i want hook function x86 executeable. that's functions prototype decompiled hex-rays plugin ida: int __userpurge sub_43ce70<eax>(int a1<eax>, int a2, char a3, int a4, int a5, int a6) so function acception eax first parameter , returns same register. i tried following function wrapper: int the_wrapper(int a2, unsigned a3, int a4, int a5, int a6) { int a1; _asm { mov [a1], eax }; char bstring[50]; sprintf(bstring,"a1: %u, a2: %u, a3: %d, a4: %d, a5: %d, a6: %d",a1,a2,a3,a4,a5,a6); logs(bstring); int rtn; _asm{ push a6 push a5 push a4 push a3 push a2 mov eax, [a1] call the_function mov [rtn], eax }; return rtn; } for reason it's not working , crashed everytime function gets called. you need declare wrapper same calling convention function trying wrap. depending on convention (the common being cdecl , stdcall depends o...