bits 32

global start

; multiboot header
MODULEALIGN equ  1<<0  
MEMINFO     equ  1<<1
VIDEOINFO   equ  1<<2
FLAGS       equ  MODULEALIGN | MEMINFO | VIDEOINFO
MAGIC       equ  0x1BADB002
CHECKSUM    equ  -(MAGIC + FLAGS)
 
align 4
section .__mbHeader
MultiBootHeader:
	dd MAGIC
	dd FLAGS
	dd CHECKSUM

section .text

STACKSIZE equ 0x4000                  ; that's 16k.

start:
	XCHG BX, BX ; magic breakpoint

	mov ecx, eax

	; setup initial stack
	mov esp, stack+STACKSIZE

	; Verify booted with multiboot compliant bootloader
	cmp ecx, 0x2BADB002
	jne .bad

	push esp
	push ebx

	extern k_main
	call k_main

	cli
	hlt

; Show error message, and halt system
.bad:

	extern ConsoleClear
	extern ConsoleWrite
	extern CommandOsver

	call ConsoleClear
	call CommandOsver

	mov eax, [ErrorColor]
	push eax
	push ErrorString
	call ConsoleWrite

	cli
	hlt


; some variables
ErrorString			db 0xA, "%#! Fatal error: Not booted with multiboot compliant bootloader (e.g. GRUB).", 0x0
ErrorColor			db 0x0C

; stack
section .bss
align 32
stack:
    resb STACKSIZE           ; This reserves memory for stack