
BITS 32

GLOBAL fact

SECTION .text

fact:

    mov  eax, [esp+4]	; n в eax
    cmp  eax, 1
    je	 ret1		; 1 ! = 1

    push ecx		; save used ecx

    dec	 eax		; eax = n-1
    push eax
    call fact		; в eax (n-1)!
    pop  ecx		; ecx = n
    inc  ecx
    mul  ecx		; eax *= ecx

    pop  ecx		; restore used ecx

ret1:
    ret
