[bits 16]
[global ap_trampoline]
[global ap_trampoline_data]
[extern PML4]
[extern default_gdt]

%define to_target(addr) ((addr - ap_trampoline) + 0x8000)

ap_trampoline:
	cli
	cld

	mov eax, cr4
	or eax, 1 << 5 ; PAE
	mov cr4, eax

	mov eax, [to_target(ap_trampoline_data.pagetable)]
	mov cr3, eax

	mov ecx, 0xC0000080 ; EFER Model Specific Register
	rdmsr
	or eax, 1 << 8
	wrmsr

	mov eax, cr0
	or eax, 0x80000001 ; Paging, Protected Mode
	mov cr0, eax

	mov [to_target(ap_trampoline_data.status)], byte 10

	lgdt [to_target(gdt_descriptor)]

	;jmp $

	jmp codeseg:to_target(ap_trampoline_64)

 [bits 64]

 ap_trampoline_64:
 mov ax, 0x10
    mov ds, ax
    mov es, ax
    mov fs, ax
    mov gs, ax
    mov ss, ax

	mov [to_target(ap_trampoline_data.status)], byte 10

	jmp $

ap_trampoline_data:
	.status: db 0
	.pagetable: dq 0
	.stack_ptr: dq 0
	.entry: dq 0

gdt_nulldesc:
	dd 0
	dd 0
gdt_codedesc:
	dw 0xFFFF			; Limit
	dw 0x0000			; Base (low)
	db 0x00				; Base (medium)
	db 10101111b		; Flags
	db 11001111b		; Flags + Upper Limit
	db 0x00				; Base (high)
gdt_datadesc:
	dw 0xFFFF
	dw 0x0000
	db 0x00
	db 10101111b
	db 11001111b
	db 0x00

gdt_end:

gdt_descriptor:
	gdt_size:
		dw gdt_end - gdt_nulldesc - 1
		dq to_target(gdt_nulldesc)

codeseg equ gdt_codedesc - gdt_nulldesc


times 4096 - ($ - $$) db 0