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Correct info about evaluating macro args (distinct from evaluating preprocessor

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vars); add version number (1); formatting improvements.
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Roland Pesch 1994-02-18 01:10:24 +00:00
parent 8981cac563
commit 673b162c1a
1 changed files with 28 additions and 18 deletions
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46
gas/doc/gasp.texi
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@ -12,7 +12,7 @@
@ifinfo
@format
START-INFO-DIR-ENTRY
* gasp:(gasp). The GNU Assembler Preprocessor
* gasp: (gasp). The GNU Assembler Preprocessor
END-INFO-DIR-ENTRY
@end format
@end ifinfo
@ -24,9 +24,10 @@ END-INFO-DIR-ENTRY
@settitle GASP
@titlepage
@c FIXME boring title
@title DRAFT EDITION
@sp 4
@title GASP, an assembly preprocessor
@c FIXME! Get a version number, global-replace '??'
@subtitle for GASP version ??
@subtitle for GASP version 1
@sp 1
@subtitle January 1994
@author Roland Pesch
@ -80,7 +81,7 @@ into another language, under the above conditions for modified versions.
GASP is a preprocessor for assembly programs.
This file describes version ?? of GASP.
This file describes version 1 of GASP.
Steve Chamberlain wrote GASP; Roland Pesch wrote this manual.
@ -371,7 +372,6 @@ You can use variables in @sc{gasp} to represent strings, registers, or
the results of expressions.
You must distinguish two kinds of variables:
@c FIXME! Is this crud true about conditional comparisons vs variables?
@enumerate
@item
Variables defined with @code{.EQU} or @code{.ASSIGN}. To evaluate this
@ -391,8 +391,8 @@ while loops; @sc{gasp} only evaluates these variables when writing
assembly output.
@item
Variables for use during preprocessing. These are defined as macro
arguments, or with @code{.ASSIGNC} or @code{.ASSIGNA}. To evaluate this
Variables for use during preprocessing. You can define these
with @code{.ASSIGNC} or @code{.ASSIGNA}. To evaluate this
kind of variable, write @samp{\&} before the variable name; for example,
@cartouche
@ -404,6 +404,10 @@ opcit .ASSIGNA 47
.AENDW
@end example
@end cartouche
@sc{gasp} treats macro arguments almost the same way, but to evaluate
them you use the prefix @samp{\} rather than @samp{\&}.
@xref{Macros,, Defining your own directives}.
@end enumerate
@ftable @code
@ -439,11 +443,13 @@ that is at the left margin. You may specify a colon after the variable
name if you wish; the first example above could have started @samp{eg:}
with the same effect.
@c pagebreak makes for better aesthetics---ensures macro and expansion together
@page
@node Macros
@section Defining your own directives
The commands @code{.MACRO} and @code{.ENDM} allow you to define macros
that generate assembly output, and that you can use with a syntax
that generate assembly output. You can use these macros with a syntax
similar to built-in @sc{gasp} or assembler directives. For example,
this definition specifies a macro @code{SUM} that adds together a range of
consecutive registers:
@ -494,23 +500,27 @@ arguments.
@item .MACRO PLUS1 P, P1
@itemx .MACRO PLUS1 P P1
Either statement begins the definition of a macro called @code{PLUS1},
which takes two arguments; within the macro definition, these arguments
are evaluated as @samp{\&P} and @samp{\&P1}.
which takes two arguments; within the macro definition, write
@samp{\P} or @samp{\P1} to evaluate the arguments.
@item .MACRO RESERVE_STR P1=0 P2
Begin the definition of a macro called @code{RESERVE_STR}, with two
arguments. The first argument has a default value, but not the second.
After the definition is complete, you can call the macro either as
@samp{RESERVE_STR @var{a},@var{b}} (with @samp{\&P1} evaluating to
@var{a} and @samp{\&P2} evaluating to @var{b}), or as @samp{RESERVE_STR
,@var{b}} (with @samp{\&P1} evaluating as the default, in this case
@samp{0}, and @samp{\&P2} evaluating to @var{b}).
@samp{RESERVE_STR @var{a},@var{b}} (with @samp{\P1} evaluating to
@var{a} and @samp{\P2} evaluating to @var{b}), or as @samp{RESERVE_STR
,@var{b}} (with @samp{\P1} evaluating as the default, in this case
@samp{0}, and @samp{\P2} evaluating to @var{b}).
@end table
When you call a macro, the values are assigned by position to each
argument name. Macro arguments are preprocessor variables in the same
way as variables you define with @samp{.ASSIGNA} or @samp{.ASSIGNC}, and
you can therefore use them in conditionals or for loop control.
When you call a macro, you can specify the argument values either by
position, or by keyword. For example, @samp{SUM 9,17} is equivalent to
@samp{SUM TO=17, FROM=9}. Macro arguments are preprocessor variables
similar to the variables you define with @samp{.ASSIGNA} or
@samp{.ASSIGNC}; in particular, you can use them in conditionals or for
loop control. (The only difference is the prefix you write to evaluate
the variable: for a macro argument, write @samp{\@var{argname}}, but for
a preprocessor variable, write @samp{\&@var{varname}}.)
@item @var{name} .MACRO
@itemx @var{name} .MACRO ( @var{macargs} @dots{} )