelax} option, i960
|
|
Normally, Compare-and-Branch instructions with targets that require
|
|
displacements greater than 13 bits (or that have external targets) are
|
|
replaced with the corresponding compare (or @samp{chkbit}) and branch
|
|
instructions. You can use the @samp{-norelax} option to specify that
|
|
@code{@value{AS}} should generate errors instead, if the target displacement
|
|
is larger than 13 bits.
|
|
|
|
This option does not affect the Compare-and-Jump instructions; the code
|
|
emitted for them is @emph{always} adjusted when necessary (depending on
|
|
displacement size), regardless of whether you use @samp{-norelax}.
|
|
@end table
|
|
|
|
@node Floating Point-i960
|
|
@section Floating Point
|
|
|
|
@cindex floating point, i960 (@sc{ieee})
|
|
@cindex i960 floating point (@sc{ieee})
|
|
@code{@value{AS}} generates @sc{ieee} floating-point numbers for the directives
|
|
@samp{.float}, @samp{.double}, @samp{.extended}, and @samp{.single}.
|
|
|
|
@node Directives-i960
|
|
@section i960 Machine Directives
|
|
|
|
@cindex machine directives, i960
|
|
@cindex i960 machine directives
|
|
|
|
@table @code
|
|
@cindex @code{bss} directive, i960
|
|
@item .bss @var{symbol}, @var{length}, @var{align}
|
|
Reserve @var{length} bytes in the bss section for a local @var{symbol},
|
|
aligned to the power of two specified by @var{align}. @var{length} and
|
|
@var{align} must be positive absolute expressions. This directive
|
|
differs from @samp{.lcomm} only in that it permits you to specify
|
|
an alignment. @xref{Lcomm,,@code{.lcomm}}.
|
|
@end table
|
|
|
|
@table @code
|
|
@item .extended @var{flonums}
|
|
@cindex @code{extended} directive, i960
|
|
@code{.extended} expects zero or more flonums, separated by commas; for
|
|
each flonum, @samp{.extended} emits an @sc{ieee} extended-format (80-bit)
|
|
floating-point number.
|
|
|
|
@item .leafproc @var{call-lab}, @var{bal-lab}
|
|
@cindex @code{leafproc} directive, i960
|
|
You can use the @samp{.leafproc} directive in conjunction with the
|
|
optimized @code{callj} instruction to enable faster calls of leaf
|
|
procedures. If a procedure is known to call no other procedures, you
|
|
may define an entry point that skips procedure prolog code (and that does
|
|
not depend on system-supplied saved context), and declare it as the
|
|
@var{bal-lab} using @samp{.leafproc}. If the procedure also has an
|
|
entry point that goes through the normal prolog, you can specify that
|
|
entry point as @var{call-lab}.
|
|
|
|
A @samp{.leafproc} declaration is meant for use in conjunction with the
|
|
optimized call instruction @samp{callj}; the directive records the data
|
|
needed later to choose between converting the @samp{callj} into a
|
|
@code{bal} or a @code{call}.
|
|
|
|
@var{call-lab} is optional; if only one argument is present, or if the
|
|
two arguments are identical, the single argument is assumed to be the
|
|
@code{bal} entry point.
|
|
|
|
@item .sysproc @var{name}, @var{index}
|
|
@cindex @code{sysproc} directive, i960
|
|
The @samp{.sysproc} directive defines a name for a system procedure.
|
|
After you define it using @samp{.sysproc}, you can use @var{name} to
|
|
refer to the system procedure identified by @var{index} when calling
|
|
procedures with the optimized call instruction @samp{callj}.
|
|
|
|
Both arguments are required; @var{index} must be between 0 and 31
|
|
(inclusive).
|
|
@end table
|
|
|
|
@node Opcodes for i960
|
|
@section i960 Opcodes
|
|
|
|
@cindex opcodes, i960
|
|
@cindex i960 opcodes
|
|
All Intel 960 machine instructions are supported;
|
|
@pxref{Options-i960,,i960 Command-line Options} for a discussion of
|
|
selecting the instruction subset for a particular 960
|
|
architecture.@refill
|
|
|
|
Some opcodes are processed beyond simply emitting a single corresponding
|
|
instruction: @samp{callj}, and Compare-and-Branch or Compare-and-Jump
|
|
instructions with target displacements larger than 13 bits.
|
|
|
|
@menu
|
|
* callj-i960:: @code{callj}
|
|
* Compare-and-branch-i960:: Compare-and-Branch
|
|
@end menu
|
|
|
|
@node callj-i960
|
|
@subsection @code{callj}
|
|
|
|
@cindex @code{callj}, i960 pseudo-opcode
|
|
@cindex i960 @code{callj} pseudo-opcode
|
|
You can write @code{callj} to have the assembler or the linker determine
|
|
the most appropriate form of subroutine call: @samp{call},
|
|
@samp{bal}, or @samp{calls}. If the assembly source contains
|
|
enough information---a @samp{.leafproc} or @samp{.sysproc} directive
|
|
defining the operand---then @code{@value{AS}} will translate the
|
|
@code{callj}; if not, it will simply emit the @code{callj}, leaving it
|
|
for the linker to resolve.
|
|
|
|
@node Compare-and-branch-i960
|
|
@subsection Compare-and-Branch
|
|
|
|
@cindex i960 compare/branch instructions
|
|
@cindex compare/branch instructions, i960
|
|
The 960 architectures provide combined Compare-and-Branch instructions
|
|
that permit you to store the branch target in the lower 13 bits of the
|
|
instruction word itself. However, if you specify a branch target far
|
|
enough away that its address won't fit in 13 bits, the assembler can
|
|
either issue an error, or convert your Compare-and-Branch instruction
|
|
into separate instructions to do the compare and the branch.
|
|
|
|
@cindex compare and jump expansions, i960
|
|
@cindex i960 compare and jump expansions
|
|
Whether @code{@value{AS}} gives an error or expands the instruction depends
|
|
on two choices you can make: whether you use the @samp{-norelax} option,
|
|
and whether you use a ``Compare and Branch'' instruction or a ``Compare
|
|
and Jump'' instruction. The ``Jump'' instructions are @emph{always}
|
|
expanded if necessary; the ``Branch'' instructions are expanded when
|
|
necessary @emph{unless} you specify @code{-norelax}---in which case
|
|
@code{@value{AS}} gives an error instead.
|
|
|
|
These are the Compare-and-Branch instructions, their ``Jump'' variants,
|
|
and the instruction pairs they may expand into:
|
|
|
|
@c TEXI2ROFF-KILL
|
|
@ifinfo
|
|
@c END TEXI2ROFF-KILL
|
|
@example
|
|
Compare and
|
|
Branch Jump Expanded to
|
|
------ ------ ------------
|
|
bbc chkbit; bno
|
|
bbs chkbit; bo
|
|
cmpibe cmpije cmpi; be
|
|
cmpibg cmpijg cmpi; bg
|
|
cmpibge cmpijge cmpi; bge
|
|
cmpibl cmpijl cmpi; bl
|
|
cmpible cmpijle cmpi; ble
|
|
cmpibno cmpijno cmpi; bno
|
|
cmpibne cmpijne cmpi; bne
|
|
cmpibo cmpijo cmpi; bo
|
|
cmpobe cmpoje cmpo; be
|
|
cmpobg cmpojg cmpo; bg
|
|
cmpobge cmpojge cmpo; bge
|
|
cmpobl cmpojl cmpo; bl
|
|
cmpoble cmpojle cmpo; ble
|
|
cmpobne cmpojne cmpo; bne
|
|
@end example
|
|
@c TEXI2ROFF-KILL
|
|
@end ifinfo
|
|
@tex
|
|
\hskip\tableindent
|
|
\halign{\hfil {\tt #}\quad&\hfil {\tt #}\qquad&{\tt #}\hfil\cr
|
|
\omit{\hfil\it Compare and\hfil}\span\omit&\cr
|
|
{\it Branch}&{\it Jump}&{\it Expanded to}\cr
|
|
bbc& & chkbit; bno\cr
|
|
bbs& & chkbit; bo\cr
|
|
cmpibe& cmpije& cmpi; be\cr
|
|
cmpibg& cmpijg& cmpi; bg\cr
|
|
cmpibge& cmpijge& cmpi; bge\cr
|
|
cmpibl& cmpijl& cmpi; bl\cr
|
|
cmpible& cmpijle& cmpi; ble\cr
|
|
cmpibno& cmpijno& cmpi; bno\cr
|
|
cmpibne& cmpijne& cmpi; bne\cr
|
|
cmpibo& cmpijo& cmpi; bo\cr
|
|
cmpobe& cmpoje& cmpo; be\cr
|
|
cmpobg& cmpojg& cmpo; bg\cr
|
|
cmpobge& cmpojge& cmpo; bge\cr
|
|
cmpobl& cmpojl& cmpo; bl\cr
|
|
cmpoble& cmpojle& cmpo; ble\cr
|
|
cmpobne& cmpojne& cmpo; bne\cr}
|
|
@end tex
|
|
@c END TEXI2ROFF-KILL
|
|
@end ifset
|
|
|
|
@ifset M680X0
|
|
@ifset GENERIC
|
|
@page
|
|
@node M68K-Dependent
|
|
@chapter M680x0 Dependent Features
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@node Machine Dependencies
|
|
@chapter M680x0 Dependent Features
|
|
@end ifclear
|
|
|
|
@cindex M680x0 support
|
|
@menu
|
|
* M68K-Opts:: M680x0 Options
|
|
* M68K-Syntax:: Syntax
|
|
* M68K-Float:: Floating Point
|
|
* M68K-Directives:: 680x0 Machine Directives
|
|
* M68K-opcodes:: Opcodes
|
|
@end menu
|
|
|
|
@node M68K-Opts
|
|
@section M680x0 Options
|
|
|
|
@cindex options, M680x0
|
|
@cindex M680x0 options
|
|
The Motorola 680x0 version of @code{@value{AS}} has two machine dependent options.
|
|
One shortens undefined references from 32 to 16 bits, while the
|
|
other is used to tell @code{@value{AS}} what kind of machine it is
|
|
assembling for.
|
|
|
|
@cindex @code{-l} option, M680x0
|
|
You can use the @kbd{-l} option to shorten the size of references to
|
|
undefined symbols. If the @kbd{-l} option is not given, references to
|
|
undefined symbols will be a full long (32 bits) wide. (Since @code{@value{AS}}
|
|
cannot know where these symbols will end up, @code{@value{AS}} can only allocate
|
|
space for the linker to fill in later. Since @code{@value{AS}} doesn't know how
|
|
far away these symbols will be, it allocates as much space as it can.)
|
|
If this option is given, the references will only be one word wide (16
|
|
bits). This may be useful if you want the object file to be as small as
|
|
possible, and you know that the relevant symbols will be less than 17
|
|
bits away.
|
|
|
|
@cindex @code{-m68000} and related options
|
|
@cindex architecture options, M680x0
|
|
@cindex M680x0 architecture options
|
|
The 680x0 version of @code{@value{AS}} is most frequently used to assemble
|
|
programs for the Motorola MC68020 microprocessor. Occasionally it is
|
|
used to assemble programs for the mostly similar, but slightly different
|
|
MC68000 or MC68010 microprocessors. You can give @code{@value{AS}} the options
|
|
@samp{-m68000}, @samp{-mc68000}, @samp{-m68010}, @samp{-mc68010},
|
|
@samp{-m68020}, and @samp{-mc68020} to tell it what processor is the
|
|
target.
|
|
|
|
@node M68K-Syntax
|
|
@section Syntax
|
|
|
|
@cindex M680x0 syntax
|
|
@cindex syntax, M680x0
|
|
@cindex M680x0 size modifiers
|
|
@cindex size modifiers, M680x0
|
|
The 680x0 version of @code{@value{AS}} uses syntax similar to the Sun assembler.
|
|
Size modifiers are appended directly to the end of the opcode without an
|
|
intervening period. For example, write @samp{movl} rather than
|
|
@samp{move.l}.
|
|
|
|
@ifset INTERNALS
|
|
If @code{@value{AS}} is compiled with SUN_ASM_SYNTAX defined, it will also allow
|
|
Sun-style local labels of the form @samp{1$} through @samp{$9}.
|
|
@end ifset
|
|
|
|
In the following table @dfn{apc} stands for any of the address
|
|
registers (@samp{a0} through @samp{a7}), nothing, (@samp{}), the
|
|
Program Counter (@samp{pc}), or the zero-address relative to the
|
|
program counter (@samp{zpc}).
|
|
|
|
@cindex M680x0 addressing modes
|
|
@cindex addressing modes, M680x0
|
|
The following addressing modes are understood:
|
|
@table @dfn
|
|
@item Immediate
|
|
@samp{#@var{digits}}
|
|
|
|
@item Data Register
|
|
@samp{d0} through @samp{d7}
|
|
|
|
@item Address Register
|
|
@samp{a0} through @samp{a7}
|
|
|
|
@item Address Register Indirect
|
|
@samp{a0@@} through @samp{a7@@}
|
|
|
|
@item Address Register Postincrement
|
|
@samp{a0@@+} through @samp{a7@@+}
|
|
|
|
@item Address Register Predecrement
|
|
@samp{a0@@-} through @samp{a7@@-}
|
|
|
|
@item Indirect Plus Offset
|
|
@samp{@var{apc}@@(@var{digits})}
|
|
|
|
@item Index
|
|
@samp{@var{apc}@@(@var{digits},@var{register}:@var{size}:@var{scale})}
|
|
|
|
or @samp{@var{apc}@@(@var{register}:@var{size}:@var{scale})}
|
|
|
|
@item Postindex
|
|
@samp{@var{apc}@@(@var{digits})@@(@var{digits},@var{register}:@var{size}:@var{scale})}
|
|
|
|
or @samp{@var{apc}@@(@var{digits})@@(@var{register}:@var{size}:@var{scale})}
|
|
|
|
@item Preindex
|
|
@samp{@var{apc}@@(@var{digits},@var{register}:@var{size}:@var{scale})@@(@var{digits})}
|
|
|
|
or @samp{@var{apc}@@(@var{register}:@var{size}:@var{scale})@@(@var{digits})}
|
|
|
|
@item Memory Indirect
|
|
@samp{@var{apc}@@(@var{digits})@@(@var{digits})}
|
|
|
|
@item Absolute
|
|
@samp{@var{symbol}}, or @samp{@var{digits}}
|
|
@ignore
|
|
@c pesch@cygnus.com: gnu, rich concur the following needs careful
|
|
@c research before documenting.
