cpu 8086
bits 16

org 0x7c00

jmp 0:start
start:
	cld

	cli

	; Set up segments and stack
	mov ax, cs
	mov ds, ax
	mov es, ax
	mov ss, ax
	mov sp, $$

	sti

initialize_mouse:
	; Initialize mouse
	; https://www.ctyme.com/intr/rb-1601.htm
	mov ax, 0xc205
	mov bh, 3 ; TODO: This is the usual PS/2 mouse packet size, but is it correct here?
	int 0x15
	jc .error

	; Set handler address
	; https://www.ctyme.com/intr/rb-1603.htm
	mov ax, 0xc207
	; es is already set correctly
	mov bx, mouse_handler
	int 0x15
	jc .error

	; Enable mouse
	; https://www.ctyme.com/intr/rb-1596.htm
	mov ax, 0xc200
	mov bh, 1
	int 0x15
	jc .error

	jmp mainloop

	.error:
		; https://www.ctyme.com/intr/rb-1601.htm
		mov ax, 0xc201
		int 0x15
		jmp initialize_mouse

mainloop:
	; TODO: everything

hang:
	hlt
	;mov ax, 0x0e00 + '.'
	;int 0x10
	jmp hang

mouse_handler:
	push ax
	push bx
	push bp

	mov bp, sp

	; status
	mov bx, [bp+16]

	; X negative
	test bl, 0x10
	jz .no_x_negative
	mov ax, 0x0e00 + '-'
	int 0x10
	.no_x_negative:

	; X overflow
	test bl, 0x40
	jz .no_x_overflow
	mov ax, 0x0e00 + 'o'
	.no_x_overflow:

	; X
	mov ax, [bp+14]
	call hexprint8
	mov ax, 0x0e00 + ' '
	int 0x10

	; Y negative
	test bl, 0x20
	jz .no_y_negative
	mov ax, 0x0e00 + '-'
	int 0x10
	.no_y_negative:

	; Y overflow
	test bl, 0x80
	jz .no_y_overflow
	mov ax, 0x0e00 + 'o'
	.no_y_overflow:

	; Y
	mov ax, [bp+12]
	call hexprint8
	mov ax, 0x0e00 + ' '
	int 0x10

	; Left mouse
	test bl, 0x01
	jz .no_lmb
	mov ax, 0x0e00 + 'L'
	int 0x10
	.no_lmb:

	; Right mouse
	test bl, 0x02
	jz .no_rmb
	mov ax, 0x0e00 + 'R'
	int 0x10
	.no_rmb

	mov ax, 0x0e00 + 13
	int 0x10
	mov ax, 0x0e00 + 10
	int 0x10

	pop bp
	pop bx
	pop ax
	retf

hexprint16:
	xchg ah, al
	call hexprint8
	xchg ah, al

hexprint8:
	push ax
	push cx
	mov cl, 4
	shr al, cl
	call hexprint4
	pop cx
	pop ax

hexprint4:
	push ax
	and al, 0xf
	cmp al, 10
	jb .digit09

	add al, 'a' - '0' - 10

	.digit09:
	add al, '0'
	mov ah, 0x0e
	int 0x10
	pop ax
	ret

times 510-($-$$) db 0
db 0x55
db 0xaa