Writing a kernel in C

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Azh321

Joined: 27 Jan 2005
Posts: 12

Azh321 10 May 2005, 01:34

Well im not too good with asm, I mean I can write a few things in asm for DOS but only simple stuff. I have the bootloader, and it loads up the kernel, though it doesnt do anything. I was wondering if someoen can help me get some of the basic functions coded in asm so that I can code the kernel in C. Such as something to print text and such. (btw, its in protected mode 32bit)

10 May 2005, 01:34

Azh321

Joined: 27 Jan 2005
Posts: 12

Azh321 10 May 2005, 01:38

One of my friends showed me something like this for printing text, but I still dont know how to implement that into a function to be used in C
(this is nasm btw)

Code:

        ORG   0xFF800000

        BITS 32

SEGMENT .data
message db "Message Here",0

SEGMENT .text
start:
        mov     edi, 0xB8000
        mov     esi, message
        mov     ah, 7           ;Text attribute
.again: lodsb
        stosw
        test    al, al
        jnz     .again

        jmp short

10 May 2005, 01:38

asmdemon

Joined: 18 Jan 2004
Posts: 97
Location: Virginia Beach, VA

asmdemon 10 May 2005, 10:39

http://www.osdever.net/tutorials/brunmar/tutorial_03.php

This shows how to go from boot to c based kernel. If you look at the first tutorial, http://www.osdever.net/tutorials/brunmar/tutorial_02.php?the_id=18, it shows how and what to do to get into protected mode.

10 May 2005, 10:39

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