|
|
, or either of the above followed
|
|
by @samp{:b}, @samp{:w}, or @samp{:l}.
|
|
@end ignore
|
|
@end table
|
|
|
|
@node M68K-Float
|
|
@section Floating Point
|
|
|
|
@cindex floating point, M680x0
|
|
@cindex M680x0 floating point
|
|
@c FIXME is this "not too well tested" crud STILL true?
|
|
The floating point code is not too well tested, and may have
|
|
subtle bugs in it.
|
|
|
|
Packed decimal (P) format floating literals are not supported.
|
|
Feel free to add the code!
|
|
|
|
The floating point formats generated by directives are these.
|
|
|
|
@table @code
|
|
@item .float
|
|
@cindex @code{float} directive, M680x0
|
|
@code{Single} precision floating point constants.
|
|
|
|
@item .double
|
|
@cindex @code{double} directive, M680x0
|
|
@code{Double} precision floating point constants.
|
|
@end table
|
|
|
|
There is no directive to produce regions of memory holding
|
|
extended precision numbers, however they can be used as
|
|
immediate operands to floating-point instructions. Adding a
|
|
directive to create extended precision numbers would not be
|
|
hard, but it has not yet seemed necessary.
|
|
|
|
@node M68K-Directives
|
|
@section 680x0 Machine Directives
|
|
|
|
@cindex M680x0 directives
|
|
@cindex directives, M680x0
|
|
In order to be compatible with the Sun assembler the 680x0 assembler
|
|
understands the following directives.
|
|
|
|
@table @code
|
|
@item .data1
|
|
@cindex @code{data1} directive, M680x0
|
|
This directive is identical to a @code{.data 1} directive.
|
|
|
|
@item .data2
|
|
@cindex @code{data2} directive, M680x0
|
|
This directive is identical to a @code{.data 2} directive.
|
|
|
|
@item .even
|
|
@cindex @code{even} directive, M680x0
|
|
This directive is identical to a @code{.align 1} directive.
|
|
@c Is this true? does it work???
|
|
|
|
@item .skip
|
|
@cindex @code{skip} directive, M680x0
|
|
This directive is identical to a @code{.space} directive.
|
|
@end table
|
|
|
|
@node M68K-opcodes
|
|
@section Opcodes
|
|
|
|
@cindex M680x0 opcodes
|
|
@cindex opcodes, M680x0
|
|
@cindex instruction set, M680x0
|
|
@c pesch@cygnus.com: I don't see any point in the following
|
|
@c paragraph. Bugs are bugs; how does saying this
|
|
@c help anyone?
|
|
@ignore
|
|
Danger: Several bugs have been found in the opcode table (and
|
|
fixed). More bugs may exist. Be careful when using obscure
|
|
instructions.
|
|
@end ignore
|
|
|
|
@menu
|
|
* M68K-Branch:: Branch Improvement
|
|
* M68K-Chars:: Special Characters
|
|
@end menu
|
|
|
|
@node M68K-Branch
|
|
@subsection Branch Improvement
|
|
|
|
@cindex pseudo-opcodes, M680x0
|
|
@cindex M680x0 pseudo-opcodes
|
|
@cindex branch improvement, M680x0
|
|
@cindex M680x0 branch improvement
|
|
Certain pseudo opcodes are permitted for branch instructions.
|
|
They expand to the shortest branch instruction that will reach the
|
|
target. Generally these mnemonics are made by substituting @samp{j} for
|
|
@samp{b} at the start of a Motorola mnemonic.
|
|
|
|
The following table summarizes the pseudo-operations. A @code{*} flags
|
|
cases that are more fully described after the table:
|
|
|
|
@smallexample
|
|
Displacement
|
|
+-------------------------------------------------
|
|
| 68020 68000/10
|
|
Pseudo-Op |BYTE WORD LONG LONG non-PC relative
|
|
+-------------------------------------------------
|
|
jbsr |bsrs bsr bsrl jsr jsr
|
|
jra |bras bra bral jmp jmp
|
|
* jXX |bXXs bXX bXXl bNXs;jmpl bNXs;jmp
|
|
* dbXX |dbXX dbXX dbXX; bra; jmpl
|
|
* fjXX |fbXXw fbXXw fbXXl fbNXw;jmp
|
|
|
|
XX: condition
|
|
NX: negative of condition XX
|
|
|
|
@end smallexample
|
|
@center @code{*}---see full description below
|
|
|
|
@table @code
|
|
@item jbsr
|
|
@itemx jra
|
|
These are the simplest jump pseudo-operations; they always map to one
|
|
particular machine instruction, depending on the displacement to the
|
|
branch target.
|
|
|
|
@item j@var{XX}
|
|
Here, @samp{j@var{XX}} stands for an entire family of pseudo-operations,
|
|
where @var{XX} is a conditional branch or condition-code test. The full
|
|
list of pseudo-ops in this family is:
|
|
@smallexample
|
|
jhi jls jcc jcs jne jeq jvc
|
|
jvs jpl jmi jge jlt jgt jle
|
|
@end smallexample
|
|
|
|
For the cases of non-PC relative displacements and long displacements on
|
|
the 68000 or 68010, @code{@value{AS}} will issue a longer code fragment in terms of
|
|
@var{NX}, the opposite condition to @var{XX}. For example, for the
|
|
non-PC relative case:
|
|
@smallexample
|
|
j@var{XX} foo
|
|
@end smallexample
|
|
gives
|
|
@smallexample
|
|
b@var{NX}s oof
|
|
jmp foo
|
|
oof:
|
|
@end smallexample
|
|
|
|
@item db@var{XX}
|
|
The full family of pseudo-operations covered here is
|
|
@smallexample
|
|
dbhi dbls dbcc dbcs dbne dbeq dbvc
|
|
dbvs dbpl dbmi dbge dblt dbgt dble
|
|
dbf dbra dbt
|
|
@end smallexample
|
|
|
|
Other than for word and byte displacements, when the source reads
|
|
@samp{db@var{XX} foo}, @code{@value{AS}} will emit
|
|
@smallexample
|
|
db@var{XX} oo1
|
|
bra oo2
|
|
oo1:jmpl foo
|
|
oo2:
|
|
@end smallexample
|
|
|
|
@item fj@var{XX}
|
|
This family includes
|
|
@smallexample
|
|
fjne fjeq fjge fjlt fjgt fjle fjf
|
|
fjt fjgl fjgle fjnge fjngl fjngle fjngt
|
|
fjnle fjnlt fjoge fjogl fjogt fjole fjolt
|
|
fjor fjseq fjsf fjsne fjst fjueq fjuge
|
|
fjugt fjule fjult fjun
|
|
@end smallexample
|
|
|
|
For branch targets that are not PC relative, @code{@value{AS}} emits
|
|
@smallexample
|
|
fb@var{NX} oof
|
|
jmp foo
|
|
oof:
|
|
@end smallexample
|
|
when it encounters @samp{fj@var{XX} foo}.
|
|
|
|
@end table
|
|
|
|
@node M68K-Chars
|
|
@subsection Special Characters
|
|
|
|
@cindex special characters, M680x0
|
|
@cindex M680x0 immediate character
|
|
@cindex immediate character, M680x0
|
|
@cindex M680x0 line comment character
|
|
@cindex line comment character, M680x0
|
|
@cindex comments, M680x0
|
|
The immediate character is @samp{#} for Sun compatibility. The
|
|
line-comment character is @samp{|}. If a @samp{#} appears at the
|
|
beginning of a line, it is treated as a comment unless it looks like
|
|
@samp{# line file}, in which case it is treated normally.
|
|
|
|
@end ifset
|
|
@ignore
|
|
@c FIXME! Stop ignoring when filled in.
|
|
@node 32x32
|
|
@chapter 32x32
|
|
|
|
@section Options
|
|
The 32x32 version of @code{@value{AS}} accepts a @kbd{-m32032} option to
|
|
specify thiat it is compiling for a 32032 processor, or a
|
|
@kbd{-m32532} to specify that it is compiling for a 32532 option.
|
|
The default (if neither is specified) is chosen when the assembler
|
|
is compiled.
|
|
|
|
@section Syntax
|
|
I don't know anything about the 32x32 syntax assembled by
|
|
@code{@value{AS}}. Someone who undersands the processor (I've never seen
|
|
one) and the possible syntaxes should write this section.
|
|
|
|
@section Floating Point
|
|
The 32x32 uses @sc{ieee} floating point numbers, but @code{@value{AS}}
|
|
will only create single or double precision values. I don't know if the
|
|
32x32 understands extended precision numbers.
|
|
|
|
@section 32x32 Machine Directives
|
|
The 32x32 has no machine dependent directives.
|
|
|
|
@end ignore
|
|
@ifset SPARC
|
|
@ifset GENERIC
|
|
@page
|
|
@node Sparc-Dependent
|
|
@chapter SPARC Dependent Features
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@node Machine Dependencies
|
|
@chapter SPARC Dependent Features
|
|
@end ifclear
|
|
|
|
@cindex SPARC support
|
|
@menu
|
|
* Sparc-Opts:: Options
|
|
* Sparc-Float:: Floating Point
|
|
* Sparc-Directives:: Sparc Machine Directives
|
|
@end menu
|
|
|
|
@node Sparc-Opts
|
|
@section Options
|
|
|
|
@cindex options for SPARC
|
|
@cindex SPARC options
|
|
@cindex architectures, SPARC
|
|
@cindex SPARC architectures
|
|
The SPARC chip family includes several successive levels (or other
|
|
variants) of chip, using the same core instruction set, but including
|
|
a few additional instructions at each level.
|
|
|
|
By default, @code{@value{AS}} assumes the core instruction set (SPARC
|
|
v6), but ``bumps'' the architecture level as needed: it switches to
|
|
successively higher architectures as it encounters instructions that
|
|
only exist in the higher levels.
|
|
|
|
@table @code
|
|
@item -Av6 | -Av7 | -Av8 | -Asparclite
|
|
@kindex -Av6
|
|
@kindex Av7
|
|
@kindex -Av8
|
|
@kindex -Asparclite
|
|
Use one of the @samp{-A} options to select one of the SPARC
|
|
architectures explicitly. If you select an architecture explicitly,
|
|
@code{@value{AS}} reports a fatal error if it encounters an instruction
|
|
or feature requiring a higher level.
|
|
|
|
@item -bump
|
|
Permit the assembler to ``bump'' the architecture level as required, but
|
|
warn whenever it is necessary to switch to another level.
|
|
@end table
|
|
|
|
@ignore
|
|
@c FIXME: (sparc) Fill in "syntax" section!
|
|
@c subsection syntax
|
|
I don't know anything about Sparc syntax. Someone who does
|
|
will have to write this section.
|
|
@end ignore
|
|
|
|
@node Sparc-Float
|
|
@section Floating Point
|
|
|
|
@cindex floating point, SPARC (@sc{ieee})
|
|
@cindex SPARC floating point (@sc{ieee})
|
|
The Sparc uses @sc{ieee} floating-point numbers.
|
|
|
|
@node Sparc-Directives
|
|
@section Sparc Machine Directives
|
|
|
|
@cindex SPARC machine directives
|
|
@cindex machine directives, SPARC
|
|
The Sparc version of @code{@value{AS}} supports the following additional
|
|
machine directives:
|
|
|
|
@table @code
|
|
@item .common
|
|
@cindex @code{common} directive, SPARC
|
|
This must be followed by a symbol name, a positive number, and
|
|
@code{"bss"}. This behaves somewhat like @code{.comm}, but the
|
|
syntax is different.
|
|
|
|
@item .half
|
|
@cindex @code{half} directive, SPARC
|
|
This is functionally identical to @code{.short}.
|
|
|
|
@item .proc
|
|
@cindex @code{proc} directive, SPARC
|
|
This directive is ignored. Any text following it on the same
|
|
line is also ignored.
|
|
|
|
@item .reserve
|
|
@cindex @code{reserve} directive, SPARC
|
|
This must be followed by a symbol name, a positive number, and
|
|
@code{"bss"}. This behaves somewhat like @code{.lcomm}, but the
|
|
syntax is different.
|
|
|
|
@item .seg
|
|
@cindex @code{seg} directive, SPARC
|
|
This must be followed by @code{"text"}, @code{"data"}, or
|
|
@code{"data1"}. It behaves like @code{.text}, @code{.data}, or
|
|
@code{.data 1}.
|
|
|
|
@item .skip
|
|
@cindex @code{skip} directive, SPARC
|
|
This is functionally identical to the @code{.space} directive.
|
|
|
|
@item .word
|
|
@cindex @code{word} directive, SPARC
|
|
On the Sparc, the .word directive produces 32 bit values,
|
|
instead of the 16 bit values it produces on many other machines.
