mirror of
https://github.com/netwide-assembler/nasm.git
synced 2024-12-03 08:41:02 +08:00
124a462cc2
Signed-off-by: Cyrill Gorcunov <gorcunov@gmail.com>
536 lines
12 KiB
Groff
536 lines
12 KiB
Groff
.TH NASM 1 "The Netwide Assembler Project"
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.SH NAME
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nasm \- the Netwide Assembler, a portable 80x86 assembler
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.SH SYNOPSIS
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.B nasm
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[
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.B \-@
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response file
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] [
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.B \-f
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format
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] [
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.B \-o
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outfile
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] [
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.B \-l
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listfile
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] [
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.IR options ...
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] filename
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.br
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.B nasm \-h
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.br
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.B nasm \-v
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.SH DESCRIPTION
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The
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.B nasm
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command assembles the file
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.I filename
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and directs output to the file
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.I outfile
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if specified. If
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.I outfile
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is not specified,
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.B nasm
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will derive a default output file name from the name of its input
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file, usually by appending `.o' or `.obj', or by removing all
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extensions for a raw binary file. Failing that, the output file name
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will be `nasm.out'.
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.SS OPTIONS
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.TP
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.BI \-@ " filename"
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Causes
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.B nasm
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to process options from
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.I filename
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as if they were included on the command line.
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.TP
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.B \-a
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Causes
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.B nasm
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to assemble the given input file without first applying the macro
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preprocessor.
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.TP
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.BI \-D " macro[=value]"
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Pre-defines a single-line macro.
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.TP
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.BI \-d " macro[=value]"
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Same as the
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.B \-D
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option.
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.TP
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.B \-e
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Causes
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.B nasm
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to preprocess the given input file, and write the output to
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.I stdout
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(or the specified output file name), and not actually assemble
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anything.
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.TP
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.BI \-f " format"
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Specifies the output file format. To see a list of valid output
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formats, use the
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.B -hf
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option.
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.TP
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.B \-g
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Causes
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.B nasm
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to generate debug information in selected format
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.TP
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.B \-h
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Causes
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.B nasm
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to exit immediately, after giving a summary of its invocation
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options.
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.TP
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.B \-hf
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Same as
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.B -h
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, but also lists all valid output formats.
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.TP
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.BI \-I " directory"
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Adds a directory to the search path for include files. The directory
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specification must include the trailing slash, as it will be
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directly prepended to the name of the include file.
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.TP
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.BI \-i " directory"
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Same as the
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.B \-I
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option.
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.TP
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.BI \-l " listfile"
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Causes an assembly listing to be directed to the given file, in
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which the original source is displayed on the right hand side (plus
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the source for included files and the expansions of multi-line
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macros) and the generated code is shown in hex on the left.
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.TP
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.B \-M
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Causes
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.B nasm
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to output Makefile-style dependencies to stdout; normal output is
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suppressed.
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.TP
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.BI \-MG " file"
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Same as
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.B \-M
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but assumes that missing Makefile dependecies are generated and added
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to dependency list without a prefix.
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.TP
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.BI \-MF " file"
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Output Makefile-style dependencies to the specified file.
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.TP
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.BI \-MD " file"
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Same as a combination of
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.B \-M
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and
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.B \-MF
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options.
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.TP
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.BI \-MT " file"
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Override the default name of the dependency target
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dependency target name. This is normally the same
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as the output filename, specified by the
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.B \-o
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option.
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.TP
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.BI \-MQ " file"
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The same as
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.B \-MT
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except it tries to quote characters that have special
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meaning in Makefile syntax. This is not foolproof,
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as not all characters with special meaning are quotable
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in Make.
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.TP
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.BI \-MP
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Emit phony target
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.TP
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.BI \-O " number"
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Optimize branch offsets.
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.ti
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.B \-O0
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:No optimization (default)
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.ti
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.B \-O1
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:Minimal optimization
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.ti
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.B \-Ox
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:Multipass optimization (recommended)
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.TP
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.BI \-o " outfile"
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Specifies a precise name for the output file, overriding
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.BR nasm 's
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default means of determining it.
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.TP
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.BI \-P " file"
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Specifies a file to be pre-included, before the main source file
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starts to be processed.
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.TP
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.BI \-p " file"
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Same as the
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.B \-P
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option.
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.TP
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.BI \-r
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Causes
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.B nasm
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to exit immediately, after displaying its version number.
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.I (obsolete)
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.TP
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.B \-s
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Causes
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.B nasm
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to send its error messages and/or help text to
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.I stdout
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instead of
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.IR stderr .
