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Worm64

Call winapi functions from inline asm

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A fost un mic pariu cu @Usr6.M-am gandit sa il postez aici pentru cine vrea sa foloseasca functii din windows.h in asm.


#include "windows.h"

char a2[]="usr6";
char a3[]="Salut";
int main()
{
__asm
{
mov eax,0
push eax
mov eax,offset a3
push eax
mov eax,offset a2
push eax
mov eax,0
push eax
call DWORD PTR MessageBox
pop ebx
pop ebx
pop ebx
pop ebx
}
}

Edited by Worm64
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Nu e nevoie sa pui totul in EAX inainte de push.

Iar eliberarea memoriei NU se face pentru WinAPI (ex, MessageBox) deoarece au calling convention __stdcall. Functiile din C au calling convention __cdecl si acolo e necesara acea secventa "pop ebx..." dar nu se face asa, se face mai rapid cu incrementarea ESP-ului: add ESP, 0x10 (adica 16 bytes).

Info:

1. Calling Conventions Demystified - CodeProject

2. Using Win32 calling conventions

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