From: nitehawk91 AT aol DOT com
Newsgroups: comp.os.msdos.djgpp
Subject: DJGPP stack when calling a function? Please help.
Date: 13 Apr 1997 11:15:10 GMT
Organization: AOL Bertelsmann Online GmbH & Co. KG http://www.germany.aol.com
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Message-ID: <19970413111500.HAA07345@ladder01.news.aol.com>
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To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Greetings !

I have a problem accessing function parameters from an Assembler module.
Could someone please explain to me how the paramers of an function are pushed onto the stack with DJGPP ?
The basic idea I have (from the cofftest.asm that came with nasm) is :

parameters;
return address; 4 bytes
stack pointer ; 4 bytes

I have a function that looks like this : func(short, short, short)
Now the stack would look like :

short 3; 2 byte
short 2; 2 byte
short 1; 2 byte
return adress ; 4 byte
stack pointer ; 4 bytes

Now I tied to access the three parameters as following :

mov eax, [esp+8] ; short 1 to eax
mov ebx, [esp+10] ; short 2 to ebx
mov ecx, [esp+12] ; short 3 to ecx

This compiles and the programm works fine, but I get idiotic results.
(BTW : The assembler function doesn't return a value)

Whats going wrong here ?

2. Pointer access problem :
assume I have char string[] = {'h','e','l','l','o'}; 
In C I could access the 'e' for example with string[1] or *(string+1).
How can I make this in Nasm ?
I have declared [EXTERN _string]
Tried to access the 'e' with mov eax,[_string+1]
This doesn't work also. Why ?

Please help me.

Thank's

Matthias
<NiteHawk91 AT aol DOT com>

*Aritficial intelligence is better than natural stupidity