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From: lzago@eso.org (Lorenzo Zago)
Newsgroups: comp.sys.amiga.programmer
Subject: How are registers assigned to C functions args ?
Message-ID: <1991Jun10.080025.27797@eso.org>
Date: 10 Jun 91 08:00:25 GMT
Article-I.D.: eso.1991Jun10.080025.27797
Sender: news@eso.org
Organization: ESO - European Southern Observatory, Garching by Munich
Lines: 26
Originator: lzago@pj1

I am trying to write a shared library callable both in AmigaBasic and C.
Because I am very poor in assembler I wish to write all the library 
functions in C.
I am using LibTool from Jeff Glatt and I modify the generated library 
assembler code to push the arguments so that they can be "seen" also when 
calling from AmigaBasic.
Everything is fine as long as the arguments of all my library functions
are "long"s and the function just does simple aritmetics. In these cases
it appears that my arguments are found in registers d0,d1,d2,etc.

However, when in my library functions there is a call to an Intuition
function, I find that an argument, say a window pointer, is now in a0.
In order to modify correctly the code generated by LibTool and to write
the correct .fd file (also required to get the .bmap file for AmigaBasic)
I need to identify, or better, to define which registers are actually used.

Can anyone help ?      Thanks in advance.

Lorenzo Zago                         Uucp: lzago@eso.uucp or eso!lzago
ESO - European Southern Observatory  Earn: lzago@dgaeso51
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