Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!iuvax!ndcheg!ndmath!milo
From: milo@ndmath.UUCP (Greg Corson)
Newsgroups: comp.sys.mac.programmer
Subject: Calling Assembly Language Subroutines from MPW C
Keywords: MPW, C, Assembly, 68000
Message-ID: <1455@ndmath.UUCP>
Date: 23 Jun 89 14:59:55 GMT
Organization: Math. Dept., Univ. of Notre Dame
Lines: 28

Suddenly, for speed reasons, I find myself needing to write an assembly language
routine that can be called from my C program and passed arguments.

The assembly routine contains some special purpose graphics code and will need
to use almost all of the 68000's registers.

I haven't been able to find a good example of how to write an assembly
language routine that is callable from C and can be passed arguments from
the C program.  I also need to know what registers need to be saved in the
assembly routine and restored when it returns to the C caller.

If anybody has any examples of this, please send them on...I would REALLY
appreciate it.  A simple do-nothing program shell that shows how to get
an argument and shows what registers need to be saved would be very helpful.

I've programmed in 68000 assembly before, but the compiler I was using at the
time was setup to generate the calling sequence and register saves for me.
I've never tried to write a assembly subroutines under MPW.

Thanks for the help!


Greg Corson
19141 Summers Drive
South Bend, IN 46637
(219) 277-5306 
{pur-ee,rutgers,uunet}!iuvax!ndmath!milo