MIT: Addition of 2 Hexadecimal Numbers

section .data
 array db 05h,02h

section .bss
 buff resb 02

section .text
global _start
_start:
 mov rsi,array
 mov rax,[rsi]
 INC rsi
 
 mov rbx,[rsi]
 mov rax,rbx
 mov rsi,buff
 mov cl,02
 mov bl,al
 
x1: rol bl,04
 mov al,bl
 and al,0fh
 cmp al,09
 jle x2
 add al,02h

x2: add al,30h
 mov [rsi],al
 inc rsi
 dec cl
 jnz x1

 mov rax,1
 mov rdi,1
 mov rsi,buff
 mov rdx,2
 syscall

 mov rax,60
 mov rdi,00
 syscall 

SHARE SHARE SHARE