; sample player
; need 317 tstates per sample

	org 32768
	
;	ld hl,22016	; start address of sample data
;	ld bc,221	; length of sample data, in bytes
;	push bc

start
;	call init_ay
;	ret
init_ay	
	ld a,7			; set bits 0-5 of AY register 7 so that all channels are fixed at 'high'
	ld bc,0xfffd	; output - this way the AY is not generating waveforms of its own, and
	out (c),a		; varying the volume (channels 8/9/10) creates our own wave output instead
	ld a,63
	ld b,0xbf
	out (c),a
;	ret
	
main_loop
	ld ix, 60000
	ld de, 17
	ld a, 00
	scf
	call 0x0556

	ld ix, 16384
	ld de, 6912
	ld a, 255
	scf
	call 0x0556
	
	ld b, 255
loppsa
	
	nop
	ld a,1
	nop
	ld a,1
	nop
	ld a,1
	nop
	ld a,1
	djnz loppsa
	
	di
	ld hl, 20672
	ld bc, 64
	call samplelp	; This call re-enables interrupts before returning

	ld hl, 20928
	ld bc, 64
	call samplelp	; This call re-enables interrupts before returning

	ld hl, 21184
	ld bc, 64
	call samplelp	; This call re-enables interrupts before returning

	ld hl, 21440
	ld bc, 29
	call samplelp	; This call re-enables interrupts before returning


;	ei
	jp main_loop
	ret


samplelp
	push bc		; 11

	; get low 4 bits to use as the first volume level
	ld a,(hl)	; 7
	and 0x0f	; 7

	; delay 117ish tstates
	ld b,8		; 7
zzz2	djnz zzz2
	
	; output that volume level to channels 8/9/10
	ld bc,0xfffd	; 10
	ld d,8		; 7
	out (c),d	; 12
	ld b,0xbf	; 7
	out (c),a	; 12
	inc d		; 4
	ld b,0xff	; 7
	out (c),d	; 12
	ld b,0xbf	; 7
	out (c),a	; 12
	inc d		; 4
	ld b,0xff	; 7
	out (c),d	; 12
	ld b,0xbf	; 7
	out (c),a	; 12
	
	; get the next volume level from the high 4 bits
	ld a,(hl)	; 7	; start tstate count here
	srl a		; 8
	srl a		; 8
	srl a		; 8
	srl a		; 8

	; delay 152ish tstates
	ld b,11		; 7 (orignally 11)
zzz1	djnz zzz1
				; 8

	; output that volume level to channels 8/9/10
	ld b,0xff	; 7
	ld d,8		; 7
	out (c),d	; 12
	ld b,0xbf	; 7
	out (c),a	; 12
	inc d		; 4
	ld b,0xff	; 7
	out (c),d	; 12
	ld b,0xbf	; 7
	out (c),a	; 12
	inc d		; 4
	ld b,0xff	; 7
	out (c),d	; 12
	ld b,0xbf	; 4
	out (c),a	; 12
	
	; move on to next byte
	inc hl		; 6
	
	; loop if we haven't reached the end of the sample
	pop bc		; 11
	dec bc		; 6
	ld a,b		; 4
	or c		; 4
	jr nz,samplelp	; 12

	ret