MBOOT_ALIGN    equ 1<<0
MBOOT_MEMINFO  equ 1<<1
MBOOT_FLAGS    equ MBOOT_ALIGN | MBOOT_MEMINFO
MBOOT_MAGIC    equ 0x1BADB002
MBOOT_CHECKSUM equ -(MBOOT_MAGIC + MBOOT_FLAGS)

[BITS 32]

[GLOBAL mboot]
[SECTION .multiboot]
ALIGN 4
mboot:
	dd MBOOT_MAGIC
	dd MBOOT_FLAGS
	dd MBOOT_CHECKSUM
	
SECTION .bss
ALIGN 16
stack_bottom:
RESB 16384
stack_top:


SECTION .text
[GLOBAL _start]
[EXTERN kernel_main]

_start:
	push ebx
	
	cli
	call kernel_main
	jmp $

[GLOBAL load_gdt]    ; Allows the C code to call gdt_flush().

load_gdt:
    mov eax, [esp+4] ; Get the pointer to the GDT, passed as a parameter.
    lgdt [eax]        ; Load the new GDT pointer

    mov ax, 0x10      ; 0x10 is the offset in the GDT to our data segment
    mov ds, ax        ; Load all data segment selectors
    mov es, ax
    mov fs, ax
    mov gs, ax
    mov ss, ax
    jmp 0x08:flush   ; 0x08 is the offset to our code segment: Far jump!
flush:
    ret
	
%macro ISR 1
	global isr%1
	isr%1:
		cli
		push byte 0
		push byte %1
		jmp isr_common
%endmacro

%macro ISR_ERR 1
	global isr%1
	isr%1:
		cli 
		push byte %1
		jmp isr_common
%endmacro

%macro IRQ 2
	global irq%1
	irq%1:
		cli
		push byte 0
		push byte %2
		jmp irq_common
%endmacro

ISR 0
ISR 1
ISR 2
ISR 3
ISR 4
ISR 5
ISR 6
ISR 7
ISR_ERR 8
ISR 9
ISR_ERR 10
ISR_ERR 11
ISR_ERR 12
ISR_ERR 13
ISR_ERR 14
ISR 15
ISR 16
ISR_ERR 17
ISR 18
ISR 19
ISR 20
ISR 21
ISR 22
ISR 23
ISR 24
ISR 25
ISR 26
ISR 27
ISR 28
ISR 29
ISR_ERR 30
ISR 31

IRQ 0, 32
IRQ 1, 33
IRQ 2, 34
IRQ 3, 35
IRQ 4, 36
IRQ 5, 37
IRQ 6, 38
IRQ 7, 39
IRQ 8, 40
IRQ 9, 41
IRQ 10, 42
IRQ 11, 43
IRQ 12, 44
IRQ 13, 45
IRQ 14, 46
IRQ 15, 47
	
extern fault_handler

isr_common:
	pusha
	push ds
	push es
	push fs
	push gs
	mov ax, 0x10
	mov ds, ax
	mov es, ax
	mov fs, ax
	mov gs, ax
	mov eax, esp
	push eax
	
	mov eax, fault_handler
	call eax
	
	pop eax
	pop gs
	pop fs
	pop es
	pop ds
	popa
	add esp, 8
	iret

extern irq_handler

irq_common:
	pusha
	push ds
	push es
	push fs
	push gs
	mov ax, 0x10
	mov ds, ax
	mov es, ax
	mov fs, ax
	mov gs, ax
	mov eax, esp
	push eax
	mov eax, irq_handler
	call eax
	pop eax
	pop gs
	pop fs
	pop es
	pop ds
	popa
	add esp, 8
	iret

[GLOBAL idt_load]
idt_load:
	mov eax, [esp+4]
	lidt [eax]
	ret