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I do not get any compile or link error but when it comes to execution - The program does print 'Hello World' but then it dumps a stack trace on the screen.

Stack Trace with output 'Hello World':

Hello WorldExiting due to signal SIGSEGV
General Protection Fault at eip=0000160a
eax=00000dff ebx=000001c1 ecx=00000000 edx=0000033f esi=0000160e edi=0000d762
ebp=0008d718 esp=0008d718 program=F:\OS\SOURCE\PRINT\CALLPR~1.EXE
cs: sel=01a7  base=01c10000  limit=0009ffff
ds: sel=01af  base=01c10000  limit=0009ffff
es: sel=01af  base=01c10000  limit=0009ffff
fs: sel=017f  base=00005c10  limit=0000ffff
gs: sel=01bf  base=00000000  limit=0010ffff
ss: sel=01af  base=01c10000  limit=0009ffff
App stack: [0008d760..0000d760]  Exceptn stack: [0000d6c0..0000b780]

Call frame traceback EIPs:
  0x0000160a
  0x0000162e
  0x00002e88
----------------------------------------------------------------------

Source Code:

//C Code to call print defined in ASM
#include<stdio.h>

int main()
{
char *s = "Hello World";
print(s);
}

//ASM code to print
global _print

SEGMENT .text
[BITS 32]

_print:
        push ebp
        mov ebp, esp
        mov esi,[ebp+8]
.continue
        lodsb
        mov ah,0x0E
        or al,al
        jz .end
        int 0x10
        jmp .continue
.end

You are trying to call a BIOS interrupt, and your process is running in v86 mode.

If you were to dump this to a bootdisk and run it in protected mode, then it would (probably) work fine.

Where's the mov esp, ebp / pop ebp / ret at the end of your ASM routine?

What assembler are you using to compile the source code?  I've noticed that this sometimes happens to me when I use MS-DOS debug but not when I use a normal assembler.
~ TripleFault !)

hi everybody. Dear Jamethiel you are perfectly right.

I did a stupid thing. Actually if you could see the msg board - I had asked help on passing pointer values to asm code and with help from you all, I figured out a way(I'm really greatful to u all). I was a bit too excited and wanted to immediately try passing strings. And in the hurry I didn't add the following code:

mov esp, ebp / pop ebp / ret

Anyway friends - Now that I have added it- It works Fine.
Here is the code. The assembler that I use: NASM (info for


//ASM Code
global _print

SEGMENT .text
[BITS 32]

_print:
        push ebp
        mov ebp, esp
        mov esi,[ebp+8]
.continue
        lodsb
        mov ah,0x0E
        or al,al
        jz .end
        int 0x10
        jmp .continue
.end
        pop ebp
        ret

//C Code
#include<stdio.h>

int main()
{
char *s = "Hello World";
print(s);
}

Thanks again
modshah

PS: I am really happy to join this community. Though at the moment, I am just a beginner, in future I will be a contributor. Once again thanks to all those selfless soles out there who help us (newbies).

Dear TripleFault, actually there was no problem with the assembler. Actually it was my mistake(please see the last post from me in this msg thread). I had not coded the 'ret' in the procedure call.

As for the assembler, I use NASM.

Thanks
modshah

Aside from the bug that you found earlier, I see another problem here.  You must be running in real mode (you are using a BIOS call), so your assembly code should be BITS 16, not BITS 32.  I don't think that for this function that will cause a problem, but it might for other functions.  It seems to me that because NASM thinks you are in a 32-bit segment, it does not insert the overrides, so when you code 'push ebp' it is actually outputting the 16-bit version 'push bp', and likewise for the other lines.

That is, unless I'm missing something here...