ExtendedProgram.asm

section .text

jmp EnterProtectedMode

%include "gdt.asm"
%include "Print.asm"


EnterProtectedMode:
	call EnableA20
	cli
	lgdt [gdt_descriptor]
	mov eax, cr0
	or eax, 1
	mov cr0, eax
	jmp codeseg:StartProtectedMode

EnableA20:
	in al, 0x92
	or al, 2
	out 0x92, al
	ret

[bits 32]

%include "CPUID.asm"
%include "SimplePaging.asm"

StartProtectedMode:

	mov ax, dataseg
	mov ds, ax
	mov ss, ax
	mov es, ax
	mov fs, ax
	mov gs, ax

	mov [0xb8000], byte 'H'
	mov [0xb8002], byte 'e'
	mov [0xb8004], byte 'l'
	mov [0xb8006], byte 'l'
	mov [0xb8008], byte 'o'
	mov [0xb800a], byte ' '
	mov [0xb800c], byte 'W'
	mov [0xb800e], byte 'o'
	mov [0xb8010], byte 'r'
	mov [0xb8012], byte 'l'
	mov [0xb8014], byte 'd'

	call DetectCPUID
	call DetectLongMode
	call SetUpIdentityPaging
	call EditGDT
	jmp codeseg:Start64Bit

[bits 64]

[extern _start]

Start64Bit:
	mov edi, 0xb8000
	mov rax, 0x1f201f201f201f20
	mov ecx, 500
	rep stosq
	
	call _start
	
	jmp $
	
times 2048-($-$$) db 0