;NAME:AYUSH ARVIND HOWALE
;ROLL NO.:218
;SUB: MICROPROCESSOR
section .data
nummsg db "***Program to find Factorial of a number*** ",10
db "Enter the number : ",
nummsg_len equ $-nummsg
resmsg db "Factorial is : "
resmsg_len equ $-resmsg
thankmsg db 10,"Thank you ",10
thankmsg_len equ $-thankmsg
zerofact db " 00000001 "
zerofactlen equ $-zerofact
section .bss
dispbuff resb 16
result resb 4
num resb 1
num1 resb 1
numascii resb 3
%macro display 2
mov rax,01
mov rdi,01
mov rsi,%1
mov rdx,%2
syscall
%endmacro
%macro accept 2
mov rax,0
mov rdi,0
mov rsi,%1
mov rdx,%2
syscall
%endmacro
section .text
global _start
_start:
display nummsg,nummsg_len
accept numascii,3
call packnum8_proc
mov [num],bl
display resmsg,resmsg_len
mov al,[num]
cmp al,01h
jbe endfact
mov bl,[num]
call proc_fact
mov rbx,rax
call disp64_proc
jmp exit
endfact:
display zerofact,zerofactlen
exit:
display thankmsg,thankmsg_len
mov rax,60
mov rdi,0
syscall
ret
disp64_proc:
mov rdi,dispbuff
mov rcx,16
dispup1:
rol rbx,4
mov dl,bl
and dl,0fh
add dl,30h
cmp dl,39h
jbe dispskip1
add dl,07h
dispskip1:
mov [rdi],dl
inc rdi
loop dispup1
display dispbuff,16
ret
packnum8_proc:
mov bx,0
mov ecx,02
mov esi,numascii
up1:
rol bl,04
mov al,[esi]
cmp al,39h
jbe skip1
sub al,07h
skip1:
sub al,30h
add bl,al
inc esi
loop up1
ret
proc_fact:
cmp bl, 1
jne do_calculation
mov ax, 1
ret
do_calculation:
push rbx
dec bl
call proc_fact
pop rbx
mul bl
ret
