CODEWITHSUNDEEP
assemblymasmx86-16
user3694136
user3694136

Reputation: 3

Assembly - text to number

I am trying to convert texto to number. Exemple I digit "321" and I need to conver it to number: 321.

First i copy to text

f:  mov al,es:[bx]
    mov texto[di],al        
    inc bx
    inc bx
    inc di
loop f

Then I want to convert to number.

xor di, di
mov cl, 10

li:
mov al,texto[di]
mov numero[di],al
sub al, 48
mul cl
xor al, al
inc di
loop li

The first code I think is ok, but the second is wrong. I don't get it.

Upvotes: 0

Views: 203

Answers (2)

Gene
Gene

Reputation: 46970

It can help to code in a HHL before assembly. If the algorithm is at all complex, run it in the HLL so that you're sure it works before committing to assembly code. For example, this:

char text[] = "321";
int n_chars = 3;
int val = 0;
int i = 0;

next:
  val = 10 * val + text[i++] - '0';
  if (--n_chars) goto next;

In MASM, 

mov bl, 10 ; constant multiplier
mov cl, 3  ; n_chars = 3
xor ax, ax ; val = 0
xor si, si ; i = 0 

next:
  mul bl           ; val = 10 * val
  add ax, text[si] ; val = val + text[i]
  sub ax, '0'      ; val = val - '0'
  inc si           ; i++
  loop next        ; if (--nChars) goto next

Upvotes: 2

Breaksu
Breaksu

Reputation: 11

you just want to convert "321" to 321?

You have to sub 30h to each value and add it to the final number. example:

.8086
.model small
.stack 2048

DATA segment para public 'data' 
number db '321$' 
final dw 0
DATA ends

CODE segment para public 'code'
    assume CS:CODE, DS:DATA

main proc 
mov ax, DATA 
mov ds, ax 



    mov si,0
    mov cx,10
    xor bx,bx 

    cicle:
        mov ax,final
        mul cx

        mov final,ax

        mov bl,number[si]
        sub bl,30h

        add final,bx

        inc si 

        cmp number[si],'$'
        jne cicle

        MOV AH,4ch
        INT 21h
        MAIN endp 

        CODE ends
        END MAIN

I know it is not fully functional and you should expect some bugs.

EDIT: I just wanted to give an example so he could understand. Here is a full functional code. As long as the digit are before '$' it will work perfectly.

Upvotes: 1

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