Question

Write the following x86 assembly program to run in masm:

3. X is a signed array of bytes. Convert all negative values in the array to positive.

(a) Use conditional jumps only.

(b) Repeat but using conditional directives only

Answer 1

section .data
ncnt db 0
pcnt db 0
array: dw 80H,4CH,3FH
len equ 3
msg1: db 'positive numbers are:',0xa
len1: equ $-msg1
msg2: db 'negative numbers are:',0xa
len2: equ $-msg2


section .bss
buff resb 02

section .text

global _start
_start:

mov rsi,array
mov rcx,03

A1:
bt word[rsi],15
jnc A
inc byte[ncnt]
jmp skip

A:
inc byte[pcnt]


skip:
inc rsi
inc rsi
loop A1

mov rax,1
mov rdi,1
mov rsi,msg1
mov rdx,len1
syscall

mov bl,[pcnt]
mov rdi,buff
mov rcx,02



call display


mov rax,1
mov rdi,1
mov rsi,msg2
mov rdx,len2
syscall

mov bl,[ncnt]
mov rdi,buff
mov rcx,02


call display

mov rax,60
mov rdi,0
syscall

display:
rol bl,4
mov al,bl
and al,0FH
cmp al,09
jbe B
add al,07h

B:
add al,30H
mov[rdi],al
inc rdi
loop display


mov rax,1
mov rdi,1
mov rsi,buff
mov rdx,02
syscall

ret