[Asm] Mon système d'exploitation

%define BASE 0x100
%define KSIZE 24	;Nombre de secteur de 512 octets à charger

[BITS 16]
[ORG 0x0]
	jmp start
	
%include "fonctions.asm"

bootdrv:	db	0

;Messages
msg_start	db	'Starting...',10,13,0
msg_loadk	db	'Loading Kernel ...',10,13,0

start:
	mov [bootdrv], dl

	;Initialisation des segments en 0x07C0
	mov ax, 0x07C0
	mov ds, ax
	mov es, ax

	;Stack en 0xFFFF
	mov ax, 0x8000
	mov ss, ax
	mov sp, 0xF000
	
	;On affiche un message
	mov si, msg_start
	call print
	
;load:
	xor ax, ax
	int 0x13
	
	push es
	mov ax, BASE
	mov es, ax
	mov bx, 0
	
	mov ah, 2
	mov al, KSIZE
	mov ch, 0
	mov cl, 2
	mov dh, 0
	mov dl, [bootdrv]
	int 0x13
	pop es
	
	;Initialisation du pointeur sur la GDT
	mov ax, gdtend
	mov bx, gdt
	sub ax, bx
	mov word [gdtptr], ax
	
	xor eax, eax
	xor ebx, ebx
	mov ax, ds
	mov ecx, eax
	shl ecx, 4
	mov bx, gdt
	add ecx, ebx
	mov dword [gdtptr+2], ecx
	
	;Passage en pmode (Mode protégé)
	cli
	lgdt [gdtptr]
	mov eax, cr0
	or ax, 1
	mov cr0, eax
	
	jmp next
	
next:
	mov ax, 0x10
	mov ds, ax
	mov fs, ax
	mov gs, ax
	mov es, ax
	mov ss, ax
	mov esp, 0x9F000
	
	;saut vers le Kernel
	jmp dword 0x8:0x1000
	
hang:
	jmp hang
	
gdt:
	db 0,0,0,0,0,0,0,0
gdt_cs:
	db 0xFF,0xFF,0x0,0x0,0x0,10011011b,11011111b,0x0
gdt_ds:
	db 0xFF,0xFF,0x0,0x0,0x0,10010011b,11011111b,0x0
gdtend:

gdtptr:
	dw	0
	dd	0
	
;NOP jusqu'à 510
times 510-($-$$) db 0
dw 0xAA55

;===============
;Print
;===============
print:	;Fonction permettant l'affichage de message à l'écran
	lodsb	;en utilisant l'interruption 10h
	
	or al, al	;Si al = 0
	jz done	;Done
	
	mov ah, 0Eh
	mov bx, 0007
	int 0x10
	
	jmp print
done:
	ret
;===============
;/Print
;===============

extern void scrollup (unsigned int);
extern void print (char *);
extern void clrscr (void);

int main();

void _start (void) 
{
	main();
}

int main (void) 
{
	clrscr();
	print("un message\n");
	while(1);
}

#ifndef _CONIO_H_
#define _CONIO_H_

	void scrollup (unsigned int);
	void print (char*);
	void clrscr (void);

#endif

#ifndef _SCREEN_H_
#define _SCREEN_H_

	#define RAMSCREEN 0xB8000
	#define SIZESCREEN 0xFA0
	#define SCREENLIM 0xB8FA0

	extern char kX;
	extern char kY;
	extern char kattr;

#endif

#include "../includes/screen.h"

	char kX = 0;
	char kY = 10;
	char kattr = 0x07;

#include "../includes/screen.h"
#include "../includes/conio.h"

void print (char* string)
{
	char* ptr;
	unsigned char* video;
	ptr = string;
	
	while (*ptr != 0) 
	{
		if (*ptr == 10) {
			kX = 0;
			kY++;
		}
		else {
			video = (unsigned char*) (RAMSCREEN + 2 * kX + 160 * kY);
			*video = *ptr;
			*(video + 1) = kattr;
			
			kX++;
			if (kX > 79) {
				kX = 0;
				kY++;
			}
		}
		ptr++;
		
		if (kY > 24) {
			scrollup (kY - 24);
		}
	}
}

#include "../includes/screen.h"
#include "../includes/conio.h"

void scrollup (unsigned int nline)
{
	unsigned char* video;
	unsigned char* tmp;
	
	for (video=(unsigned char*)RAMSCREEN ; video<(unsigned char*)SCREENLIM ; video++)
	{
		tmp = (unsigned char*) (video + nline * 160);
		
		if (tmp < (unsigned char*)SCREENLIM) {
			*video = *tmp;
		}
		else {
			*video = 0;
		}
	}
	
	kY -= nline;
	if (kY < 0) {
		kY = 0;
	}
}

#include "../includes/screen.h"
#include "../includes/conio.h"

void clrscr(void)
{
	unsigned char* video;
	
	for (video = (unsigned char*)RAMSCREEN; video < (unsigned char*)SCREENLIM; video++)
	{
		*video = 0x0;
	}
	
	kX = 0;
	kY = 0;
}

mov eax, cr0
or ax, 1
mov cr0, eax

mov byte [0xB8000], 'H'
mov byte [0xB8001], 0x57