Write an x86 assembly program that:

Question

Load AL by an arbitrary number, if there is parity even, transfer 80H to the Port 0, and if there is parity odd, transfer 01H to the Port 0.

Answer 1

This is a possible solution:

section .data
number db 11001100b ; arbitrary number with parity even

section .text
global _start

_start:
mov al, byte [number] ; load AL with the arbitrary number
test al, 1 ; check parity by testing the lowest bit
jpe even ; jump if parity even
mov al, 01h ; set AL to 01H if parity odd
jmp send ; jump to send the value to Port 0
even:
mov al, 80h ; set AL to 80H if parity even
send:
out 0, al ; transfer the value in AL to Port 0
mov eax, 1 ; prepare to exit the program
xor ebx, ebx ; set the return code to zero
int 0x80 ; invoke the kernel to exit