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; multiboot header constants
MBALIGN equ 1 << 0
MEMINFO equ 1 << 1
MBFLAGS equ MBALIGN | MEMINFO
MAGIC equ 0x1BADB002
CHECKSUM equ -(MAGIC+MBFLAGS)
; multiboot header
section .multiboot
align 4
dd MAGIC
dd MBFLAGS
dd CHECKSUM
section .data
%include "arch/i386/gdt.asm"
; defines the stack
section .bss
align 16
stack_bottom:
resb 16384 ; 16 KiB
stack_top:
; temporary paging tables
align 4
boot_page_directory:
resb 4096
boot_page_table:
resb 4096
section .text
global _start:function (_start.end - _start)
_start:
cli
; setup stack
mov esp, stack_top
; push the multiboot header data into the stack for later use
push eax
push ebx
; get multiboot header data (for memory map)
;extern multiboot_main
;call multiboot_main
;extern _init
;Scall _init
lgdt [gdt_descriptor]
jmp 0x08:.gdt_jmp
.gdt_jmp:
mov ax, DATA_SEG
mov ds, ax
mov es, ax
mov fs, ax
mov gs, ax
mov ss, ax
jmp .gdt_jmp2
.gdt_jmp2:
; setup paging (to map kernel to the higher half)
;mov eax, 0
;mov cr3, eax
;mov eax, cr0
;or eax, 0x80000001
;mov cr0, eax
; setup idt
extern idt_setup
call idt_setup
extern idtr
lidt [idtr]
; initialize pic
push ebp
mov ebp, esp
mov ebx, 0x28
push ebx
mov ebx, 0x20
push ebx
extern pic_remap
call pic_remap
pop ebx
pop ebx
mov esp, ebp
pop ebp
sti
; enter the kernel
extern kernel_main
call kernel_main
; indefinite loop once system exits
;cli
.hang: hlt
jmp .hang
.end:
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