2-digit Fibonacci Solver (NASM)

zeroliken 0 1K Views

I bet all Computer Science related courses would learn low level or machine level languanges in due time and in our university we used the portable 80x86 assembler NASM for our Assembly code

So here's my experimentation on how to use "functions" and recursion using a Fibonacci Solver as a test case
As you may notice the code only output the final outcome of the Fibonacci sequence instead of printing every number for all steps. I might or might not update this depending on my free time and motivation but for now here's what i've done :)

; @uthor: zeroliken
; Decription: two-digit fibonacci
; input: To input enter a two digit number followed by enter e.g. 01, 09, 13 etc.
 
section .data
	ask1 db 'Compute Fibonacci: Enter a 2-digit number (e.g. 07)' , 10, 13
	promptlen1 equ $-ask1

	end db ' ', 10, 13
	endlen equ $-end

	checker dw 1
	fibo dw 0
	temp dw 0
	temp1 dw 0
	temp2 dw 0

section .bss
	ent resb 1
	x1 resb 1
	x2 resb 1

section .text
	global _start
_start:

	mov eax, 4
	mov ebx, 1
	mov ecx, ask1
	mov edx, promptlen1
	int 80h

	mov eax, 3		
	mov ebx, 0
	mov ecx, x1							
	mov edx, 1
	int 80h
	sub byte [x1], 30h

	mov eax, 3
	mov ebx, 0
	mov ecx, x2					
	mov edx, 1
	int 80h
	sub byte [x2], 30h

	mov eax, 3
	mov ebx, 0
	mov ecx, ent
	mov edx, 1
	int 80h

	mov al, [x1]
	mov byte [temp], 10
	mul byte [temp]
	mov [x1], al
	add al, [x2]
	mov [fibo], al

	sub esp, 2
	push word[fibo]
	call computefibo
	pop word[fibo]

	mov bl, 10			;convert to 2 digit
	mov al, [fibo]
	mov ah, 0
	div bl							
	
	mov [x1], al			;put the first digit to x1 and 2nd to x2
	add byte [x1], 30h							
	mov [x2], ah
	add byte[x2], 30h

	mov eax, 4
	mov ebx, 1
	mov ecx, x1
	mov edx, 1
	int 80h
	
	mov eax, 4
	mov ebx, 1
	mov ecx, x2
	mov edx, 1
	int 80h

	mov eax, 4
	mov ebx, 1
	mov ecx, end
	mov edx, endlen
	int 80h
	
	mov eax, 1
	mov ebx, 0
	int 80h

	computefibo:
		mov ebp, esp
		cmp word [ebp+4], 0
		je returnzero
		cmp word [ebp+4], 1
		je returnone
	
		; computefibo(n-1)

		mov ax, word[ebp+4]
		dec ax
		sub esp,2
		push ax
		call computefibo
		pop word[temp1]
		mov ebp, esp

		; computefibo(n-2)
		
		push word[temp1]	;save the previous number by pushing it to a stack 
		mov bx, word[ebp+4]
		sub bx, 2
		sub esp, 2
		push bx
		call computefibo
		pop word[temp2]
		pop word[temp1]		;pop the previous number
		mov ebp, esp
		
		
		mov ax, word[temp1]
		add ax, word[temp2]	;computefibo(n-1) + computefibo(n-2)
		mov [ebp+6], ax
		jmp exit

		returnone:
		mov word[ebp+6], 1
		jmp exit

		returnzero:
		mov word[ebp+6], 0
		jmp exit

	exit:
	ret 2
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