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.TP
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.B \-t
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Causes
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.B nasm
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to assemble in SciTech TASM compatible mode
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.TP
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.BI \-U " macro"
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Undefines a single-line macro.
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.TP
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.BI \-u " macro"
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Same as the
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.B \-U
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option.
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.TP
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.BI \-v
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Causes
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.B nasm
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to exit immediately, after displaying its version number.
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.TP
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.BI \-w [+-]foo
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Causes
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.B nasm
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to enable or disable certain classes of warning messages, for
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example
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.B \-w+orphan-labels
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or
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.B \-w-macro-params
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.TP
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.BI \-X " format"
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specifies error reporting format (gnu or vc).
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.TP
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.BI \-Z " filename"
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Causes
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.B nasm
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to redirect error messages to
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.IR filename .
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This option exists to support operating systems on which stderr is not
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easily redirected.
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.TP
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.BI \-\-prefix
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.TP
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.BI \-\-postfix
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Prepend or append (respectively) the given argument to all
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global or extern variables.
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.PP
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.RE
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.SS SYNTAX
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This man page does not fully describe the syntax of
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.BR nasm 's
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assembly language, but does give a summary of the differences from
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other assemblers.
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.PP
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.I Registers
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have no leading `%' sign, unlike
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.BR gas ,
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and floating-point stack registers are referred to as
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.IR st0 ,
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.IR st1 ,
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and so on.
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.PP
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.I Floating-point instructions
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may use either the single-operand form or the double. A
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.I TO
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keyword is provided; thus, one could either write
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.PP
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.ti +15n
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fadd st0,st1
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.br
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.ti +15n
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fadd st1,st0
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.PP
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or one could use the alternative single-operand forms
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.PP
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.ti +15n
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fadd st1
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.br
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.ti +15n
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fadd to st1
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.PP
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.I Uninitialised storage
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is reserved using the
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.IR RESB ,
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.IR RESW ,
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.IR RESD ,
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.IR RESQ ,
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.I REST
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and
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.I RESO
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pseudo-opcodes, each taking one parameter which gives the number of
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bytes, words, doublewords, quadwords or ten-byte words to reserve.
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.PP
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.I Repetition
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of data items is not done by the
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.I DUP
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keyword as seen in DOS assemblers, but by the use of the
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.I TIMES
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prefix, like this:
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.PP
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.ti +6n
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.ta 9n
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message: times 3 db 'abc'
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.br
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.ti +15n
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times 64-$+message db 0
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.PP
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which defines the string `abcabcabc', followed by the right number
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of zero bytes to make the total length up to 64 bytes.
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.PP
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.I Symbol references
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are always understood to be immediate (i.e. the address of the
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symbol), unless square brackets are used, in which case the contents
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of the memory location are used. Thus:
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.PP
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.ti +15n
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mov ax,wordvar
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.PP
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loads AX with the address of the variable `wordvar', whereas
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.PP
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.ti +15n
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mov ax,[wordvar]
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.br
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.ti +15n
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mov ax,[wordvar+1]
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.br
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.ti +15n
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mov ax,[es:wordvar+bx]
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.PP
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all refer to the
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.I contents
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of memory locations. The syntaxes
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.PP
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.ti +15n
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mov ax,es:wordvar[bx]
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.br
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.ti +15n
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es mov ax,wordvar[1]
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.PP
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are not legal at all, although the use of a segment register name as
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an instruction prefix is valid, and can be used with instructions
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such as
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.I LODSB
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which can't be overridden any other way.
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.PP
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.I Constants
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may be expressed numerically in most formats: a trailing H, Q or B
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denotes hex, octal or binary respectively, and a leading `0x' or `$'
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denotes hex as well. Leading zeros are not treated specially at all.
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Character constants may be enclosed in single or double quotes;
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there is no escape character. The ordering is little-endian
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(reversed), so that the character constant
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.I 'abcd'
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denotes 0x64636261 and not 0x61626364.
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.PP
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.I Local labels
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begin with a period, and their `locality' is granted by the
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assembler prepending the name of the previous non-local symbol. Thus
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declaring a label `.loop' after a label `label' has actually defined
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a symbol called `label.loop'.
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.SS DIRECTIVES
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.I SECTION name
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or
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.I SEGMENT name
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causes
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.B nasm
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to direct all following code to the named section. Section names
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vary with output file format, although most formats support the
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names
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.IR .text ,
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.I .data
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and
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.IR .bss .
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(The exception is the
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.I obj
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format, in which all segments are user-definable.)
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.PP
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.I ABSOLUTE address
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causes
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.B nasm
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to position its notional assembly point at an absolute address: so
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no code or data may be generated, but you can use
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.IR RESB ,
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.I RESW
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and
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.I RESD
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to move the assembly point further on, and you can define labels. So
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this directive may be used to define data structures. When you have
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finished doing absolute assembly, you must issue another
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.I SECTION
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directive to return to normal assembly.