|
|
@end table
|
|
|
|
@end ifset
|
|
@ifset I80386
|
|
@ifset GENERIC
|
|
@page
|
|
@node i386-Dependent
|
|
@chapter 80386 Dependent Features
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@node Machine Dependencies
|
|
@chapter 80386 Dependent Features
|
|
@end ifclear
|
|
|
|
@cindex i386 support
|
|
@cindex i80306 support
|
|
@menu
|
|
* i386-Options:: Options
|
|
* i386-Syntax:: AT&T Syntax versus Intel Syntax
|
|
* i386-Opcodes:: Opcode Naming
|
|
* i386-Regs:: Register Naming
|
|
* i386-prefixes:: Opcode Prefixes
|
|
* i386-Memory:: Memory References
|
|
* i386-jumps:: Handling of Jump Instructions
|
|
* i386-Float:: Floating Point
|
|
* i386-Notes:: Notes
|
|
@end menu
|
|
|
|
@node i386-Options
|
|
@section Options
|
|
|
|
@cindex options for i386 (none)
|
|
@cindex i386 options (none)
|
|
The 80386 has no machine dependent options.
|
|
|
|
@node i386-Syntax
|
|
@section AT&T Syntax versus Intel Syntax
|
|
|
|
@cindex i386 syntax compatibility
|
|
@cindex syntax compatibility, i386
|
|
In order to maintain compatibility with the output of @code{@value{GCC}},
|
|
@code{@value{AS}} supports AT&T System V/386 assembler syntax. This is quite
|
|
different from Intel syntax. We mention these differences because
|
|
almost all 80386 documents used only Intel syntax. Notable differences
|
|
between the two syntaxes are:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@cindex immediate operands, i386
|
|
@cindex i386 immediate operands
|
|
@cindex register operands, i386
|
|
@cindex i386 register operands
|
|
@cindex jump/call operands, i386
|
|
@cindex i386 jump/call operands
|
|
@cindex operand delimiters, i386
|
|
AT&T immediate operands are preceded by @samp{$}; Intel immediate
|
|
operands are undelimited (Intel @samp{push 4} is AT&T @samp{pushl $4}).
|
|
AT&T register operands are preceded by @samp{%}; Intel register operands
|
|
are undelimited. AT&T absolute (as opposed to PC relative) jump/call
|
|
operands are prefixed by @samp{*}; they are undelimited in Intel syntax.
|
|
|
|
@item
|
|
@cindex i386 source, destination operands
|
|
@cindex source, destination operands; i386
|
|
AT&T and Intel syntax use the opposite order for source and destination
|
|
operands. Intel @samp{add eax, 4} is @samp{addl $4, %eax}. The
|
|
@samp{source, dest} convention is maintained for compatibility with
|
|
previous Unix assemblers.
|
|
|
|
@item
|
|
@cindex opcode suffixes, i386
|
|
@cindex sizes operands, i386
|
|
@cindex i386 size suffixes
|
|
In AT&T syntax the size of memory operands is determined from the last
|
|
character of the opcode name. Opcode suffixes of @samp{b}, @samp{w},
|
|
and @samp{l} specify byte (8-bit), word (16-bit), and long (32-bit)
|
|
memory references. Intel syntax accomplishes this by prefixes memory
|
|
operands (@emph{not} the opcodes themselves) with @samp{byte ptr},
|
|
@samp{word ptr}, and @samp{dword ptr}. Thus, Intel @samp{mov al, byte
|
|
ptr @var{foo}} is @samp{movb @var{foo}, %al} in AT&T syntax.
|
|
|
|
@item
|
|
@cindex return instructions, i386
|
|
@cindex i386 jump, call, return
|
|
Immediate form long jumps and calls are
|
|
@samp{lcall/ljmp $@var{section}, $@var{offset}} in AT&T syntax; the
|
|
Intel syntax is
|
|
@samp{call/jmp far @var{section}:@var{offset}}. Also, the far return
|
|
instruction
|
|
is @samp{lret $@var{stack-adjust}} in AT&T syntax; Intel syntax is
|
|
@samp{ret far @var{stack-adjust}}.
|
|
|
|
@item
|
|
@cindex sections, i386
|
|
@cindex i386 sections
|
|
The AT&T assembler does not provide support for multiple section
|
|
programs. Unix style systems expect all programs to be single sections.
|
|
@end itemize
|
|
|
|
@node i386-Opcodes
|
|
@section Opcode Naming
|
|
|
|
@cindex i386 opcode naming
|
|
@cindex opcode naming, i386
|
|
Opcode names are suffixed with one character modifiers which specify the
|
|
size of operands. The letters @samp{b}, @samp{w}, and @samp{l} specify
|
|
byte, word, and long operands. If no suffix is specified by an
|
|
instruction and it contains no memory operands then @code{@value{AS}} tries to
|
|
fill in the missing suffix based on the destination register operand
|
|
(the last one by convention). Thus, @samp{mov %ax, %bx} is equivalent
|
|
to @samp{movw %ax, %bx}; also, @samp{mov $1, %bx} is equivalent to
|
|
@samp{movw $1, %bx}. Note that this is incompatible with the AT&T Unix
|
|
assembler which assumes that a missing opcode suffix implies long
|
|
operand size. (This incompatibility does not affect compiler output
|
|
since compilers always explicitly specify the opcode suffix.)
|
|
|
|
Almost all opcodes have the same names in AT&T and Intel format. There
|
|
are a few exceptions. The sign extend and zero extend instructions need
|
|
two sizes to specify them. They need a size to sign/zero extend
|
|
@emph{from} and a size to zero extend @emph{to}. This is accomplished
|
|
by using two opcode suffixes in AT&T syntax. Base names for sign extend
|
|
and zero extend are @samp{movs@dots{}} and @samp{movz@dots{}} in AT&T
|
|
syntax (@samp{movsx} and @samp{movzx} in Intel syntax). The opcode
|
|
suffixes are tacked on to this base name, the @emph{from} suffix before
|
|
the @emph{to} suffix. Thus, @samp{movsbl %al, %edx} is AT&T syntax for
|
|
``move sign extend @emph{from} %al @emph{to} %edx.'' Possible suffixes,
|
|
thus, are @samp{bl} (from byte to long), @samp{bw} (from byte to word),
|
|
and @samp{wl} (from word to long).
|
|
|
|
@cindex conversion instructions, i386
|
|
@cindex i386 conversion instructions
|
|
The Intel-syntax conversion instructions
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@samp{cbw} --- sign-extend byte in @samp{%al} to word in @samp{%ax},
|
|
|
|
@item
|
|
@samp{cwde} --- sign-extend word in @samp{%ax} to long in @samp{%eax},
|
|
|
|
@item
|
|
@samp{cwd} --- sign-extend word in @samp{%ax} to long in @samp{%dx:%ax},
|
|
|
|
@item
|
|
@samp{cdq} --- sign-extend dword in @samp{%eax} to quad in @samp{%edx:%eax},
|
|
@end itemize
|
|
|
|
@noindent
|
|
are called @samp{cbtw}, @samp{cwtl}, @samp{cwtd}, and @samp{cltd} in
|
|
AT&T naming. @code{@value{AS}} accepts either naming for these instructions.
|
|
|
|
@cindex jump instructions, i386
|
|
@cindex call instructions, i386
|
|
Far call/jump instructions are @samp{lcall} and @samp{ljmp} in
|
|
AT&T syntax, but are @samp{call far} and @samp{jump far} in Intel
|
|
convention.
|
|
|
|
@node i386-Regs
|
|
@section Register Naming
|
|
|
|
@cindex i386 registers
|
|
@cindex registers, i386
|
|
Register operands are always prefixes with @samp{%}. The 80386 registers
|
|
consist of
|
|
|
|
@itemize @bullet
|
|
@item
|
|
the 8 32-bit registers @samp{%eax} (the accumulator), @samp{%ebx},
|
|
@samp{%ecx}, @samp{%edx}, @samp{%edi}, @samp{%esi}, @samp{%ebp} (the
|
|
frame pointer), and @samp{%esp} (the stack pointer).
|
|
|
|
@item
|
|
the 8 16-bit low-ends of these: @samp{%ax}, @samp{%bx}, @samp{%cx},
|
|
@samp{%dx}, @samp{%di}, @samp{%si}, @samp{%bp}, and @samp{%sp}.
|
|
|
|
@item
|
|
the 8 8-bit registers: @samp{%ah}, @samp{%al}, @samp{%bh},
|
|
@samp{%bl}, @samp{%ch}, @samp{%cl}, @samp{%dh}, and @samp{%dl} (These
|
|
are the high-bytes and low-bytes of @samp{%ax}, @samp{%bx},
|
|
@samp{%cx}, and @samp{%dx})
|
|
|
|
@item
|
|
the 6 section registers @samp{%cs} (code section), @samp{%ds}
|
|
(data section), @samp{%ss} (stack section), @samp{%es}, @samp{%fs},
|
|
and @samp{%gs}.
|
|
|
|
@item
|
|
the 3 processor control registers @samp{%cr0}, @samp{%cr2}, and
|
|
@samp{%cr3}.
|
|
|
|
@item
|
|
the 6 debug registers @samp{%db0}, @samp{%db1}, @samp{%db2},
|
|
@samp{%db3}, @samp{%db6}, and @samp{%db7}.
|
|
|
|
@item
|
|
the 2 test registers @samp{%tr6} and @samp{%tr7}.
|
|
|
|
@item
|
|
the 8 floating point register stack @samp{%st} or equivalently
|
|
@samp{%st(0)}, @samp{%st(1)}, @samp{%st(2)}, @samp{%st(3)},
|
|
@samp{%st(4)}, @samp{%st(5)}, @samp{%st(6)}, and @samp{%st(7)}.
|
|
@end itemize
|
|
|
|
@node i386-prefixes
|
|
@section Opcode Prefixes
|
|
|
|
@cindex i386 opcode prefixes
|
|
@cindex opcode prefixes, i386
|
|
@cindex prefixes, i386
|
|
Opcode prefixes are used to modify the following opcode. They are used
|
|
to repeat string instructions, to provide section overrides, to perform
|
|
bus lock operations, and to give operand and address size (16-bit
|
|
operands are specified in an instruction by prefixing what would
|
|
normally be 32-bit operands with a ``operand size'' opcode prefix).
|
|
Opcode prefixes are usually given as single-line instructions with no
|
|
operands, and must directly precede the instruction they act upon. For
|
|
example, the @samp{scas} (scan string) instruction is repeated with:
|
|
@smallexample
|
|
repne
|
|
scas
|
|
@end smallexample
|
|
|
|
Here is a list of opcode prefixes:
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@cindex section override prefixes, i386
|
|
Section override prefixes @samp{cs}, @samp{ds}, @samp{ss}, @samp{es},
|
|
@samp{fs}, @samp{gs}. These are automatically added by specifying
|
|
using the @var{section}:@var{memory-operand} form for memory references.
|
|
|
|
@item
|
|
@cindex size prefixes, i386
|
|
Operand/Address size prefixes @samp{data16} and @samp{addr16}
|
|
change 32-bit operands/addresses into 16-bit operands/addresses. Note
|
|
that 16-bit addressing modes (i.e. 8086 and 80286 addressing modes)
|
|
are not supported (yet).
|
|
|
|
@item
|
|
@cindex bus lock prefixes, i386
|
|
@cindex inhibiting interrupts, i386
|
|
The bus lock prefix @samp{lock} inhibits interrupts during
|
|
execution of the instruction it precedes. (This is only valid with
|
|
certain instructions; see a 80386 manual for details).
|
|
|
|
@item
|
|
@cindex coprocessor wait, i386
|
|
The wait for coprocessor prefix @samp{wait} waits for the
|
|
coprocessor to complete the current instruction. This should never be
|
|
needed for the 80386/80387 combination.
|
|
|
|
@item
|
|
@cindex repeat prefixes, i386
|
|
The @samp{rep}, @samp{repe}, and @samp{repne} prefixes are added
|
|
to string instructions to make them repeat @samp{%ecx} times.
|
|
@end itemize
|
|
|
|
@node i386-Memory
|
|
@section Memory References
|
|
|
|
@cindex i386 memory references
|
|
@cindex memory references, i386
|
|
An Intel syntax indirect memory reference of the form
|
|
|
|
@smallexample
|
|
@var{section}:[@var{base} + @var{index}*@var{scale} + @var{disp}]
|
|
@end smallexample
|
|
|
|
@noindent
|
|
is translated into the AT&T syntax
|
|
|
|
@smallexample
|
|
@var{section}:@var{disp}(@var{base}, @var{index}, @var{scale})
|
|
@end smallexample
|
|
|
|
@noindent
|
|
where @var{base} and @var{index} are the optional 32-bit base and
|
|
index registers, @var{disp} is the optional displacement, and
|
|
@var{scale}, taking the values 1, 2, 4, and 8, multiplies @var{index}
|
|
to calculate the address of the operand. If no @var{scale} is
|
|
specified, @var{scale} is taken to be 1. @var{section} specifies the
|
|
optional section register for the memory operand, and may override the
|
|
default section register (see a 80386 manual for section register
|
|
defaults). Note that section overrides in AT&T syntax @emph{must} have
|
|
be preceded by a @samp{%}. If you specify a section override which
|
|
coincides with the default section register, @code{@value{AS}} will @emph{not}
|
|
output any section register override prefixes to assemble the given
|
|
instruction. Thus, section overrides can be specified to emphasize which
|
|
section register is used for a given memory operand.
