;;
;; Kitsune's Curse
;; Copyright (C) 2020-2023 Juan J. Martinez <jjm@usebox.net>
;;
;; This program is free software: you can redistribute it and/or modify
;; it under the terms of the GNU General Public License as published by
;; the Free Software Foundation, either version 3 of the License, or
;; (at your option) any later version.
;;
;; This program is distributed in the hope that it will be useful,
;; but WITHOUT ANY WARRANTY; without even the implied warranty of
;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
;; GNU General Public License for more details.
;;
;; You should have received a copy of the GNU General Public License
;; along with this program.  If not, see <https://www.gnu.org/licenses/>.
;;

.globl _wait
.globl _wait_for
.globl _wait_int6
.globl _setup_int
.globl _wait_vsync
.globl _wframes

.globl _pause_player
.globl _resume_player

.globl _reset_clock
.globl _get_clock

.globl _paused

MAX_CLOCK_BYTE = 0x0e

_wait::
        ld hl, #_tick

        ld a, (_wframes)
        ld c, a
wait_loop:
	ld a, (hl)
	cp c
	jr nc, wait_done
	halt
	jr wait_loop

wait_done:
	xor a
	ld (hl), a
        ret

_wait_for::
        ld b, l
wait_for_loop:
        call _wait
        djnz wait_for_loop
        ret

_wait_int6::
	ld a, (_int6)
	or a
	ret nz
	halt
	jr _wait_int6
        ret

_setup_int::
        ld a, l
        ld (_wframes), a

        xor a
        ld (_int6), a
        ld (_tick), a
        ld (paused_player), a

        ld (_paused), a
        call _reset_clock

	; sync
	call _wait_vsync
	halt
	halt
	call _wait_vsync

	di

	ld ix, #0x0038
	ld hl, #isr1
	ld (ix), #0xc3
	ld 1(ix), l
	ld 2(ix), h
	im 1

	ei
	ret

isr1:
        ex af,af
	push hl

	ld hl, #isr2
	ld (#0x39), hl

	; int6 ends
	xor a
	ld (_int6), a

        ld a, (paused_player)
        or a
        jr nz, player_is_paused

	push ix
	push iy
	push bc
	push de

	call _PLW_Play

	pop de
	pop bc
	pop iy
	pop ix

player_is_paused:
        pop hl
        ex af,af
	ei
	ret

isr2:
	exx
	ex af,af
	ld hl, #isr3
	ld (#0x39), hl
	exx
	ex af,af
	ei
	ret

isr3:
	exx
	ex af,af
	ld hl, #isr4
	ld (#0x39), hl
	ex af,af
	exx
	ei
	ret

isr4:
	exx
	ex af,af
	ld hl, #isr5
	ld (#0x39), hl

        ; update clock
        ld a, (_paused)
        or a
        jr nz, clock_is_paused
        ld a, (int_cnt)
        inc a
        cp #50
        jr nz, not_full_sec

        ld hl, (clock)
        ld a, h
        cp #(MAX_CLOCK_BYTE)
        jr nz, inc_clock
        cp l
        jr z, clock_limit

inc_clock:
        inc hl
        ld (clock), hl

clock_limit:
        xor a

not_full_sec:
        ld (int_cnt), a

clock_is_paused:
	ex af,af
	exx
	ei
	ret

isr5:
	exx
	ex af,af
	ld hl, #isr6
	ld (#0x39), hl

	; count a tick (50Hz)
	ld a, (_tick)
	inc a
	ld (_tick), a

	ex af,af
	exx
	ei
	ret

isr6:
	exx
	ex af,af
	ld hl, #isr1
	ld (#0x39), hl

	; int6 starts
	ld a, #1
	ld (_int6), a

	exx
	ex af,af
	ei
        ret

_pause_player::
        di
        ld a, #1
        ld (paused_player), a
        ei
        call _wait_int6
        jp _PLW_Stop

_resume_player::
        di
        xor a
        ld (paused_player), a
        ei
        ret

_reset_clock::
        di
        xor a
        ld (int_cnt), a
        ld (clock), a
        ld (clock + 1), a
        ei
        ret

_get_clock::
        ld hl, (clock)
        ret

_wframes:
        .ds 1

_int6:
        .ds 1
_tick:
        .ds 1

int_cnt:
        .ds 1
clock:
        .ds 2

paused_player:
        .ds 1