.globl _ubox_read_ctl

RDPSG = 0x0096
WRTPSG = 0x0093
SNSMAT = 0x0141

_ubox_read_ctl::
	or a
	jr z, is_keyb
	dec a
	jr z, is_joy1
	dec a
	jr z, is_joy2

	xor a
	ret

is_joy2:
	; select
	ld e, #0xcf
	jr call_psg

is_joy1:
	; select
	ld e, #0x8f

call_psg:
	ld a, #0x0f
	call WRTPSG

	ld a, #0x0e

	di
	call RDPSG
	ei
	cpl
	and #0x3f
	ld e, a

	; button 2 (M)
	ld a, #4
	call SNSMAT
	rra
	rra
	rra
	ld a, #0x20
	jr nc, joy_extra_m
	xor a
joy_extra_m:
	or e
	ret

is_keyb:
	; button 2 (M)
	ld a, #4
	call SNSMAT
	rra
	rra
	rra
	ld e, #0x20
	jr nc, is_keyb_dir

	ld e, #0

is_keyb_dir:
	; direction
	ld a, #8
	call SNSMAT
	cpl
	rrca
	rrca
	ld c, a

	and #4
	ld b, a
	; b has left

	ld a, c
	rrca
	rrca
	ld c, a

	and #0x18
	or b
	ld b, a
	; added space and right

	ld a, c
	rrca
	and #3
	or b
	; added down and up

	or e
	; added 2nd fire (M)

	ret