Syncboot/arch/i386/boot.s

[BITS 32] ;... somehow.

[GLOBAL start]
start:
	mov esp, _sys_stack ; Stack pointer!
	jmp stublet         ; This has a purpse. I don't know what it is, but there is one.

ALIGN 4 ; 4KB alignment, required by GRUB.
mboot:  ; This is all magic, and all of it required for GRUB to see our stuff.
	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: ; Where the kernel stuff goes.
	
	;=====================================
	;===Priority: 32 bit Protected Mode===
	;=====================================
	
	cli                             ; Interrupts be gone!
	
	xor cx, cx                      ; CX - GP, useful here.
kbempty:
	in al, 64h                      ; Read keyboard status
	test al, 02h			; Check if the buffer is full
	loopnz kbempty			; Wait until it is
	mov al, 0d1h			; Prepare a message
	out 64h, al			; And then send it to the keyboard (controller)
kbempty2:
	in al, 64h			; Read the status again
	test al, 02h			; Check if it's processed our message
	loopnz kbempty2			; And wait until it has
	mov al, 0dfh			; Prepare a different message, telling it to enable A20
	out 60h, al			; Send the message
	mov cx, 14h			; Restore the value of CX
wait_kb:				; Insinuate a 25uS delay to allow the processor to catch up
	out 0edh, ax			
	loop wait_kb	

	mov eax, cr0			; Read the control register
	or al, 1			; Set bit 1: protected mode
	mov cr0, eax			; Set the control register back
	jmp $+2				; Clear the queue
	nop				; (jump straight to kernel)
	nop

;==================================
;===32-bit Protected Mode active===
;==================================	
	; Call the kernel
	
	EXTERN kernel_main
	call kernel_main
	jmp $

[GLOBAL load_gdt]
[EXTERN gp]
load_gdt:
    lgdt [gp]        ; Load the new GDT pointer

    mov ax, 0x10
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax
    mov ss, ax
    jmp 0x08:flush
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]
[EXTERN idtp]
idt_load:
	lidt [eax]
	ret


SECTION .bss
	resb 8192
_sys_stack: