The primary purpose of the GNU assembler is to assemble the output of
other programs--notably compilers. When you have to hand-code
specialized routines in assembly, that means the GNU assembler is an
unfriendly processor: it has no directives for macros, conditionals, or
many other conveniences that you might expect.
In some cases you can simply use the C preprocessor, or a generalized
preprocessor like M4; but this can be awkward, since none of these
things are designed with assembly in mind.
gasp fills this need. It is expressly designed to provide the
facilities you need with hand-coded assembly code. Implementing it as a
preprocessor, rather than part of the assembler, allows the maximum
flexibility: you can use it with hand-coded assembly, without paying a
penalty of added complexity in the assembler you use for compiler
are the files to be preprocessed.
The simplest way to use GASP is to run it as a filter and assemble
its output. In Unix and its ilk, you can do this, for example:
$ gasp prog.asm | as -o prog.o
Naturally, there are also a few command-line options to allow you to
request variations on this basic theme. Here is the full set of
possibilities for the GASP command line.
Use alternative macro syntax. *Note Alternate macro syntax:
Alternate, for a discussion of how this syntax differs from the
default GASP syntax.
Use CHAR as the comment character. The default comment character
is `!'. For example, to use a semicolon as the comment character,
specify `-c ';'' on the GASP command line. Since assembler
command characters often have special significance to command
shells, it is a good idea to quote or escape CHAR when you specify
a comment character.
For the sake of simplicity, all examples in this manual use the
default comment character `!'.
Show debugging statistics. In this version of GASP, this option
produces statistics about the string buffers that GASP allocates
internally. For each defined buffersize S, GASP shows the number
of strings N that it allocated, with a line like this:
strings size S : N
GASP displays these statistics on the standard error stream, when
Display a summary of the GASP command line options.
Use MRI compatibility mode. Using this option causes GASP to
accept the syntax and pseudo-ops used by the Microtec Research
Write the output in a file called OUTFILE. If you do not use the
`-o' option, GASP writes its output on the standard output stream.
Print line numbers. GASP obeys this option _only_ if you also
specify `-s' to copy source lines to its output. With `-s -p',
GASP displays the line number of each source line copied
(immediately after the comment character at the beginning of the
Copy the source lines to the output file. Use this option to see
the effect of each preprocessor line on the GASP output. GASP
places a comment character (`!' by default) at the beginning of
each source line it copies, so that you can use this option and
still assemble the result.
Bypass "unreasonable expansion" limit. Since you can define GASP
macros inside other macro definitions, the preprocessor normally
includes a sanity check. If your program requires more than 1,000
nested expansions, GASP normally exits with an error message. Use
this option to turn off this check, allowing unlimited nested
Display the GASP version number.
The input file names. You must specify at least one input file;
if you specify more, GASP preprocesses them all, concatenating the
output in the order you list the INFILE arguments.
Mark the end of each input file with the preprocessor command
The GNU Binary Utilities, Roland H. Pesch (October 1991);