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.PP
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.I BITS 16,
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.I BITS 32
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or
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.I BITS 64
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switches the default processor mode for which
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.B nasm
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is generating code: it is equivalent to
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.I USE16
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or
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.I USE32
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in DOS assemblers.
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.PP
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.I EXTERN symbol
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and
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.I GLOBAL symbol
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import and export symbol definitions, respectively, from and to
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other modules. Note that the
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.I GLOBAL
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directive must appear before the definition of the symbol it refers
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to.
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.PP
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.I STRUC strucname
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and
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.IR ENDSTRUC ,
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when used to bracket a number of
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.IR RESB ,
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.I RESW
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or similar instructions, define a data structure. In addition to
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defining the offsets of the structure members, the construct also
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defines a symbol for the size of the structure, which is simply the
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structure name with
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.I _size
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tacked on to the end.
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.SS FORMAT-SPECIFIC DIRECTIVES
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.I ORG address
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is used by the
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.I bin
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flat-form binary output format, and specifies the address at which
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the output code will eventually be loaded.
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.PP
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.I GROUP grpname seg1 seg2...
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is used by the
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.I obj
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(Microsoft 16-bit) output format, and defines segment groups. This
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format also uses
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.IR UPPERCASE ,
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which directs that all segment, group and symbol names output to the
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object file should be in uppercase. Note that the actual assembly is
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still case sensitive.
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.PP
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.I LIBRARY libname
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is used by the
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.I rdf
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output format, and causes a dependency record to be written to the
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output file which indicates that the program requires a certain
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library in order to run.
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.SS MACRO PREPROCESSOR
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Single-line macros are defined using the
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.I %define
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or
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.I %idefine
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commands, in a similar fashion to the C preprocessor. They can be
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overloaded with respect to number of parameters, although defining a
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macro with no parameters prevents the definition of any macro with
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the same name taking parameters, and vice versa.
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.I %define
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defines macros whose names match case-sensitively, whereas
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.I %idefine
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defines case-insensitive macros.
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.PP
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Multi-line macros are defined using
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.I %macro
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and
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.I %imacro
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(the distinction is the same as that between
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.I %define
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and
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.IR %idefine ),
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whose syntax is as follows:
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.PP
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.ti +6n
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%macro
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.I name
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.IR minprm [- maxprm "][+][.nolist] [" defaults ]
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.br
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.ti +15n
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<some lines of macro expansion text>
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.br
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.ti +6n
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%endmacro
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.PP
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Again, these macros may be overloaded. The trailing plus sign
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indicates that any parameters after the last one get subsumed, with
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their separating commas, into the last parameter. The
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.I defaults
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part can be used to specify defaults for unspecified macro
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parameters after
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.IR minparam .
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.I %endm
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is a valid synonym for
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.IR %endmacro .
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.PP
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To refer to the macro parameters within a macro expansion, you use
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.IR %1 ,
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.I %2
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and so on. You can also enforce that a macro parameter should
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contain a condition code by using
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.IR %+1 ,
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and you can invert the condition code by using
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.IR %-1 .
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You can also define a label specific to a macro invocation by
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prefixing it with a double % sign.
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.PP
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Files can be included using the
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.I %include
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directive, which works like C.
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.PP
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The preprocessor has a `context stack', which may be used by one
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macro to store information that a later one will retrieve. You can
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push a context on the stack using
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.IR %push ,
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remove one using
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.IR %pop ,
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and change the name of the top context (without disturbing any
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associated definitions) using
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.IR %repl .
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Labels and
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.I %define
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macros specific to the top context may be defined by prefixing their
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names with %$, and things specific to the next context down with
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%$$, and so on.
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.PP
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Conditional assembly is done by means of
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.IR %ifdef ,
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.IR %ifndef ,
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.I %else
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and
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.I %endif
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as in C. (Except that
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.I %ifdef
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can accept several putative macro names, and will evaluate TRUE if
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any of them is defined.) In addition, the directives
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.I %ifctx
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and
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.I %ifnctx
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can be used to condition on the name of the top context on the
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context stack. The obvious set of `else-if' directives,
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.IR %elifdef ,
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.IR %elifndef ,
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.IR %elifctx
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and
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.IR %elifnctx
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are also supported.
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.SH BUGS
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Please report bugs through the bug tracker function at http://nasm.sourceforge.org.
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.SH SEE ALSO
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.BR as "(" 1 "),"
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.BR ld "(" 1 ")."
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