|
|
|
|
Here are some examples of Intel and AT&T style memory references:
|
|
|
|
@table @asis
|
|
@item AT&T: @samp{-4(%ebp)}, Intel: @samp{[ebp - 4]}
|
|
@var{base} is @samp{%ebp}; @var{disp} is @samp{-4}. @var{section} is
|
|
missing, and the default section is used (@samp{%ss} for addressing with
|
|
@samp{%ebp} as the base register). @var{index}, @var{scale} are both missing.
|
|
|
|
@item AT&T: @samp{foo(,%eax,4)}, Intel: @samp{[foo + eax*4]}
|
|
@var{index} is @samp{%eax} (scaled by a @var{scale} 4); @var{disp} is
|
|
@samp{foo}. All other fields are missing. The section register here
|
|
defaults to @samp{%ds}.
|
|
|
|
@item AT&T: @samp{foo(,1)}; Intel @samp{[foo]}
|
|
This uses the value pointed to by @samp{foo} as a memory operand.
|
|
Note that @var{base} and @var{index} are both missing, but there is only
|
|
@emph{one} @samp{,}. This is a syntactic exception.
|
|
|
|
@item AT&T: @samp{%gs:foo}; Intel @samp{gs:foo}
|
|
This selects the contents of the variable @samp{foo} with section
|
|
register @var{section} being @samp{%gs}.
|
|
@end table
|
|
|
|
Absolute (as opposed to PC relative) call and jump operands must be
|
|
prefixed with @samp{*}. If no @samp{*} is specified, @code{@value{AS}} will
|
|
always choose PC relative addressing for jump/call labels.
|
|
|
|
Any instruction that has a memory operand @emph{must} specify its size (byte,
|
|
word, or long) with an opcode suffix (@samp{b}, @samp{w}, or @samp{l},
|
|
respectively).
|
|
|
|
@node i386-jumps
|
|
@section Handling of Jump Instructions
|
|
|
|
@cindex jump optimization, i386
|
|
@cindex i386 jump optimization
|
|
Jump instructions are always optimized to use the smallest possible
|
|
displacements. This is accomplished by using byte (8-bit) displacement
|
|
jumps whenever the target is sufficiently close. If a byte displacement
|
|
is insufficient a long (32-bit) displacement is used. We do not support
|
|
word (16-bit) displacement jumps (i.e. prefixing the jump instruction
|
|
with the @samp{addr16} opcode prefix), since the 80386 insists upon masking
|
|
@samp{%eip} to 16 bits after the word displacement is added.
|
|
|
|
Note that the @samp{jcxz}, @samp{jecxz}, @samp{loop}, @samp{loopz},
|
|
@samp{loope}, @samp{loopnz} and @samp{loopne} instructions only come in
|
|
byte displacements, so that it is possible that use of these
|
|
instructions (@code{@value{GCC}} does not use them) will cause the assembler to
|
|
print an error message (and generate incorrect code). The AT&T 80386
|
|
assembler tries to get around this problem by expanding @samp{jcxz foo} to
|
|
@smallexample
|
|
jcxz cx_zero
|
|
jmp cx_nonzero
|
|
cx_zero: jmp foo
|
|
cx_nonzero:
|
|
@end smallexample
|
|
|
|
@node i386-Float
|
|
@section Floating Point
|
|
|
|
@cindex i386 floating point
|
|
@cindex floating point, i386
|
|
All 80387 floating point types except packed BCD are supported.
|
|
(BCD support may be added without much difficulty). These data
|
|
types are 16-, 32-, and 64- bit integers, and single (32-bit),
|
|
double (64-bit), and extended (80-bit) precision floating point.
|
|
Each supported type has an opcode suffix and a constructor
|
|
associated with it. Opcode suffixes specify operand's data
|
|
types. Constructors build these data types into memory.
|
|
|
|
@itemize @bullet
|
|
@item
|
|
@cindex @code{float} directive, i386
|
|
@cindex @code{single} directive, i386
|
|
@cindex @code{double} directive, i386
|
|
@cindex @code{tfloat} directive, i386
|
|
Floating point constructors are @samp{.float} or @samp{.single},
|
|
@samp{.double}, and @samp{.tfloat} for 32-, 64-, and 80-bit formats.
|
|
These correspond to opcode suffixes @samp{s}, @samp{l}, and @samp{t}.
|
|
@samp{t} stands for temporary real, and that the 80387 only supports
|
|
this format via the @samp{fldt} (load temporary real to stack top) and
|
|
@samp{fstpt} (store temporary real and pop stack) instructions.
|
|
|
|
@item
|
|
@cindex @code{word} directive, i386
|
|
@cindex @code{long} directive, i386
|
|
@cindex @code{int} directive, i386
|
|
@cindex @code{quad} directive, i386
|
|
Integer constructors are @samp{.word}, @samp{.long} or @samp{.int}, and
|
|
@samp{.quad} for the 16-, 32-, and 64-bit integer formats. The corresponding
|
|
opcode suffixes are @samp{s} (single), @samp{l} (long), and @samp{q}
|
|
(quad). As with the temporary real format the 64-bit @samp{q} format is
|
|
only present in the @samp{fildq} (load quad integer to stack top) and
|
|
@samp{fistpq} (store quad integer and pop stack) instructions.
|
|
@end itemize
|
|
|
|
Register to register operations do not require opcode suffixes,
|
|
so that @samp{fst %st, %st(1)} is equivalent to @samp{fstl %st, %st(1)}.
|
|
|
|
@cindex i386 @code{fwait} instruction
|
|
@cindex @code{fwait instruction}, i386
|
|
Since the 80387 automatically synchronizes with the 80386 @samp{fwait}
|
|
instructions are almost never needed (this is not the case for the
|
|
80286/80287 and 8086/8087 combinations). Therefore, @code{@value{AS}} suppresses
|
|
the @samp{fwait} instruction whenever it is implicitly selected by one
|
|
of the @samp{fn@dots{}} instructions. For example, @samp{fsave} and
|
|
@samp{fnsave} are treated identically. In general, all the @samp{fn@dots{}}
|
|
instructions are made equivalent to @samp{f@dots{}} instructions. If
|
|
@samp{fwait} is desired it must be explicitly coded.
|
|
|
|
@node i386-Notes
|
|
@section Notes
|
|
|
|
@cindex i386 @code{mul}, @code{imul} instructions
|
|
@cindex @code{mul} instruction, i386
|
|
@cindex @code{imul} instruction, i386
|
|
There is some trickery concerning the @samp{mul} and @samp{imul}
|
|
instructions that deserves mention. The 16-, 32-, and 64-bit expanding
|
|
multiplies (base opcode @samp{0xf6}; extension 4 for @samp{mul} and 5
|
|
for @samp{imul}) can be output only in the one operand form. Thus,
|
|
@samp{imul %ebx, %eax} does @emph{not} select the expanding multiply;
|
|
the expanding multiply would clobber the @samp{%edx} register, and this
|
|
would confuse @code{@value{GCC}} output. Use @samp{imul %ebx} to get the
|
|
64-bit product in @samp{%edx:%eax}.
|
|
|
|
We have added a two operand form of @samp{imul} when the first operand
|
|
is an immediate mode expression and the second operand is a register.
|
|
This is just a shorthand, so that, multiplying @samp{%eax} by 69, for
|
|
example, can be done with @samp{imul $69, %eax} rather than @samp{imul
|
|
$69, %eax, %eax}.
|
|
|
|
@end ifset
|
|
@ifset Z8000
|
|
@ifset GENERIC
|
|
@page
|
|
@node Z8000-Dependent
|
|
@chapter Z8000 Dependent Features
|
|
@end ifset
|
|
@ifclear GENERIC
|
|
@node Machine Dependencies
|
|
@chapter Z8000 Dependent Features
|
|
@end ifclear
|
|
|
|
@cindex Z8000 support
|
|
The Z8000 @value{AS} supports both members of the Z8000 family: the
|
|
unsegmented Z8002, with 16 bit addresses, and the segmented Z8001 with
|
|
24 bit addresses.
|
|
|
|
When the assembler is in unsegmented mode (specified with the
|
|
@code{unsegm} directive), an address will take up one word (16 bit)
|
|
sized register. When the assembler is in segmented mode (specified with
|
|
the @code{segm} directive), a 24-bit address takes up a long (32 bit)
|
|
register. @xref{Z8000 Directives,,Assembler Directives for the Z8000},
|
|
for a list of other Z8000 specific assembler directives.
|
|
|
|
@menu
|
|
* Z8000 Options:: No special command-line options for Z8000
|
|
* Z8000 Syntax:: Assembler syntax for the Z8000
|
|
* Z8000 Directives:: Special directives for the Z8000
|
|
* Z8000 Opcodes:: Opcodes
|
|
@end menu
|
|
|
|
@node Z8000 Options
|
|
@section Options
|
|
|
|
@cindex Z8000 options
|
|
@cindex options, Z8000
|
|
@code{@value{AS}} has no additional command-line options for the Zilog
|
|
Z8000 family.
|
|
|
|
@node Z8000 Syntax
|
|
@section Syntax
|
|
@menu
|
|
* Z8000-Chars:: Special Characters
|
|
* Z8000-Regs:: Register Names
|
|
* Z8000-Addressing:: Addressing Modes
|
|
@end menu
|
|
|
|
@node Z8000-Chars
|
|
@subsection Special Characters
|
|
|
|
@cindex line comment character, Z8000
|
|
@cindex Z8000 line comment character
|
|
@samp{!} is the line comment character.
|
|
|
|
@cindex line separator, Z8000
|
|
@cindex statement separator, Z8000
|
|
@cindex Z8000 line separator
|
|
You can use @samp{;} instead of a newline to separate statements.
|
|
|
|
@node Z8000-Regs
|
|
@subsection Register Names
|
|
|
|
@cindex Z8000 registers
|
|
@cindex registers, Z8000
|
|
The Z8000 has sixteen 16 bit registers, numbered 0 to 15. You can refer
|
|
to different sized groups of registers by register number, with the
|
|
prefix @samp{r} for 16 bit registers, @samp{rr} for 32 bit registers and
|
|
@samp{rq} for 64 bit registers. You can also refer to the contents of
|
|
the first eight (of the sixteen 16 bit registers) by bytes. They are
|
|
named @samp{r@var{n}h} and @samp{r@var{n}l}.
|
|
|
|
@smallexample
|
|
@exdent @emph{byte registers}
|
|
r0l r0h r1h r1l r2h r2l r3h r3l
|
|
r4h r4l r5h r5l r6h r6l r7h r7l
|
|
|
|
@exdent @emph{word registers}
|
|
r0 r1 r2 r3 r4 r5 r6 r7 r8 r9 r10 r11 r12 r13 r14 r15
|
|
|
|
@exdent @emph{long word registers}
|
|
rr0 rr2 rr4 rr6 rr8 rr10 rr12 rr14
|
|
|
|
@exdent @emph{quad word registers}
|
|
rq0 rq4 rq8 rq12
|
|
@end smallexample
|
|
|
|
@node Z8000-Addressing
|
|
@subsection Addressing Modes
|
|
|
|
@cindex addressing modes, Z8000
|
|
@cindex Z800 addressing modes
|
|
@value{AS} understands the following addressing modes for the Z8000:
|
|
|
|
@table @code
|
|
@item r@var{n}
|
|
Register direct
|
|
|
|
@item @@r@var{n}
|
|
Indirect register
|
|
|
|
@item @var{addr}
|
|
Direct: the 16 bit or 24 bit address (depending on whether the assembler
|
|
is in segmented or unsegmented mode) of the operand is in the instruction.
|
|
|
|
@item address(r@var{n})
|
|
Indexed: the 16 or 24 bit address is added to the 16 bit register to produce
|
|
the final address in memory of the operand.
|
|
|
|
@item r@var{n}(#@var{imm})
|
|
Base Address: the 16 or 24 bit register is added to the 16 bit sign
|
|
extended immediate displacement to produce the final address in memory
|
|
of the operand.
|
|
|
|
@item r@var{n}(r@var{m})
|
|
Base Index: the 16 or 24 bit register r@var{n} is added to the sign
|
|
extended 16 bit index register r@var{m} to produce the final address in
|
|
memory of the operand.
|
|
|
|
@item #@var{xx}
|
|
Immediate data @var{xx}.
|
|
@end table
|
|
|
|
@node Z8000 Directives
|
|
@section Assembler Directives for the Z8000
|
|
|
|
@cindex Z8000 directives
|
|
@cindex directives, Z8000
|
|
The Z8000 port of @value{AS} includes these additional assembler directives,
|
|
for compatibility with other Z8000 assemblers. As shown, these do not
|
|
begin with @samp{.} (unlike the ordinary @value{AS} directives).
|
|
|
|
@table @code
|
|
@item segm
|
|
@kindex segm
|
|
Generates code for the segmented Z8001.
|
|
|
|
@item unsegm
|
|
@kindex unsegm
|
|
Generates code for the unsegmented Z8002.
