PAGE_SIZE = 0x1000

PAGE_PRESENT = (1 shl 0)
PAGE_WRITE   = (1 shl 1)

macro page_table_init_real pml4_table* {
	local page_table

	; zero out page table
	mov edi, pml4_table
	push di
	mov ecx, (PAGE_SIZE*4)/4
	xor eax, eax
	cld
	rep stosd
	pop di

	virtual at di
		label page_table
		.PML4T rb PAGE_SIZE
		.PDPT  rb PAGE_SIZE
		.PDT   rb PAGE_SIZE
		.PT    rb PAGE_SIZE
		.sizeof = $ - page_table
	end virtual

	; create first entry
	mov word [.PML4T], (pml4_table + .PDPT - page_table) or PAGE_PRESENT or PAGE_WRITE
	mov word [.PDPT],  (pml4_table + .PDT  - page_table) or PAGE_PRESENT or PAGE_WRITE
	mov word [.PDT],   (pml4_table + .PT   - page_table) or PAGE_PRESENT or PAGE_WRITE

	; identity map pages
	push di
	mov di, (pml4_table + .PT - page_table)
	mov ax, (PAGE_PRESENT or PAGE_WRITE)
@@:
	mov [di], eax
	add eax, PAGE_SIZE
	add di, 8
	cmp di, pml4_table + .sizeof
	jb @b

	pop di
}