Write x86 ALP to find the factorial of a given integer number on a command line

%macro disp 2
mov rax,01h
mov rdi,01h
mov rsi ,%1
mov rdx,%2
syscall
%endmacro

%macro inn 2
mov rax,00h
mov rdi,00h
mov rsi,%1
mov rdx,%2
syscall
%endmacro

section .data
msg1 db "Enter the 8 bit number:",0ah,0dh
len1 equ $  -msg1

msg2 db "The factorial of given 8 bit number is:",0ah,0dh
len2 equ $  -msg2

msg3 db "The factorial for 0 or 1 is:",0ah,0dh
len3 equ $  -msg3

zeroonefact db "0001"
zeroonefactlen equ $-zeroonefact

section .bss
num resb 3
res resb 16

section .text
global _start
_start:

disp msg1, len1
inn num, 3
call accept

xor rax, rax
mov ax,bx
cmp ax,01h
jbe onezero

call factorial
call display
mov rax,60
mov rdi,0
syscall



onezero:
disp msg3,  len3
disp zeroonefact,  zeroonefactlen

;exit:


accept:
       mov rsi,num
       mov cl,04
       xor rbx,rbx
       mov ch,02
       up:
       cmp byte[rsi],39h
       jng sk
       sub byte[rsi],07h
       sk:
       sub byte[rsi],30h
       rol bl,cl
       add bl,[rsi]
       inc rsi
       dec ch
       jnz up
ret

factorial:
xor rbx, rbx
mov rbx,rax
up1:sub rbx ,01
mul rbx
cmp rbx,01
jne up1
ret

display:
mov rsi,res
mov ch,16
mov cl,04

again1:
rol rax,cl
mov bl,al
and bl,0fh
cmp bl,09h
jng skip2
add bl,07h
skip2:
add bl, 30h
mov [rsi],bl
inc rsi
dec ch
jnz again1

disp msg2, len2
disp res, 16
ret