[BITS 32]

[GLOBAL start]
start:
	mov esp, _sys_stack
	jmp stublet

ALIGN 4
mboot: 
	MULTIBOOT_ALIGN     equ 1<<0
	MULTIBOOT_MEM       equ 1<<1
	MULTIBOOT_AOUT      equ 1<<16
	MULTIBOOT_MAGIC     equ 0x1BADB002
	MULTIBOOT_FLAGS     equ MULTIBOOT_ALIGN | MULTIBOOT_MEM | MULTIBOOT_AOUT
	MULTIBOOT_CHECKSUM  equ -(MULTIBOOT_MAGIC + MULTIBOOT_FLAGS)
	EXTERN code, bss, end
	
	dd MULTIBOOT_MAGIC
	dd MULTIBOOT_FLAGS
	dd MULTIBOOT_CHECKSUM

	dd mboot
	dd code
	dd bss
	dd end
	dd start

stublet:
	EXTERN kernel_main
	call kernel_main
	jmp $

[GLOBAL load_gdt]    ; Allows the C code to call gdt_flush().
[EXTERN gp]
load_gdt:
    lgdt [gp]        ; 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
	
SECTION .bss
	resb 8192
_sys_stack: