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nasmdoc: document %substr, ...

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H. Peter Anvin 2008-06-01 22:35:47 -07:00
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1 changed files with 46 additions and 14 deletions
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doc/nasmdoc.src
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@ -1445,10 +1445,12 @@ Some examples:
\S{chrconst} \i{Character Constants}
A character constant consists of up to four characters enclosed in
either single or double quotes. The type of quote makes no
difference to NASM, except of course that surrounding the constant
with single quotes allows double quotes to appear within it and vice
versa.
either single quotes (\c{'...'}), double quotes (\c{"..."}) or
backquotes (\c{`...`}). Single or double quotes are equivalent to
NASM (except of course that surrounding the constant with single
quotes allows double quotes to appear within it and vice versa); the
contents of those are represented verbatim. Strings enclosed in
backquotes support C-style \c{\\}-escapes for special characters.
A character constant with more than one character will be arranged
with \i{little-endian} order in mind: if you code
@ -1462,6 +1464,31 @@ the sense of character constants understood by the Pentium's
\i\c{CPUID} instruction.
\# (see \k{insCPUID})
The following escape sequences are recognized by backquoted strings:
\c \' single quote (')
\c \" double quote (")
\c \` backquote (`)
\c \\\ backslash (\)
\c \? question mark (?)
\c \a BEL (ASCII 7)
\c \b BS (ASCII 8)
\c \n LF (ASCII 10)
\c \v VT (ASCII 11)
\c \f FF (ASCII 12)
\c \r CR (ASCII 13)
\c \e ESC (ASCII 27)
\c \377 Up to 3 octal digits - ASCII literal
\c \xFF Up to 2 hexadecimal digits - ASCII literal
\c \u1234 4 hexadecimal digits - Unicode character
\c \U12345678 8 hexadecimal digits - Unicode character
All other escape sequences are reserved. Note that \c{\\0}, meaning a
\c{NUL} character, is a special case of the octal escape sequence.
Unicode characters specified with \c{\\u} or \c{\\U} are converted to
UTF-8.
\S{strconst} String Constants
@ -2165,17 +2192,22 @@ assigned the value of 9.
Individual letters in strings can be extracted using \c{%substr}.
An example of its use is probably more useful than the description:
\c %substr mychar 'xyz' 1 ; equivalent to %define mychar 'x'
\c %substr mychar 'xyz' 2 ; equivalent to %define mychar 'y'
\c %substr mychar 'xyz' 3 ; equivalent to %define mychar 'z'
\c %substr mychar 'xyzw' 1 ; equivalent to %define mychar 'x'
\c %substr mychar 'xyzw' 2 ; equivalent to %define mychar 'y'
\c %substr mychar 'xyzw' 3 ; equivalent to %define mychar 'z'
\c %substr mychar 'xyzw' 2,2 ; equivalent to %define mychar 'yz'
\c %substr mychar 'xyzw' 2,-1 ; equivalent to %define mychar 'yzw'
\c %substr mychar 'xyzw' 2,-2 ; equivalent to %define mychar 'yz'
In this example, mychar gets the value of 'y'. As with \c{%strlen}
(see \k{strlen}), the first parameter is the single-line macro to
be created and the second is the string. The third parameter
specifies which character is to be selected. Note that the first
index is 1, not 0 and the last index is equal to the value that
\c{%strlen} would assign given the same string. Index values out
of range result in an empty string.
As with \c{%strlen} (see \k{strlen}), the first parameter is the
single-line macro to be created and the second is the string. The
third parameter specifies the first character to be selected, and the
optional fourth parameter preceeded by comma) is the length. Note
that the first index is 1, not 0 and the last index is equal to the
value that \c{%strlen} would assign given the same string. Index
values out of range result in an empty string. A negative length
means "until N-1 characters before the end of string", i.e. \c{-1}
means until end of string, \c{-2} until one character before, etc.
\H{mlmacro} \i{Multi-Line Macros}: \I\c{%imacro}\i\c{%macro}