OSDev.org

I like write my own OS.

----------------------
I am using the loader:

boot12.asm  FAT12 bootstrap for real mode image or loader
Version 1.0, Jul 5, 1999
by John S. Fine  [email protected]

I test it with a little ASM code and runs very good.

------------------------------------------------------------------------
As first step I like to print a character on the screen using the method exposed in the guide "Mixing Assembly and C". I wrote this two programs:

----------
NASM part:

[BITS 32]
[GLOBAL _abc]
[SECTION .text]

_abc:
push ebp
mov ebp, esp
mov al,[ebp + 8] ; Get the parameter
mov ah, 0x0e
mov bl, 7
int 0x10
mov esp, ebp
pop ebp
ret

-----------
DJGPP part:

extern void abc(char c);

int main (void) {

    abc('A');
    abc('B');
    abc('C');

repeat:
goto repeat; }

---------------------------------------------------------
Then I create two objects and link it with the statements:

nasm -f coff -o nasmpart.o nasmpart.asm
gcc -ffreestanding -c -o cpart.o cpart.c
ld -Ttext 0x100000 --oformat binary -o kernel.bin

All works as the guide say!

--------
Problem:

When I load my kernel it not print the characters "ABC" but it print 3 spaces. I belive the problem is in the parameters because if a pass a canstant (like 'A') it works right.

I tried too creating an EXE file with the statements:
nasm -f coff -o nasmpart.o nasmpart.asm
gcc -ffreestanding -c -o cpart.o cpart.c
gcc -o kernel.exe bios.o system.o

And it works right!

Somebody can help me?

Thank you.