Hi mk8,
You're on the right track. (one of several ways to do this) There are a couple of ways to know when to stop "pop"ing. One way would be to "push" some "guard value" first (anything but 0..9 would do) and watch for it as you "pop". An even more obvious way would be to count 'em...
There's another little issue that may be screwing you up. "div ebx" calculates "edx:eax/ebx", not just "eax/ebx". We might want a 32-bit by 32-bit divide, but that's not what the instruction does, it's a 64-bit by 32ibit divide. This "bug" bites almost every beginner - it's almost a "rite of passage". If edx >= ebx, the quotient won't fit in eax, causing an exception that will crash your program. If you had added '0' to edx before pushing it, you might run into this. Since you add '0' later, it just gives wrong results (almost "worse", actually). We need to zero edx before the "div" every time through the loop.
Here's your code with a couple of minor changes...
section .text
global _start
_start:
mov eax, 12345
xor esi, esi ; digit counter
; could set ebx here and leave it, too
intoascii:
cmp eax, 0
je done
mov ebx, 10 ; inside loop..mhm(?)
; could do it outside the loop, but this is okay
xor edx, edx ; this needs to be inside the loop!
div ebx ; i hope result eax/abx is in eax and remainder is in edx
; close. edx:eax/ebx
push edx ; push remainder on stack
inc esi ; count the digit
jmp intoascii
done:
; xor esi,esi
print:
; this would be okay if we know we've got 5 digits
;cmp esi, 5 ; len[12345], every digit from stack
;je endprint
mov eax, 4
mov ebx, 1
mov ecx, 65 ; ?
pop ecx
add ecx, 30h ;int to ascii number
; you're putting 4 bytes in a one-byte variable
; mov [temp], ecx
mov [temp], cl
mov ecx, temp
mov edx, 1
int 80h
; inc esi
; jmp print
dec esi
jnz print
endprint:
mov eax, 1
mov ebx, 0
int 80h
section .data
segment .bss
temp resb 1
That's untested, but I think it'll work. Don't hesitate to fiddle with it and try different things. If the number is 0, you probably want to print '0' rather than ignore it entirely. Just move the test for eax=0 a little later in the loop. An alternative to pushing/popping remainders to get 'em in the right order is to put 'em in the buffer (you'll need a buffer big enough) from the "end" and work back toward the "beginning". This may not get you all the way to the beginning before you run out of digits, so you'll need to keep track of the "print position" and the count. Or you can pad the buffer with spaces - "right justified" numbers look nice if you're printing a column of numbers, if you're printing it "in line" you probably don't want the spaces. Make it "work" first, you've got the rest of your life to make it "elegant".
(after looking again at the above code, I've got a bug in it. If esi is zero, "dec esi" is going to loop for a long time! You probably want to print at least one digit anyway. See if you can fix it.)
Best,
Frank
