#include <stdio.h>
#include <stdlib.h>

__declspec(naked) void asm_factorial(int& n) {
    __asm {
        mov eax, [esp + 4]
        mov ebx, eax
        push ebx
        mov ebx, [eax]
    StartLoop:
        dec ebx
        imul eax, ebx
        cmp ebx, 1
        jg StartLoop
        pop ebx
        push eax
        mov eax, [ebx]
        mov ebx, eax
        pop eax
        mov [eax], ebx
        ret
    }
}

int main(int argc, char* argv[]) {
    int test = 4;
    asm_factorial(test);
    printf("factorial result: %i\n", test);

    system("PAUSE");
    return 0;
}