Problem converting integer to ASCII code in x86 assembly
I am trying to use the code below to convert an integer in ax
to ASCII codes. But running it outputs 5开发者_如何学Go15, rather than 513 as I expected. Where is the error?
stk segment
dw 32 dup(0)
stk ends
dts Segment
posnum db 6 dup(0) ;0<x<65536;
dts ends
cds Segment
Assume cs:cds , ds:dts,ss:stk
Main Proc Far
mov ax,seg dts
mov ds,ax
mov es,ax
xor ax,ax
mov ax,513
mov di,offset posnum
Call ConvertPositive
mov ah,09h
mov dx ,offset posnum
int 21h
main_finish:
mov ah,08h
int 21h
mov ax,4c00h
int 21h
Main endp
cds Ends
procs segment
assume cs:procs
ConvertPositive proc far
xor dx,dx
xor cx,cx
mov bl,10
mov bh,0
divloop:
mov dx,0
div bx
add dl,30h
mov byte ptr [si],dl
inc cl
inc si
cmp ax,0
jne divloop
enddiv:
dec si
copy:
std
LODSB
cld
STOSB
loop copy
mov byte ptr [di],'$'
ret
ConvertPositive endp
procs ends
end Main
SI
is not initialized. It should point to a buffer allocated for the reverse order digits.
Your divide loop looks good
#include <stdio.h> #include <stdlib.h> #include <string.h> int main ( void ) { unsigned int ax; unsigned int dx; ax=513; while(ax) { dx=ax%10; ax=ax/10; printf("%c",dx+0x30); } printf("\n"); }
I get 315 out of the above loop.
I suspect when you try to flip the string around your 5 is stomping on your 3. Try a number like 713 and see if it results in 717. 523 if you get 525, etc. I am guessing 1234 results in 4334.
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