|
|
|
|
@item name
|
|
@kindex name
|
|
Synonym for @code{.file}
|
|
|
|
@item global
|
|
@kindex global
|
|
Synonum for @code{.global}
|
|
|
|
@item wval
|
|
@kindex wval
|
|
Synonym for @code{.word}
|
|
|
|
@item lval
|
|
@kindex lval
|
|
Synonym for @code{.long}
|
|
|
|
@item bval
|
|
@kindex bval
|
|
Synonym for @code{.byte}
|
|
|
|
@item sval
|
|
@kindex sval
|
|
Assemble a string. @code{sval} expects one string literal, delimited by
|
|
single quotes. It assembles each byte of the string into consecutive
|
|
addresses. You can use the escape sequence @samp{%@var{xx}} (where
|
|
@var{xx} represents a two-digit hexadecimal number) to represent the
|
|
character whose @sc{ascii} value is @var{xx}. Use this feature to
|
|
describe single quote and other characters that may not appear in string
|
|
literals as themselves. For example, the C statement @w{@samp{char *a =
|
|
"he said \"it's 50% off\"";}} is represented in Z8000 assembly language
|
|
(shown with the assembler output in hex at the left) as
|
|
|
|
@iftex
|
|
@begingroup
|
|
@let@nonarrowing=@comment
|
|
@end iftex
|
|
@smallexample
|
|
68652073 sval 'he said %22it%27s 50%25 off%22%00'
|
|
61696420
|
|
22697427
|
|
73203530
|
|
25206F66
|
|
662200
|
|
@end smallexample
|
|
@iftex
|
|
@endgroup
|
|
@end iftex
|
|
|
|
@item rsect
|
|
@kindex rsect
|
|
synonym for @code{.section}
|
|
|
|
@item block
|
|
@kindex block
|
|
synonym for @code{.space}
|
|
|
|
@item even
|
|
@kindex even
|
|
synonym for @code{.align 1}
|
|
@end table
|
|
|
|
@node Z8000 Opcodes
|
|
@section Opcodes
|
|
|
|
@cindex Z8000 opcode summary
|
|
@cindex opcode summary, Z8000
|
|
@cindex mnemonics, Z8000
|
|
@cindex instruction summary, Z8000
|
|
For detailed information on the Z8000 machine instruction set, see
|
|
@cite{Z8000 Technical Manual}.
|
|
|
|
The following table summarizes the opcodes and their arguments:
|
|
@iftex
|
|
@begingroup
|
|
@let@nonarrowing=@comment
|
|
@end iftex
|
|
@smallexample
|
|
|
|
rs @r{16 bit source register}
|
|
rd @r{16 bit destination register}
|
|
rbs @r{8 bit source register}
|
|
rbd @r{8 bit destination register}
|
|
rrs @r{32 bit source register}
|
|
rrd @r{32 bit destination register}
|
|
rqs @r{64 bit source register}
|
|
rqd @r{64 bit destination register}
|
|
addr @r{16/24 bit address}
|
|
imm @r{immediate data}
|
|
|
|
adc rd,rs clrb addr cpsir @@rd,@@rs,rr,cc
|
|
adcb rbd,rbs clrb addr(rd) cpsirb @@rd,@@rs,rr,cc
|
|
add rd,@@rs clrb rbd dab rbd
|
|
add rd,addr com @@rd dbjnz rbd,disp7
|
|
add rd,addr(rs) com addr dec @@rd,imm4m1
|
|
add rd,imm16 com addr(rd) dec addr(rd),imm4m1
|
|
add rd,rs com rd dec addr,imm4m1
|
|
addb rbd,@@rs comb @@rd dec rd,imm4m1
|
|
addb rbd,addr comb addr decb @@rd,imm4m1
|
|
addb rbd,addr(rs) comb addr(rd) decb addr(rd),imm4m1
|
|
addb rbd,imm8 comb rbd decb addr,imm4m1
|
|
addb rbd,rbs comflg flags decb rbd,imm4m1
|
|
addl rrd,@@rs cp @@rd,imm16 di i2
|
|
addl rrd,addr cp addr(rd),imm16 div rrd,@@rs
|
|
addl rrd,addr(rs) cp addr,imm16 div rrd,addr
|
|
addl rrd,imm32 cp rd,@@rs div rrd,addr(rs)
|
|
addl rrd,rrs cp rd,addr div rrd,imm16
|
|
and rd,@@rs cp rd,addr(rs) div rrd,rs
|
|
and rd,addr cp rd,imm16 divl rqd,@@rs
|
|
and rd,addr(rs) cp rd,rs divl rqd,addr
|
|
and rd,imm16 cpb @@rd,imm8 divl rqd,addr(rs)
|
|
and rd,rs cpb addr(rd),imm8 divl rqd,imm32
|
|
andb rbd,@@rs cpb addr,imm8 divl rqd,rrs
|
|
andb rbd,addr cpb rbd,@@rs djnz rd,disp7
|
|
andb rbd,addr(rs) cpb rbd,addr ei i2
|
|
andb rbd,imm8 cpb rbd,addr(rs) ex rd,@@rs
|
|
andb rbd,rbs cpb rbd,imm8 ex rd,addr
|
|
bit @@rd,imm4 cpb rbd,rbs ex rd,addr(rs)
|
|
bit addr(rd),imm4 cpd rd,@@rs,rr,cc ex rd,rs
|
|
bit addr,imm4 cpdb rbd,@@rs,rr,cc exb rbd,@@rs
|
|
bit rd,imm4 cpdr rd,@@rs,rr,cc exb rbd,addr
|
|
bit rd,rs cpdrb rbd,@@rs,rr,cc exb rbd,addr(rs)
|
|
bitb @@rd,imm4 cpi rd,@@rs,rr,cc exb rbd,rbs
|
|
bitb addr(rd),imm4 cpib rbd,@@rs,rr,cc ext0e imm8
|
|
bitb addr,imm4 cpir rd,@@rs,rr,cc ext0f imm8
|
|
bitb rbd,imm4 cpirb rbd,@@rs,rr,cc ext8e imm8
|
|
bitb rbd,rs cpl rrd,@@rs ext8f imm8
|
|
bpt cpl rrd,addr exts rrd
|
|
call @@rd cpl rrd,addr(rs) extsb rd
|
|
call addr cpl rrd,imm32 extsl rqd
|
|
call addr(rd) cpl rrd,rrs halt
|
|
calr disp12 cpsd @@rd,@@rs,rr,cc in rd,@@rs
|
|
clr @@rd cpsdb @@rd,@@rs,rr,cc in rd,imm16
|
|
clr addr cpsdr @@rd,@@rs,rr,cc inb rbd,@@rs
|
|
clr addr(rd) cpsdrb @@rd,@@rs,rr,cc inb rbd,imm16
|
|
clr rd cpsi @@rd,@@rs,rr,cc inc @@rd,imm4m1
|
|
clrb @@rd cpsib @@rd,@@rs,rr,cc inc addr(rd),imm4m1
|
|
inc addr,imm4m1 ldb rbd,rs(rx) mult rrd,addr(rs)
|
|
inc rd,imm4m1 ldb rd(imm16),rbs mult rrd,imm16
|
|
incb @@rd,imm4m1 ldb rd(rx),rbs mult rrd,rs
|
|
incb addr(rd),imm4m1 ldctl ctrl,rs multl rqd,@@rs
|
|
incb addr,imm4m1 ldctl rd,ctrl multl rqd,addr
|
|
incb rbd,imm4m1 ldd @@rs,@@rd,rr multl rqd,addr(rs)
|
|
ind @@rd,@@rs,ra lddb @@rs,@@rd,rr multl rqd,imm32
|
|
indb @@rd,@@rs,rba lddr @@rs,@@rd,rr multl rqd,rrs
|
|
inib @@rd,@@rs,ra lddrb @@rs,@@rd,rr neg @@rd
|
|
inibr @@rd,@@rs,ra ldi @@rd,@@rs,rr neg addr
|
|
iret ldib @@rd,@@rs,rr neg addr(rd)
|
|
jp cc,@@rd ldir @@rd,@@rs,rr neg rd
|
|
jp cc,addr ldirb @@rd,@@rs,rr negb @@rd
|
|
jp cc,addr(rd) ldk rd,imm4 negb addr
|
|
jr cc,disp8 ldl @@rd,rrs negb addr(rd)
|
|
ld @@rd,imm16 ldl addr(rd),rrs negb rbd
|
|
ld @@rd,rs ldl addr,rrs nop
|
|
ld addr(rd),imm16 ldl rd(imm16),rrs or rd,@@rs
|
|
ld addr(rd),rs ldl rd(rx),rrs or rd,addr
|
|
ld addr,imm16 ldl rrd,@@rs or rd,addr(rs)
|
|
ld addr,rs ldl rrd,addr or rd,imm16
|
|
ld rd(imm16),rs ldl rrd,addr(rs) or rd,rs
|
|
ld rd(rx),rs ldl rrd,imm32 orb rbd,@@rs
|
|
ld rd,@@rs ldl rrd,rrs orb rbd,addr
|
|
ld rd,addr ldl rrd,rs(imm16) orb rbd,addr(rs)
|
|
ld rd,addr(rs) ldl rrd,rs(rx) orb rbd,imm8
|
|
ld rd,imm16 ldm @@rd,rs,n orb rbd,rbs
|
|
ld rd,rs ldm addr(rd),rs,n out @@rd,rs
|
|
ld rd,rs(imm16) ldm addr,rs,n out imm16,rs
|
|
ld rd,rs(rx) ldm rd,@@rs,n outb @@rd,rbs
|
|
lda rd,addr ldm rd,addr(rs),n outb imm16,rbs
|
|
lda rd,addr(rs) ldm rd,addr,n outd @@rd,@@rs,ra
|
|
lda rd,rs(imm16) ldps @@rs outdb @@rd,@@rs,rba
|
|
lda rd,rs(rx) ldps addr outib @@rd,@@rs,ra
|
|
ldar rd,disp16 ldps addr(rs) outibr @@rd,@@rs,ra
|
|
ldb @@rd,imm8 ldr disp16,rs pop @@rd,@@rs
|
|
ldb @@rd,rbs ldr rd,disp16 pop addr(rd),@@rs
|
|
ldb addr(rd),imm8 ldrb disp16,rbs pop addr,@@rs
|
|
ldb addr(rd),rbs ldrb rbd,disp16 pop rd,@@rs
|
|
ldb addr,imm8 ldrl disp16,rrs popl @@rd,@@rs
|
|
ldb addr,rbs ldrl rrd,disp16 popl addr(rd),@@rs
|
|
ldb rbd,@@rs mbit popl addr,@@rs
|
|
ldb rbd,addr mreq rd popl rrd,@@rs
|
|
ldb rbd,addr(rs) mres push @@rd,@@rs
|
|
ldb rbd,imm8 mset push @@rd,addr
|
|
ldb rbd,rbs mult rrd,@@rs push @@rd,addr(rs)
|
|
ldb rbd,rs(imm16) mult rrd,addr push @@rd,imm16
|
|
push @@rd,rs set addr,imm4 subl rrd,imm32
|
|
pushl @@rd,@@rs set rd,imm4 subl rrd,rrs
|
|
pushl @@rd,addr set rd,rs tcc cc,rd
|
|
pushl @@rd,addr(rs) setb @@rd,imm4 tccb cc,rbd
|
|
pushl @@rd,rrs setb addr(rd),imm4 test @@rd
|
|
res @@rd,imm4 setb addr,imm4 test addr
|
|
res addr(rd),imm4 setb rbd,imm4 test addr(rd)
|
|
res addr,imm4 setb rbd,rs test rd
|
|
res rd,imm4 setflg imm4 testb @@rd
|
|
res rd,rs sinb rbd,imm16 testb addr
|
|
resb @@rd,imm4 sinb rd,imm16 testb addr(rd)
|
|
resb addr(rd),imm4 sind @@rd,@@rs,ra testb rbd
|
|
resb addr,imm4 sindb @@rd,@@rs,rba testl @@rd
|
|
resb rbd,imm4 sinib @@rd,@@rs,ra testl addr
|
|
resb rbd,rs sinibr @@rd,@@rs,ra testl addr(rd)
|
|
resflg imm4 sla rd,imm8 testl rrd
|
|
ret cc slab rbd,imm8 trdb @@rd,@@rs,rba
|
|
rl rd,imm1or2 slal rrd,imm8 trdrb @@rd,@@rs,rba
|
|
rlb rbd,imm1or2 sll rd,imm8 trib @@rd,@@rs,rbr
|
|
rlc rd,imm1or2 sllb rbd,imm8 trirb @@rd,@@rs,rbr
|
|
rlcb rbd,imm1or2 slll rrd,imm8 trtdrb @@ra,@@rb,rbr
|
|
rldb rbb,rba sout imm16,rs trtib @@ra,@@rb,rr
|
|
rr rd,imm1or2 soutb imm16,rbs trtirb @@ra,@@rb,rbr
|
|
rrb rbd,imm1or2 soutd @@rd,@@rs,ra trtrb @@ra,@@rb,rbr
|
|
rrc rd,imm1or2 soutdb @@rd,@@rs,rba tset @@rd
|
|
rrcb rbd,imm1or2 soutib @@rd,@@rs,ra tset addr
|
|
rrdb rbb,rba soutibr @@rd,@@rs,ra tset addr(rd)
|
|
rsvd36 sra rd,imm8 tset rd
|
|
rsvd38 srab rbd,imm8 tsetb @@rd
|
|
rsvd78 sral rrd,imm8 tsetb addr
|
|
rsvd7e srl rd,imm8 tsetb addr(rd)
|
|
rsvd9d srlb rbd,imm8 tsetb rbd
|
|
rsvd9f srll rrd,imm8 xor rd,@@rs
|
|
rsvdb9 sub rd,@@rs xor rd,addr
|
|
rsvdbf sub rd,addr xor rd,addr(rs)
|
|
sbc rd,rs sub rd,addr(rs) xor rd,imm16
|
|
sbcb rbd,rbs sub rd,imm16 xor rd,rs
|
|
sc imm8 sub rd,rs xorb rbd,@@rs
|
|
sda rd,rs subb rbd,@@rs xorb rbd,addr
|
|
sdab rbd,rs subb rbd,addr xorb rbd,addr(rs)
|
|
sdal rrd,rs subb rbd,addr(rs) xorb rbd,imm8
|
|
sdl rd,rs subb rbd,imm8 xorb rbd,rbs
|
|
sdlb rbd,rs subb rbd,rbs xorb rbd,rbs
|
|
sdll rrd,rs subl rrd,@@rs
|
|
set @@rd,imm4 subl rrd,addr
|
|
set addr(rd),imm4 subl rrd,addr(rs)
|
|
@end smallexample
|
|
@iftex
|
|
@endgroup
|
|
@end iftex
|
|
|
|
@end ifset
|
|
@ifset GENERIC
|
|
@c reverse effect of @down at top of generic Machine-Dep chapter
|
|
@up
|
|
@end ifset
|
|
|
|
@ignore
|
|
@c pesch@cygnus.com: we ignore the following chapters, since internals are
|
|
@c changing rapidly. These may need to be moved to another
|
|
@c book anyhow, if we adopt the model of user/modifier
|
|
@c books.
