портативный ассемблер GNU (the portable GNU assembler.)
Описание (Description)
GNU as is really a family of assemblers. 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 pseudo-ops) and assembler syntax.
as is primarily intended to assemble the output of the GNU C
compiler "gcc" for use by the linker "ld". Nevertheless, we've
tried to make as assemble correctly everything that other
assemblers for the same machine would assemble. Any exceptions
are documented explicitly. This doesn't mean 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.
Each time you run 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 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 as no file names it attempts to read one input file
from the as standard input, which is normally your terminal. You
may have to type ctl-D to tell as there is no more program to
assemble.
Use -- if you need to explicitly name the standard input file in
your command line.
If the source is empty, as produces a small, empty object file.
as may write warnings and error messages to the standard error
file (usually your terminal). This should not happen when a
compiler runs as automatically. Warnings report an assumption
made so that as could keep assembling a flawed program; errors
report a grave problem that stops the assembly.
If you are invoking as via the GNU C compiler, you can use the
-Wa option to pass arguments through to the assembler. The
assembler arguments must be separated from each other (and the
-Wa) by commas. For example:
gcc -c -g -O -Wa,-alh,-L file.c
This passes two options to the assembler: -alh (emit a listing to
standard output with high-level and assembly source) and -L
(retain local symbols in the symbol table).
Usually you do not need to use this -Wa mechanism, since many
compiler command-line options are automatically passed to the
assembler by the compiler. (You can call the GNU compiler driver
with the -v option to see precisely what options it passes to
each compilation pass, including the assembler.)
