toaruos/start.asm

[BITS 32]
ALIGN 4
mboot:
	MULTIBOOT_PAGE_ALIGN	equ 1<<0
	MULTIBOOT_MEMORY_INFO	equ 1<<1
	MULTIBOOT_HEADER_MAGIC	equ 0x1BADB002
	MULTIBOOT_HEADER_FLAGS	equ MULTIBOOT_PAGE_ALIGN | MULTIBOOT_MEMORY_INFO
	MULTIBOOT_CHECKSUM		equ -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)
	EXTERN code, bss, end
	; GRUB Multiboot header, boot signature
	dd MULTIBOOT_HEADER_MAGIC
	dd MULTIBOOT_HEADER_FLAGS
	dd MULTIBOOT_CHECKSUM

; Main entrypoint
global start
start:
	mov esp, _sys_stack
	push ebx
	cli
	extern	main
	call	main
	jmp		$


; Global Descriptor Table
global gdt_flush
extern gp
gdt_flush:
	lgdt [gp]
	mov ax, 0x10
	mov ds, ax
	mov es, ax
	mov fs, ax
	mov gs, ax
	mov ss, ax
	jmp 0x08:flush2
flush2:
	ret

; Interrupt Descriptor Table
global idt_load
extern idtp
idt_load:
	lidt [idtp]
	ret

; Interrupt Service Routines
%macro ISR_NOERR 1
	global _isr%1
	_isr%1:
		cli
		push byte 0
		push byte %1
		jmp isr_common_stub
%endmacro

%macro ISR_ERR 1
	global _isr%1
	_isr%1:
		cli
		push byte %1
		jmp isr_common_stub
%endmacro

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

extern fault_handler

isr_common_stub:
	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

%macro IRQ_ENTRY 2
	global _irq%1
	_irq%1:
		cli
		push byte 0
		push byte %2
		jmp irq_common_stub
%endmacro

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

extern irq_handler

irq_common_stub:
	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


; BSS Section
SECTION .bss
	resb 8192 ; 8KB of memory reserved
_sys_stack:
; This line intentionally left blank