|
|
@node Maintenance
|
|
@chapter Maintaining the Assembler
|
|
[[this chapter is still being built]]
|
|
|
|
@section Design
|
|
We had these goals, in descending priority:
|
|
@table @b
|
|
@item Accuracy.
|
|
For every program composed by a compiler, @code{@value{AS}} should emit
|
|
``correct'' code. This leaves some latitude in choosing addressing
|
|
modes, order of @code{relocation_info} structures in the object
|
|
file, @emph{etc}.
|
|
|
|
@item Speed, for usual case.
|
|
By far the most common use of @code{@value{AS}} will be assembling compiler
|
|
emissions.
|
|
|
|
@item Upward compatibility for existing assembler code.
|
|
Well @dots{} we don't support Vax bit fields but everything else
|
|
seems to be upward compatible.
|
|
|
|
@item Readability.
|
|
The code should be maintainable with few surprises. (JF: ha!)
|
|
|
|
@end table
|
|
|
|
We assumed that disk I/O was slow and expensive while memory was
|
|
fast and access to memory was cheap. We expect the in-memory data
|
|
structures to be less than 10 times the size of the emitted object
|
|
file. (Contrast this with the C compiler where in-memory structures
|
|
might be 100 times object file size!)
|
|
This suggests:
|
|
@itemize @bullet
|
|
@item
|
|
Try to read the source file from disk only one time. For other
|
|
reasons, we keep large chunks of the source file in memory during
|
|
assembly so this is not a problem. Also the assembly algorithm
|
|
should only scan the source text once if the compiler composed the
|
|
text according to a few simple rules.
|
|
@item
|
|
Emit the object code bytes only once. Don't store values and then
|
|
backpatch later.
|
|
@item
|
|
Build the object file in memory and do direct writes to disk of
|
|
large buffers.
|
|
@end itemize
|
|
|
|
RMS suggested a one-pass algorithm which seems to work well. By not
|
|
parsing text during a second pass considerable time is saved on
|
|
large programs (@emph{e.g.} the sort of C program @code{yacc} would
|
|
emit).
|
|
|
|
It happened that the data structures needed to emit relocation
|
|
information to the object file were neatly subsumed into the data
|
|
structures that do backpatching of addresses after pass 1.
|
|
|
|
Many of the functions began life as re-usable modules, loosely
|
|
connected. RMS changed this to gain speed. For example, input
|
|
parsing routines which used to work on pre-sanitized strings now
|
|
must parse raw data. Hence they have to import knowledge of the
|
|
assemblers' comment conventions @emph{etc}.
|
|
|
|
@section Deprecated Feature(?)s
|
|
We have stopped supporting some features:
|
|
@itemize @bullet
|
|
@item
|
|
@code{.org} statements must have @b{defined} expressions.
|
|
@item
|
|
Vax Bit fields (@kbd{:} operator) are entirely unsupported.
|
|
@end itemize
|
|
|
|
It might be a good idea to not support these features in a future release:
|
|
@itemize @bullet
|
|
@item
|
|
@kbd{#} should begin a comment, even in column 1.
|
|
@item
|
|
Why support the logical line & file concept any more?
|
|
@item
|
|
Subsections are a good candidate for flushing.
|
|
Depends on which compilers need them I guess.
|
|
@end itemize
|
|
|
|
@section Bugs, Ideas, Further Work
|
|
Clearly the major improvement is DON'T USE A TEXT-READING
|
|
ASSEMBLER for the back end of a compiler. It is much faster to
|
|
interpret binary gobbledygook from a compiler's tables than to
|
|
ask the compiler to write out human-readable code just so the
|
|
assembler can parse it back to binary.
|
|
|
|
Assuming you use @code{@value{AS}} for human written programs: here are
|
|
some ideas:
|
|
@itemize @bullet
|
|
@item
|
|
Document (here) @code{APP}.
|
|
@item
|
|
Take advantage of knowing no spaces except after opcode
|
|
to speed up @code{@value{AS}}. (Modify @code{app.c} to flush useless spaces:
|
|
only keep space/tabs at begin of line or between 2
|
|
symbols.)
|
|
@item
|
|
Put pointers in this documentation to @file{a.out} documentation.
|
|
@item
|
|
Split the assembler into parts so it can gobble direct binary
|
|
from @emph{e.g.} @code{cc}. It is silly for@code{cc} to compose text
|
|
just so @code{@value{AS}} can parse it back to binary.
|
|
@item
|
|
Rewrite hash functions: I want a more modular, faster library.
|
|
@item
|
|
Clean up LOTS of code.
|
|
@item
|
|
Include all the non-@file{.c} files in the maintenance chapter.
|
|
@item
|
|
Document flonums.
|
|
@item
|
|
Implement flonum short literals.
|
|
@item
|
|
Change all talk of expression operands to expression quantities,
|
|
or perhaps to expression arguments.
|
|
@item
|
|
Implement pass 2.
|
|
@item
|
|
Whenever a @code{.text} or @code{.data} statement is seen, we close
|
|
of the current frag with an imaginary @code{.fill 0}. This is
|
|
because we only have one obstack for frags, and we can't grow new
|
|
frags for a new subsection, then go back to the old subsection and
|
|
append bytes to the old frag. All this nonsense goes away if we
|
|
give each subsection its own obstack. It makes code simpler in
|
|
about 10 places, but nobody has bothered to do it because C compiler
|
|
output rarely changes subsections (compared to ending frags with
|
|
relaxable addresses, which is common).
|
|
@end itemize
|
|
|
|
@section Sources
|
|
@c The following files in the @file{@value{AS}} directory
|
|
@c are symbolic links to other files, of
|
|
@c the same name, in a different directory.
|
|
@c @itemize @bullet
|
|
@c @item
|
|
@c @file{atof_generic.c}
|
|
@c @item
|
|
@c @file{atof_vax.c}
|
|
@c @item
|
|
@c @file{flonum_const.c}
|
|
@c @item
|
|
@c @file{flonum_copy.c}
|
|
@c @item
|
|
@c @file{flonum_get.c}
|
|
@c @item
|
|
@c @file{flonum_multip.c}
|
|
@c @item
|
|
@c @file{flonum_normal.c}
|
|
@c @item
|
|
@c @file{flonum_print.c}
|
|
@c @end itemize
|
|
|
|
Here is a list of the source files in the @file{@value{AS}} directory.
|
|
|
|
@table @file
|
|
@item app.c
|
|
This contains the pre-processing phase, which deletes comments,
|
|
handles whitespace, etc. This was recently re-written, since app
|
|
used to be a separate program, but RMS wanted it to be inline.
|
|
|
|
@item append.c
|
|
This is a subroutine to append a string to another string returning a
|
|
pointer just after the last @code{char} appended. (JF: All these
|
|
little routines should probably all be put in one file.)
|
|
|
|
@item as.c
|
|
Here you will find the main program of the assembler @code{@value{AS}}.
|
|
|
|
@item expr.c
|
|
This is a branch office of @file{read.c}. This understands
|
|
expressions, arguments. Inside @code{@value{AS}}, arguments are called
|
|
(expression) @emph{operands}. This is confusing, because we also talk
|
|
(elsewhere) about instruction @emph{operands}. Also, expression
|
|
operands are called @emph{quantities} explicitly to avoid confusion
|
|
with instruction operands. What a mess.
|
|
|
|
@item frags.c
|
|
This implements the @b{frag} concept. Without frags, finding the
|
|
right size for branch instructions would be a lot harder.
|
|
|
|
@item hash.c
|
|
This contains the symbol table, opcode table @emph{etc.} hashing
|
|
functions.
|
|
|
|
@item hex_value.c
|
|
This is a table of values of digits, for use in atoi() type
|
|
functions. Could probably be flushed by using calls to strtol(), or
|
|
something similar.
|
|
|
|
@item input-file.c
|
|
This contains Operating system dependent source file reading
|
|
routines. Since error messages often say where we are in reading
|
|
the source file, they live here too. Since @code{@value{AS}} is intended to
|
|
run under GNU and Unix only, this might be worth flushing. Anyway,
|
|
almost all C compilers support stdio.
|
|
|
|
@item input-scrub.c
|
|
This deals with calling the pre-processor (if needed) and feeding the
|
|
chunks back to the rest of the assembler the right way.
|
|
|
|
@item messages.c
|
|
This contains operating system independent parts of fatal and
|
|
warning message reporting. See @file{append.c} above.
|
|
|
|
@item output-file.c
|
|
This contains operating system dependent functions that write an
|
|
object file for @code{@value{AS}}. See @file{input-file.c} above.
|
|
|
|
@item read.c
|
|
This implements all the directives of @code{@value{AS}}. This also deals
|
|
with passing input lines to the machine dependent part of the
|
|
assembler.
|
|
|
|
@item strstr.c
|
|
This is a C library function that isn't in most C libraries yet.
|
|
See @file{append.c} above.
|
|
|
|
@item subsegs.c
|
|
This implements subsections.
|
|
|
|
@item symbols.c
|
|
This implements symbols.
|
|
|
|
@item write.c
|
|
This contains the code to perform relaxation, and to write out
|
|
the object file. It is mostly operating system independent, but
|
|
different OSes have different object file formats in any case.
|
|
|
|
@item xmalloc.c
|
|
This implements @code{malloc()} or bust. See @file{append.c} above.
|
|
|
|
@item xrealloc.c
|
|
This implements @code{realloc()} or bust. See @file{append.c} above.
|
|
|
|
@item atof-generic.c
|
|
The following files were taken from a machine-independent subroutine
|
|
library for manipulating floating point numbers and very large
|
|
integers.
|
|
|
|
@file{atof-generic.c} turns a string into a flonum internal format
|
|
floating-point number.
|
|
|
|
@item flonum-const.c
|
|
This contains some potentially useful floating point numbers in
|
|
flonum format.
|
|
|
|
@item flonum-copy.c
|
|
This copies a flonum.
|
|
|
|
@item flonum-multip.c
|
|
This multiplies two flonums together.
|
|
|
|
@item bignum-copy.c
|
|
This copies a bignum.
|
|
|
|
@end table
|
|
|
|
Here is a table of all the machine-specific files (this includes
|
|
both source and header files). Typically, there is a
|
|
@var{machine}.c file, a @var{machine}-opcode.h file, and an
|
|
atof-@var{machine}.c file. The @var{machine}-opcode.h file should
|
|
be identical to the one used by GDB (which uses it for disassembly.)
|
|
|
|
@table @file
|
|
|
|
@item atof-ieee.c
|
|
This contains code to turn a flonum into a ieee literal constant.
|
|
This is used by tye 680x0, 32x32, sparc, and i386 versions of @code{@value{AS}}.
|
|
|
|
@item i386-opcode.h
|
|
This is the opcode-table for the i386 version of the assembler.
|
|
|
|
@item i386.c
|
|
This contains all the code for the i386 version of the assembler.
|
|
|
|
@item i386.h
|
|
This defines constants and macros used by the i386 version of the assembler.
|
|
|
|
@item m-generic.h
|
|
generic 68020 header file. To be linked to m68k.h on a
|
|
non-sun3, non-hpux system.
|
|
|
|
@item m-sun2.h
|
|
68010 header file for Sun2 workstations. Not well tested. To be linked
|
|
to m68k.h on a sun2. (See also @samp{-DSUN_ASM_SYNTAX} in the
|
|
@file{Makefile}.)
|
|
|
|
@item m-sun3.h
|
|
68020 header file for Sun3 workstations. To be linked to m68k.h before
|
|
compiling on a Sun3 system. (See also @samp{-DSUN_ASM_SYNTAX} in the
|
|
@file{Makefile}.)
|
|
|
|
@item m-hpux.h
|
|
68020 header file for a HPUX (system 5?) box. Which box, which
|
|
version of HPUX, etc? I don't know.
|
|
|
|
@item m68k.h
|
|
A hard- or symbolic- link to one of @file{m-generic.h},
|
|
@file{m-hpux.h} or @file{m-sun3.h} depending on which kind of
|
|
680x0 you are assembling for. (See also @samp{-DSUN_ASM_SYNTAX} in the
|
|
@file{Makefile}.)
|
|
|
|
@item m68k-opcode.h
|
|
Opcode table for 68020. This is now a link to the opcode table
|
|
in the @code{GDB} source directory.
|
|
|
|
@item m68k.c
|
|
All the mc680x0 code, in one huge, slow-to-compile file.
|
|
|
|
@item ns32k.c
|
|
This contains the code for the ns32032/ns32532 version of the
|
|
assembler.
|
|
|
|
@item ns32k-opcode.h
|
|
This contains the opcode table for the ns32032/ns32532 version
|
|
of the assembler.
|
|
|
|
@item vax-inst.h
|
|
Vax specific file for describing Vax operands and other Vax-ish things.
|
|
|
|
@item vax-opcode.h
|
|
Vax opcode table.
|
|
|
|
@item vax.c
|
|
Vax specific parts of @code{@value{AS}}. Also includes the former files
|
|
@file{vax-ins-parse.c}, @file{vax-reg-parse.c} and @file{vip-op.c}.
|
|
|
|
@item atof-vax.c
|
|
Turns a flonum into a Vax constant.
|
|
|
|
@item vms.c
|
|
This file contains the special code needed to put out a VMS
|
|
style object file for the Vax.
|
|
|
|
@end table
|
|
|
|
Here is a list of the header files in the source directory.
|
|
(Warning: This section may not be very accurate. I didn't
|
|
write the header files; I just report them.) Also note that I
|
|
think many of these header files could be cleaned up or
|
|
eliminated.
|
|
|
|
@table @file
|
|
|
|
@item a.out.h
|
|
This describes the structures used to create the binary header data
|
|
inside the object file. Perhaps we should use the one in
|
|
@file{/usr/include}?
|
|
|
|
@item as.h
|
|
This defines all the globally useful things, and pulls in @file{stdio.h}
|
|
and @file{assert.h}.
|
|
|
|
@item bignum.h
|
|
This defines macros useful for dealing with bignums.
|
|
|
|
@item expr.h
|
|
Structure and macros for dealing with expression()
|
|
|
|
@item flonum.h
|
|
This defines the structure for dealing with floating point
|
|
numbers. It #includes @file{bignum.h}.
|
|
|
|
@item frags.h
|
|
This contains macro for appending a byte to the current frag.
|
|
|
|
@item hash.h
|
|
Structures and function definitions for the hashing functions.
|
|
|
|
@item input-file.h
|
|
Function headers for the input-file.c functions.
|
|
|
|
@item md.h
|
|
structures and function headers for things defined in the
|
|
machine dependent part of the assembler.
|
|
|
|
@item obstack.h
|
|
This is the GNU systemwide include file for manipulating obstacks.
|
|
Since nobody is running under real GNU yet, we include this file.
|
|
|
|
@item read.h
|
|
Macros and function headers for reading in source files.
|
|
|
|
@item struct-symbol.h
|
|
Structure definition and macros for dealing with the @value{AS}
|
|
internal form of a symbol.
|
|
|
|
@item subsegs.h
|
|
structure definition for dealing with the numbered subsections
|
|
of the text and data sections.
|
|
|
|
@item symbols.h
|
|
Macros and function headers for dealing with symbols.
|
|
|
|
@item write.h
|
|
Structure for doing section fixups.
|
|
@end table
|
|
|
|
@c ~subsection Test Directory
|
|
@c (Note: The test directory seems to have disappeared somewhere
|
|
@c along the line. If you want it, you'll probably have to find a
|
|
@c REALLY OLD dump tape~dots{})
|
|
@c
|
|
@c The ~file{test/} directory is used for regression testing.
|
|
@c After you modify ~@code{@value{AS}}, you can get a quick go/nogo
|
|
@c confidence test by running the new ~@code{@value{AS}} over the source
|
|
@c files in this directory. You use a shell script ~file{test/do}.
|
|
@c
|
|
@c The tests in this suite are evolving. They are not comprehensive.
|
|
@c They have, however, caught hundreds of bugs early in the debugging
|
|
@c cycle of ~@code{@value{AS}}. Most test statements in this suite were naturally
|
|
@c selected: they were used to demonstrate actual ~@code{@value{AS}} bugs rather
|
|
@c than being written ~i{a prioi}.
|
|
@c
|
|
@c Another testing suggestion: over 30 bugs have been found simply by
|
|
@c running examples from this manual through ~@code{@value{AS}}.
|
|
@c Some examples in this manual are selected
|
|
@c to distinguish boundary conditions; they are good for testing ~@code{@value{AS}}.
|
|
@c
|
|
@c ~subsubsection Regression Testing
|
|
@c Each regression test involves assembling a file and comparing the
|
|
@c actual output of ~@code{@value{AS}} to ``known good'' output files. Both
|
|
@c the object file and the error/warning message file (stderr) are
|
|
@c inspected. Optionally the ~@code{@value{AS}} exit status may be checked.
|
|
@c Discrepencies are reported. Each discrepency means either that
|
|
@c you broke some part of ~@code{@value{AS}} or that the ``known good'' files
|
|
@c are now out of date and should be changed to reflect the new
|
|
@c definition of ``good''.
|
|
@c
|
|
@c Each regression test lives in its own directory, in a tree
|
|
@c rooted in the directory ~file{test/}. Each such directory
|
|
@c has a name ending in ~file{.ret}, where `ret' stands for
|
|
@c REgression Test. The ~file{.ret} ending allows ~code{find
|
|
@c (1)} to find all regression tests in the tree, without
|
|
@c needing to list them explicitly.
|
|
@c
|
|
@c Any ~file{.ret} directory must contain a file called
|
|
@c ~file{input} which is the source file to assemble. During
|
|
@c testing an object file ~file{output} is created, as well as
|
|
@c a file ~file{stdouterr} which contains the output to both
|
|
@c stderr and stderr. If there is a file ~file{output.good} in
|
|
@c the directory, and if ~file{output} contains exactly the
|
|
@c same data as ~file{output.good}, the file ~file{output} is
|
|
@c deleted. Likewise ~file{stdouterr} is removed if it exactly
|
|
@c matches a file ~file{stdouterr.good}. If file
|
|
@c ~file{status.good} is present, containing a decimal number
|
|
@c before a newline, the exit status of ~@code{@value{AS}} is compared
|
|
@c to this number. If the status numbers are not equal, a file
|
|
@c ~file{status} is written to the directory, containing the
|
|
@c actual status as a decimal number followed by newline.
|
|
@c
|
|
@c Should any of the ~file{*.good} files fail to match their corresponding
|
|
@c actual files, this is noted by a 1-line message on the screen during
|
|
@c the regression test, and you can use ~@code{find (1)} to find any
|
|
@c files named ~file{status}, ~file {output} or ~file{stdouterr}.
|
|
@c
|
|
|
|
@node Retargeting
|
|
@chapter Teaching the Assembler about a New Machine
|
|
|
|
This chapter describes the steps required in order to make the
|
|
assembler work with another machine's assembly language. This
|
|
chapter is not complete, and only describes the steps in the
|
|
broadest terms. You should look at the source for the
|
|
currently supported machine in order to discover some of the
|
|
details that aren't mentioned here.
|
|
|
|
You should create a new file called @file{@var{machine}.c}, and
|
|
add the appropriate lines to the file @file{Makefile} so that
|
|
you can compile your new version of the assembler. This should
|
|
be straighforward; simply add lines similar to the ones there
|
|
for the four current versions of the assembler.
|
|
|
|
If you want to be compatible with GDB, (and the current
|
|
machine-dependent versions of the assembler), you should create
|
|
a file called @file{@var{machine}-opcode.h} which should
|
|
contain all the information about the names of the machine
|
|
instructions, their opcodes, and what addressing modes they
|
|
support. If you do this right, the assembler and GDB can share
|
|
this file, and you'll only have to write it once. Note that
|
|
while you're writing @code{@value{AS}}, you may want to use an
|
|
independent program (if you have access to one), to make sure
|
|
that @code{@value{AS}} is emitting the correct bytes. Since @code{@value{AS}}
|
|
and @code{GDB} share the opcode table, an incorrect opcode
|
|
table entry may make invalid bytes look OK when you disassemble
|
|
them with @code{GDB}.
|
|
|
|
@section Functions You will Have to Write
|
|
|
|
Your file @file{@var{machine}.c} should contain definitions for
|
|
the following functions and variables. It will need to include
|
|
some header files in order to use some of the structures
|
|
defined in the machine-independent part of the assembler. The
|
|
needed header files are mentioned in the descriptions of the
|
|
functions that will need them.
|
|
|
|
@table @code
|
|
|
|
@item long omagic;
|
|
This long integer holds the value to place at the beginning of
|
|
the @file{a.out} file. It is usually @samp{OMAGIC}, except on
|
|
machines that store additional information in the magic-number.
|
|
|
|
@item char comment_chars[];
|
|
This character array holds the values of the characters that
|
|
start a comment anywhere in a line. Comments are stripped off
|
|
automatically by the machine independent part of the
|
|
assembler. Note that the @samp{/*} will always start a
|
|
comment, and that only @samp{*/} will end a comment started by
|
|
@samp{*/}.
|
|
|
|
@item char line_comment_chars[];
|
|
This character array holds the values of the chars that start a
|
|
comment only if they are the first (non-whitespace) character
|
|
on a line. If the character @samp{#} does not appear in this
|
|
list, you may get unexpected results. (Various
|
|
machine-independent parts of the assembler treat the comments
|
|
@samp{#APP} and @samp{#NO_APP} specially, and assume that lines
|
|
that start with @samp{#} are comments.)
|
|
|
|
@item char EXP_CHARS[];
|
|
This character array holds the letters that can separate the
|
|
mantissa and the exponent of a floating point number. Typical
|
|
values are @samp{e} and @samp{E}.
|
|
|
|
@item char FLT_CHARS[];
|
|
This character array holds the letters that--when they appear
|
|
immediately after a leading zero--indicate that a number is a
|
|
floating-point number. (Sort of how 0x indicates that a
|
|
hexadecimal number follows.)
|
|
|
|
@item pseudo_typeS md_pseudo_table[];
|
|
(@var{pseudo_typeS} is defined in @file{md.h})
|
|
This array contains a list of the machine_dependent directives
|
|
the assembler must support. It contains the name of each
|
|
pseudo op (Without the leading @samp{.}), a pointer to a
|
|
function to be called when that directive is encountered, and
|
|
an integer argument to be passed to that function.
|
|
|
|
@item void md_begin(void)
|
|
This function is called as part of the assembler's
|
|
initialization. It should do any initialization required by
|
|
any of your other routines.
|
|
|
|
@item int md_parse_option(char **optionPTR, int *argcPTR, char ***argvPTR)
|
|
This routine is called once for each option on the command line
|
|
that the machine-independent part of @code{@value{AS}} does not
|
|
understand. This function should return non-zero if the option
|
|
pointed to by @var{optionPTR} is a valid option. If it is not
|
|
a valid option, this routine should return zero. The variables
|
|
@var{argcPTR} and @var{argvPTR} are provided in case the option
|
|
requires a filename or something similar as an argument. If
|
|
the option is multi-character, @var{optionPTR} should be
|
|
advanced past the end of the option, otherwise every letter in
|
|
the option will be treated as a separate single-character
|
|
option.
|
|
|
|
@item void md_assemble(char *string)
|
|
This routine is called for every machine-dependent
|
|
non-directive line in the source file. It does all the real
|
|
work involved in reading the opcode, parsing the operands,
|
|
etc. @var{string} is a pointer to a null-terminated string,
|
|
that comprises the input line, with all excess whitespace and
|
|
comments removed.
|
|
|
|
@item void md_number_to_chars(char *outputPTR,long value,int nbytes)
|
|
This routine is called to turn a C long int, short int, or char
|
|
into the series of bytes that represents that number on the
|
|
target machine. @var{outputPTR} points to an array where the
|
|
result should be stored; @var{value} is the value to store; and
|
|
@var{nbytes} is the number of bytes in 'value' that should be
|
|
stored.
|
|
|
|
@item void md_number_to_imm(char *outputPTR,long value,int nbytes)
|
|
This routine is called to turn a C long int, short int, or char
|
|
into the series of bytes that represent an immediate value on
|
|
the target machine. It is identical to the function @code{md_number_to_chars},
|
|
except on NS32K machines.@refill
|
|
|
|
@item void md_number_to_disp(char *outputPTR,long value,int nbytes)
|
|
This routine is called to turn a C long int, short int, or char
|
|
into the series of bytes that represent an displacement value on
|
|
the target machine. It is identical to the function @code{md_number_to_chars},
|
|
except on NS32K machines.@refill
|
|
|
|
@item void md_number_to_field(char *outputPTR,long value,int nbytes)
|
|
This routine is identical to @code{md_number_to_chars},
|
|
except on NS32K machines.
|
|
|
|
@item void md_ri_to_chars(struct relocation_info *riPTR,ri)
|
|
(@code{struct relocation_info} is defined in @file{a.out.h})
|
|
This routine emits the relocation info in @var{ri}
|
|
in the appropriate bit-pattern for the target machine.
|
|
The result should be stored in the location pointed
|
|
to by @var{riPTR}. This routine may be a no-op unless you are
|
|
attempting to do cross-assembly.
|
|
|
|
@item char *md_atof(char type,char *outputPTR,int *sizePTR)
|
|
This routine turns a series of digits into the appropriate
|
|
internal representation for a floating-point number.
|
|
@var{type} is a character from @var{FLT_CHARS[]} that describes
|
|
what kind of floating point number is wanted; @var{outputPTR}
|
|
is a pointer to an array that the result should be stored in;
|
|
and @var{sizePTR} is a pointer to an integer where the size (in
|
|
bytes) of the result should be stored. This routine should
|
|
return an error message, or an empty string (not (char *)0) for
|
|
success.
|
|
|
|
@item int md_short_jump_size;
|
|
This variable holds the (maximum) size in bytes of a short (16
|
|
bit or so) jump created by @code{md_create_short_jump()}. This
|
|
variable is used as part of the broken-word feature, and isn't
|
|
needed if the assembler is compiled with
|
|
@samp{-DWORKING_DOT_WORD}.
|
|
|
|
@item int md_long_jump_size;
|
|
This variable holds the (maximum) size in bytes of a long (32
|
|
bit or so) jump created by @code{md_create_long_jump()}. This
|
|
variable is used as part of the broken-word feature, and isn't
|
|
needed if the assembler is compiled with
|
|
@samp{-DWORKING_DOT_WORD}.
