I need to input a string, convert it to an int, multiply it and convert it back to string then print the new string to screen.
I think i am getting the string input and converting to int correctly. It is multiplying fine i think as well. My problem is converting it back to a string. Something is going wrong. Here is my code at the moment. And sample inputs and outputs that i get at end:
; Progam 2: input/output ints
; Author: William Pognonec
section .bss
our_int resb 30
new_int resb 30
int_len resd 1
newint_len resd 1
section .data
welcome_msg db "Welcome to program 2.",13,10
len1 equ $ - welcome_msg
prompt_int db "Please enter an integer."
len2 equ $ - prompt_int
section .text
global _start
_start:
;write welcome message
mov edx, len1
mov ecx, welcome_msg
mov ebx, 1
mov eax, 4
int 0x80
;write prompt for int
mov edx, len2
mov ecx, prompt_int
mov ebx, 1
mov eax, 4
int 0x80
;now read int
mov edx, 30
mov ecx, our_int
mov ebx, 2
mov eax, 3
int 0x80
;now save size of string input
dec eax
mov dword [int_len], eax
;now convert number
mov edi, 10
mov ecx, [int_len]
mov esi, our_int
xor eax, eax
xor ebx, ebx
mov bl, [esi]
cmp bl, '-'
jne next_check
inc eax
inc esi
dec ecx
jmp done_sign
next_check: cmp bl, '+'
jne done_sign
inc esi
dec ecx
done_sign: push eax
l1: mov bl, [esi]
; cmp bl, 30h
; jb error
; cmp bl, 39h
; ja error
sub bl, 30h
mul edi; eax = eax * 10
mov bh, 0
add eax, ebx
inc esi
loop l1
pop ebx
cmp ebx, 1
jne done
neg eax
done: ;now tripple eax
mov edi, 3
mul edi
;convert int to string
mov esi, new_int
mov ebx, 10
xor ecx, ecx
cmp eax, 0
jge skip_negate
neg eax
push dword 1; remember neg
jmp start_convert
skip_negate: push dword 0
start_convert: xor edx, edx
div ebx
add dl, 30h; convert ascii
push edx
inc ecx
cmp eax, 0
jne start_convert
mov eax, ecx
inc eax
inc esi
lp2: pop edx
mov [esi], dl
inc esi
loop lp2
pop edx
cmp edx, 1
jne positive
mov esi, new_int
mov [esi], byte '-'
jmp finish
positive: mov esi, new_int
mov [esi], byte '+'
finish:
mov [newint_len], eax
;print out new int
mov edx, dword [newint_len]
mov ecx, new_int
mov ebx, 1
mov eax, 4
int 0x80
error:
mov ebx, 0
mov eax, 1
int 0x80
;;; Sample outputs ;;;
input:
333
output:
+999
input:
-333
output:
-3999
It seems to work for positive integers.
For negative ones, it gives the correct answer beyond the -3 part.
Any help would be appreciated.
Thanks
You can email me at ubertoast AT gmail DOT com
