I made my own implementation of strlen in assembly, but it doesn't return the correct value. It returns the string length + 4. Consequently. I don't see why.. and I hope any of you do...
Assembly source:
section .text
[GLOBAL stringlen:] ; C function
stringlen:
push ebp
mov ebp, esp ; setup the stack frame
mov ecx, [ebp+8]
xor eax, eax ; loop counter
startLoop:
xor edx, edx
mov edx, [ecx+eax]
inc eax
cmp edx, 0x0 ; null byte
jne startLoop
end:
pop ebp
ret
And the main routine:
#include <stdio.h>
extern int stringlen(char *);
int main(void)
{
printf("%d", stringlen("h"));
return 0;
}
Thanks
Thanks for your answers. Under here working code for anyone who has the same problem as me.
section .text
[GLOBAL stringlen:]
stringlen:
push ebp
mov ebp, esp
mov edx, [ebp+8] ; the string
xor eax, eax ; loop counter
jmp if
then:
inc eax
if:
mov cl, [edx+eax]
cmp cl, 0x0
jne then
end:
pop ebp
ret