|
|
|
|
@item void md_create_short_jump(char *resultPTR,long from_addr,
|
|
@code{long to_addr,fragS *frag,symbolS *to_symbol)}
|
|
This function emits a jump from @var{from_addr} to @var{to_addr} in
|
|
the array of bytes pointed to by @var{resultPTR}. If this creates a
|
|
type of jump that must be relocated, this function should call
|
|
@code{fix_new()} with @var{frag} and @var{to_symbol}. The jump
|
|
emitted by this function may be smaller than @var{md_short_jump_size},
|
|
but it must never create a larger one.
|
|
(If it creates a smaller jump, the extra bytes of memory will not be
|
|
used.) This function is used as part of the broken-word feature,
|
|
and isn't needed if the assembler is compiled with
|
|
@samp{-DWORKING_DOT_WORD}.@refill
|
|
|
|
@item void md_create_long_jump(char *ptr,long from_addr,
|
|
@code{long to_addr,fragS *frag,symbolS *to_symbol)}
|
|
This function is similar to the previous function,
|
|
@code{md_create_short_jump()}, except that it creates a long
|
|
jump instead of a short one. This function is used as part of
|
|
the broken-word feature, and isn't needed if the assembler is
|
|
compiled with @samp{-DWORKING_DOT_WORD}.
|
|
|
|
@item int md_estimate_size_before_relax(fragS *fragPTR,int segment_type)
|
|
This function does the initial setting up for relaxation. This
|
|
includes forcing references to still-undefined symbols to the
|
|
appropriate addressing modes.
|
|
|
|
@item relax_typeS md_relax_table[];
|
|
(relax_typeS is defined in md.h)
|
|
This array describes the various machine dependent states a
|
|
frag may be in before relaxation. You will need one group of
|
|
entries for each type of addressing mode you intend to relax.
|
|
|
|
@item void md_convert_frag(fragS *fragPTR)
|
|
(@var{fragS} is defined in @file{as.h})
|
|
This routine does the required cleanup after relaxation.
|
|
Relaxation has changed the type of the frag to a type that can
|
|
reach its destination. This function should adjust the opcode
|
|
of the frag to use the appropriate addressing mode.
|
|
@var{fragPTR} points to the frag to clean up.
|
|
|
|
@item void md_end(void)
|
|
This function is called just before the assembler exits. It
|
|
need not free up memory unless the operating system doesn't do
|
|
it automatically on exit. (In which case you'll also have to
|
|
track down all the other places where the assembler allocates
|
|
space but never frees it.)
|
|
|
|
@end table
|
|
|
|
@section External Variables You will Need to Use
|
|
|
|
You will need to refer to or change the following external variables
|
|
from within the machine-dependent part of the assembler.
|
|
|
|
@table @code
|
|
@item extern char flagseen[];
|
|
This array holds non-zero values in locations corresponding to
|
|
the options that were on the command line. Thus, if the
|
|
assembler was called with @samp{-W}, @var{flagseen['W']} would
|
|
be non-zero.
|
|
|
|
@item extern fragS *frag_now;
|
|
This pointer points to the current frag--the frag that bytes
|
|
are currently being added to. If nothing else, you will need
|
|
to pass it as an argument to various machine-independent
|
|
functions. It is maintained automatically by the
|
|
frag-manipulating functions; you should never have to change it
|
|
yourself.
|
|
|
|
@item extern LITTLENUM_TYPE generic_bignum[];
|
|
(@var{LITTLENUM_TYPE} is defined in @file{bignum.h}.
|
|
This is where @dfn{bignums}--numbers larger than 32 bits--are
|
|
returned when they are encountered in an expression. You will
|
|
need to use this if you need to implement directives (or
|
|
anything else) that must deal with these large numbers.
|
|
@code{Bignums} are of @code{segT} @code{SEG_BIG} (defined in
|
|
@file{as.h}, and have a positive @code{X_add_number}. The
|
|
@code{X_add_number} of a @code{bignum} is the number of
|
|
@code{LITTLENUMS} in @var{generic_bignum} that the number takes
|
|
up.
|
|
|
|
@item extern FLONUM_TYPE generic_floating_point_number;
|
|
(@var{FLONUM_TYPE} is defined in @file{flonum.h}.
|
|
The is where @dfn{flonums}--floating-point numbers within
|
|
expressions--are returned. @code{Flonums} are of @code{segT}
|
|
@code{SEG_BIG}, and have a negative @code{X_add_number}.
|
|
@code{Flonums} are returned in a generic format. You will have
|
|
to write a routine to turn this generic format into the
|
|
appropriate floating-point format for your machine.
|
|
|
|
@item extern int need_pass_2;
|
|
If this variable is non-zero, the assembler has encountered an
|
|
expression that cannot be assembled in a single pass. Since
|
|
the second pass isn't implemented, this flag means that the
|
|
assembler is punting, and is only looking for additional syntax
|
|
errors. (Or something like that.)
|
|
|
|
@item extern segT now_seg;
|
|
This variable holds the value of the section the assembler is
|
|
currently assembling into.
|
|
|
|
@end table
|
|
|
|
@section External functions will you need
|
|
|
|
You will find the following external functions useful (or
|
|
indispensable) when you're writing the machine-dependent part
|
|
of the assembler.
|
|
|
|
@table @code
|
|
|
|
@item char *frag_more(int bytes)
|
|
This function allocates @var{bytes} more bytes in the current
|
|
frag (or starts a new frag, if it can't expand the current frag
|
|
any more.) for you to store some object-file bytes in. It
|
|
returns a pointer to the bytes, ready for you to store data in.
|
|
|
|
@item void fix_new(fragS *frag, int where, short size, symbolS *add_symbol, symbolS *sub_symbol, long offset, int pcrel)
|
|
This function stores a relocation fixup to be acted on later.
|
|
@var{frag} points to the frag the relocation belongs in;
|
|
@var{where} is the location within the frag where the relocation begins;
|
|
@var{size} is the size of the relocation, and is usually 1 (a single byte),
|
|
2 (sixteen bits), or 4 (a longword). The value @var{add_symbol}
|
|
@minus{} @var{sub_symbol} + @var{offset}, is added to the byte(s) at
|
|
@var{frag->literal[where]}. If @var{pcrel} is non-zero, the address of
|
|
the location is subtracted from the result. A relocation entry is also
|
|
added to the @file{a.out} file. @var{add_symbol}, @var{sub_symbol},
|
|
and/or @var{offset} may be NULL.@refill
|
|
|
|
@item char *frag_var(relax_stateT type, int max_chars, int var,
|
|
@code{relax_substateT subtype, symbolS *symbol, char *opcode)}
|
|
This function creates a machine-dependent frag of type @var{type}
|
|
(usually @code{rs_machine_dependent}).
|
|
@var{max_chars} is the maximum size in bytes that the frag may grow by;
|
|
@var{var} is the current size of the variable end of the frag;
|
|
@var{subtype} is the sub-type of the frag. The sub-type is used to index into
|
|
@var{md_relax_table[]} during @code{relaxation}.
|
|
@var{symbol} is the symbol whose value should be used to when relax-ing this frag.
|
|
@var{opcode} points into a byte whose value may have to be modified if the
|
|
addressing mode used by this frag changes. It typically points into the
|
|
@var{fr_literal[]} of the previous frag, and is used to point to a location
|
|
that @code{md_convert_frag()}, may have to change.@refill
|
|
|
|
@item void frag_wane(fragS *fragPTR)
|
|
This function is useful from within @code{md_convert_frag}. It
|
|
changes a frag to type rs_fill, and sets the variable-sized
|
|
piece of the frag to zero. The frag will never change in size
|
|
again.
|
|
|
|
@item segT expression(expressionS *retval)
|
|
(@var{segT} is defined in @file{as.h}; @var{expressionS} is defined in @file{expr.h})
|
|
This function parses the string pointed to by the external char
|
|
pointer @var{input_line_pointer}, and returns the section-type
|
|
of the expression. It also stores the results in the
|
|
@var{expressionS} pointed to by @var{retval}.
|
|
@var{input_line_pointer} is advanced to point past the end of
|
|
the expression. (@var{input_line_pointer} is used by other
|
|
parts of the assembler. If you modify it, be sure to restore
|
|
it to its original value.)
|
|
|
|
@item as_warn(char *message,@dots{})
|
|
If warning messages are disabled, this function does nothing.
|
|
Otherwise, it prints out the current file name, and the current
|
|
line number, then uses @code{fprintf} to print the
|
|
@var{message} and any arguments it was passed.
|
|
|
|
@item as_bad(char *message,@dots{})
|
|
This function should be called when @code{@value{AS}} encounters
|
|
conditions that are bad enough that @code{@value{AS}} should not
|
|
produce an object file, but should continue reading input and
|
|
printing warning and bad error messages.
|
|
|
|
@item as_fatal(char *message,@dots{})
|
|
This function prints out the current file name and line number,
|
|
prints the word @samp{FATAL:}, then uses @code{fprintf} to
|
|
print the @var{message} and any arguments it was passed. Then
|
|
the assembler exits. This function should only be used for
|
|
serious, unrecoverable errors.
|
|
|
|
@item void float_const(int float_type)
|
|
This function reads floating-point constants from the current
|
|
input line, and calls @code{md_atof} to assemble them. It is
|
|
useful as the function to call for the directives
|
|
@samp{.single}, @samp{.double}, @samp{.float}, etc.
|
|
@var{float_type} must be a character from @var{FLT_CHARS}.
|
|
|
|
@item void demand_empty_rest_of_line(void);
|
|
This function can be used by machine-dependent directives to
|
|
make sure the rest of the input line is empty. It prints a
|
|
warning message if there are additional characters on the line.
|
|
|
|
@item long int get_absolute_expression(void)
|
|
This function can be used by machine-dependent directives to
|
|
read an absolute number from the current input line. It
|
|
returns the result. If it isn't given an absolute expression,
|
|
it prints a warning message and returns zero.
|
|
|
|
@end table
|
|
|
|
|
|
@section The concept of Frags
|
|
|
|
This assembler works to optimize the size of certain addressing
|
|
modes. (e.g. branch instructions) This means the size of many
|
|
pieces of object code cannot be determined until after assembly
|
|
is finished. (This means that the addresses of symbols cannot be
|
|
determined until assembly is finished.) In order to do this,
|
|
@code{@value{AS}} stores the output bytes as @dfn{frags}.
|
|
|
|
Here is the definition of a frag (from @file{as.h})
|
|
@smallexample
|
|
struct frag
|
|
@{
|
|
long int fr_fix;
|
|
long int fr_var;
|
|
relax_stateT fr_type;
|
|
relax_substateT fr_substate;
|
|
unsigned long fr_address;
|
|
long int fr_offset;
|
|
struct symbol *fr_symbol;
|
|
char *fr_opcode;
|
|
struct frag *fr_next;
|
|
char fr_literal[];
|
|
@}
|
|
@end smallexample
|
|
|
|
@table @var
|
|
@item fr_fix
|
|
is the size of the fixed-size piece of the frag.
|
|
|
|
@item fr_var
|
|
is the maximum (?) size of the variable-sized piece of the frag.
|
|
|
|
@item fr_type
|
|
is the type of the frag.
|
|
Current types are:
|
|
rs_fill
|
|
rs_align
|
|
rs_org
|
|
rs_machine_dependent
|
|
|
|
@item fr_substate
|
|
This stores the type of machine-dependent frag this is. (what
|
|
kind of addressing mode is being used, and what size is being
|
|
tried/will fit/etc.
|
|
|
|
@item fr_address
|
|
@var{fr_address} is only valid after relaxation is finished.
|
|
Before relaxation, the only way to store an address is (pointer
|
|
to frag containing the address) plus (offset into the frag).
|
|
|
|
@item fr_offset
|
|
This contains a number, whose meaning depends on the type of
|
|
the frag.
|
|
for machine_dependent frags, this contains the offset from
|
|
fr_symbol that the frag wants to go to. Thus, for branch
|
|
instructions it is usually zero. (unless the instruction was
|
|
@samp{jba foo+12} or something like that.)
|
|
|
|
@item fr_symbol
|
|
for machine_dependent frags, this points to the symbol the frag
|
|
needs to reach.
|
|
|
|
@item fr_opcode
|
|
This points to the location in the frag (or in a previous frag)
|
|
of the opcode for the instruction that caused this to be a frag.
|
|
@var{fr_opcode} is needed if the actual opcode must be changed
|
|
in order to use a different form of the addressing mode.
|
|
(For example, if a conditional branch only comes in size tiny,
|
|
a large-size branch could be implemented by reversing the sense
|
|
of the test, and turning it into a tiny branch over a large jump.
|
|
This would require changing the opcode.)
|
|
|
|
@var{fr_literal} is a variable-size array that contains the
|
|
actual object bytes. A frag consists of a fixed size piece of
|
|
object data, (which may be zero bytes long), followed by a
|
|
piece of object data whose size may not have been determined
|
|
yet. Other information includes the type of the frag (which
|
|
controls how it is relaxed),
|
|
|
|
@item fr_next
|
|
This is the next frag in the singly-linked list. This is
|
|
usually only needed by the machine-independent part of
|
|
@code{@value{AS}}.
|
|
|
|
@end table
|
|
@end ignore
|
|
|
|
@ifset GENERIC
|
|
@include gpl.texinfo
|
|
@end ifset
|
|
|
|
@node Index
|
|
@unnumbered Index
|
|
|
|
@printindex cp
|
|
|
|
@contents
|
|
@bye
|