Date: 02 Nov 1999 05:20:11 +0200 From: Giorgos Keramidas <keramida@ceid.upatras.gr> To: freebsd-questions@freebsd.org Subject: Re: NASM for FreeBSD (update...) Message-ID: <86904hshoz.fsf@localhost.hell.gr> In-Reply-To: Isaac Flemming's message of "Mon, 1 Nov 1999 11:48:48 -0500 (EST)" References: <Pine.GSO.3.96.991101095826.7261B-100000@mission.mvnc.edu>
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Isaac Flemming <iflemmin@mission.mvnc.edu> writes:
> My question now is does anyone know of any documentation that will
> tell me how to do I/O calls to the system in FreeBSD?
You have plenty of alternative choises:
(1) read the sources of the kernel to find out how to call the proper
system calls to do your I/O. This is probably the hardest way of
reinventing the wheel of Unix I/O. Try to avoid it, since writing
in C can be a little easier.
(2) use simple C calling conventions for linking your assembly programs
against the standard C library. something like the following comes
as a handy example.
push 3
push FORMAT
call printf
add esp,8
(3) write a simple function in C that does what you want, then examine
the output file produced by:
% gcc -S demo.c
you want to read demo.S after that.
> Also once I do have information about the I/O calls will I be able to
> execute the programs assembled as stand alone programs or do I have to
> call them with a .c program?
Both can work. If you link against a C program, see (2) above. To
build a standalone program, you are probably going to find (1) more
useful, in the long run.
--
Giorgos Keramidas, <keramida@ceid.upatras.gr>
"What we have to learn to do, we learn by doing." [Aristotle]
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