asm {
start:
	;; Copy Kernel to 1 MB
	cld ; Copy forward

	mov esi, 0h40000
	mov edi, 0h100000
	mov ecx, 512 / 4 ; How many 4 bytes, right now 512 because kernel has 1 sector

	rep_movsd

	; Check longmode support
	mov eax, 0h80000000
	cpuid
	cmp eax, 0h80000001

	; This is like jb
	jc &lmns

	mov eax, 0h80000001
	cpuid
	test edx, 0h20000000
	jz &lmns

	;; Disable Paging
	; mov eax, cr0
	du8 0h0F
	du8 0h20
	du8 0hC0

	and eax, 0h7FFFFFFE

	; mov cr0, eax
	du8 0h0F
	du8 0h22
	du8 0hC0

	;; Clearing the tables
	mov edi, 0h30000 ; PML4_ADDRESS
	xor eax, eax
	mov ecx, 4096 / 4
	rep_stosd

	mov edi, 0h31000 ; PDPT ADDRESS
	xor eax, eax
	mov ecx, 4096 / 4
	rep_stosd

	mov edi, 0h32000 ; PDT ADDRESS
	xor eax, eax
	mov ecx, 4096 / 4
	rep_stosd

	mov edi, 0h30000

	; mov cr3, edi
	du8 0h0F
	du8 0h22
	du8 0hDF

	;; Filling the tables
 	; mov [edi], PDPT_ADDRESS | ADDRESS_MAS | READABLE | PRESENT
	du8 0hC7
	du8 0h07
	du32 0h31000 | 1 | 2

	; mov edi, PDPT_ADDRESS
	mov edi, 0h31000

	; mov [edi], PDT_ADDRESS | ADDRESS_MASK | READABLE | PRESENT
	du8 0hC7
	du8 0h07
	du32 0h32000 | 1 | 2

	; mov edi, PDT_ADDRESS
	mov edi, 0h32000

	; mov ebx, READABLE | PRESENT | HUGE
	mov ebx, 1 | 2 | 0h80 
	mov ecx, 512

page_loop:
	; mov [edi], ebx
	du8 0h89
	du8 0h1F

	add ebx, 0h200000 ; 2 MB
	add edi, 8
	dec ecx
	jnz &page_loop

lmphase:
	;; Setup PAE
	; mov eax, cr4
	du8 0h0F
	du8 0h20
	du8 0hE0

	or eax, 0h20

	; mov cr4, eax
	du8 0h0F
	du8 0h22
	du8 0hE0

	;; Setup LM bit
	mov ecx, 0hC0000080
	rdmsr
	or eax, 0h100
	wrmsr

	;; Enable Paging
	; mov eax, cr0
	du8 0h0F
	du8 0h20
	du8 0hC0

	or eax, 0h80000000 | 1

	; mov cr0, eax
	du8 0h0F
	du8 0h22
	du8 0hC0

	; lgdt [GDT_DESC] 16 & 32
	du8 0h0F
	du8 0h01
	du8 0h15
	du32 GDT_DESC

	; jmp CODE_DESC:lmjump
	du8 0hEA
	du32 lmjump
	du16 GDT_CODE - GDT_START

lmjump:
	; mov ax, DATA_DESC
	du8 0hC7
	du8 0hC0
	du32 GDT_DATA - GDT_START

	; mov ds, ax
	du8 0h8E
	du8 0hD8

	; mov es, ax
	du8 0h8E
	du8 0hC0

	; mov fs, ax
	du8 0h8E
	du8 0hE0

	; mov gs, ax
	du8 0h8E
	du8 0hE8

	; mov ss, ax
	du8 0h8E
	du8 0hD0

	mov rsp, 0h90000
	mov rax, 0h100000

	jmp rax

	hlt
}

asm {
lmns:
	mov esi, lmnsmsg
	jmp &pmtorm
}

asm {
;; Drop to RealMode after an error occurs and output the message
;; stored at the address pointed by the si/esi/rsi register.
pmtorm:
	cli

	; lgdt [RGDT_DESC]
	du8 0h0F
    du8 0h01
	du8 0h15
	du32 RGDT_DESC

	; jmp (RGDT_CODE - RGDT_START):pmode16
	du8 0hEA
	du32 pmode16
	du16 RGDT_CODE - RGDT_START

pmode16:
	; mov ax, RGDT_DATA - RGDT_START
	du8 0hB8
	du16 RGDT_DATA - RGDT_START

	; mov ds, ax
	du8 0h8E
	du8 0hD8

	; mov es, ax
	du8 0h8E
	du8 0hC0

	; mov fs, ax
	du8 0h8E
	du8 0hE0

	; mov gs, ax
	du8 0h8E
	du8 0hE8

	; mov ss, ax
	du8 0h8E
	du8 0hD0

	;; Disable Paging
	; mov eax, cr0
	du8 0h0F
	du8 0h20
	du8 0hC0

	du8 0h66
	and eax, 0h7FFFFFFE

	; mov cr0, eax
	du8 0h0F
	du8 0h22
	du8 0hC0

	; jmp 0:rmode
	du8 0hEA
	du16 rmode
	du16 0

rmode:
	; xor ax, ax
	du8 0h31
	du8 0hC0

	; mov ds, ax
	du8 0h8E
	du8 0hD8

	; mov es, ax
	du8 0h8E
	du8 0hC0

	; mov fs, ax
	du8 0h8E
	du8 0hE0

	; mov gs, ax
	du8 0h8E
	du8 0hE8

	; mov ss, ax
	du8 0h8E
	du8 0hD0

	; mov sp, 0h7c00
	du8 0hBC
	du16 0h7c00

	; lidt [RIDT_DESC]
	du8 0h0F
    du8 0h01
	du8 0h1E
	du32 RIDT_DESC

	sti

	mov ah, 0h0e

print_loop:
	; mov al, [si]
	du8 0h8A
	du8 0h04

	cmp al, 0h00

	; jz &print_done
	du8 0h0F
	du8 0h84
	du16 &print_done

	int 0h10

	; inc si
	du8 0hFF
	du8 0hC6

	; jmp print_loop
	du8 0hE9
	du16 &print_loop

print_done:
	; jmp $
	du8 0hE9
	du16 0hFFFD
}

asm {
GDT_START:
	du64 0 ; Null
	GDT_CODE:
		du16 0hFFFF
		du16 0
		du8 0
		du8 0h9A
		du8 0hAF
		du8 9
	GDT_DATA:
		du16 0hFFFF
		du16 0
		du8 0
		du8 0h92
		du8 0hCF
		du8 0
GDT_END:
GDT_DESC:
	du16 GDT_END - GDT_START - 1
	du64 GDT_START
}

asm {
RGDT_START:
	du64 0 ; Null
	RGDT_CODE:
		du16 0hFFFF
		du16 0
		du8 0
		du8 0h9A
		du8 0
		du8 0
	RGDT_DATA:
		du16 0hFFFF
		du16 0
		du8 0
		du8 0h92
		du8 0
		du8 0
RGDT_END:
RGDT_DESC:
	du16 RGDT_END - RGDT_START - 1
	du32 RGDT_START

RIDT_DESC:
	du16 0h3FF
	du32 0
}

asm {
lmnsmsg: du8 "Boot failed! Long mode not supported!", 13, 10, 0
}