global _start
_start :

section .text

%macro disp_macro 2
mov rax,1
mov rdi,1
mov rsi,%1
mov rdx,%2
syscall
%endm

%macro accept 2
mov rax,0
mov rdi,0
mov rsi,%1
mov rdx,%2
syscall
%endm

disp_macro msg1,len1
accept num,3
call convert
cmp al,01h
ja c1
disp_macro msg2,len2
jmp exit

c1:push rax
disp_macro msg3,len3
pop rax
mov rcx,rax
dec rcx

c2:push rax
dec rax
cmp rax,01
ja c2

c3:pop rbx
mul rbx
dec rcx
jnz c3
call display

exit:
%macro exitm 0
mov rax,60
mov rdi,0
syscall
%endm

exitm

display:
mov rsi,disparr+3
mov rcx,4

a2:mov rdx,0
mov rbx,10H
div rbx
cmp dl,09H
jbe a1
add dl,07h

a1:add dl,30H
mov[rsi],dl
dec rsi
dec rcx
jnz a2

mov rax,1
mov rdi,1
mov rsi,disparr
mov rdx,4
syscall

ret


convert:
mov rsi,num
mov al,[rsi]
cmp al,39h
jle l1
sub al,07h
l1:sub al,30h
rol al,04
mov bl,al
inc rsi
mov al,[rsi]
cmp al,39h
jle l2
sub al,07h
l2:sub al,30h
add al,bl

ret


section .data
msg1 db "Enter the Number:",0Ah
len1 equ $-msg1

msg2 db "  The factorial is 1:",0Ah
len2 equ $-msg2

msg3 db "The factorial is: ",0Ah
len3 equ $-msg3


section .bss
num resb 10
no resb 10
disparr resb 20