;************************************************************
;
; Piano83 v2.0
; ============
; for Ion on the TI-83/TI-83+
;
; by badja
; 5 March 2000
;
; http://move.to/badja
; badja@alphalink.com.au
;
; You may modify this source code for personal use only.
; You may NOT distribute the modified source or program file.
;
;************************************************************

.NOLIST
#include "ion.inc"
.LIST


tuning	.equ	saferam1

ch1count	.equ	saferam1+2
ch1freq	.equ	saferam1+4
ch1curr	.equ	saferam1+6

ch2count	.equ	saferam1+7
ch2freq	.equ	saferam1+9
ch2curr	.equ	saferam1+11

flags		.equ	asm_flag1
key		.equ	asm_flag1_0
chord		.equ	asm_flag1_1


#ifdef TI83P
	.org	progstart-2
	.db	$BB,$6D
#else
	.org	progstart
#endif
	xor	a
	jr	nc,start
	.db	"Piano83 2.0",0

start:
	ld	hl,54			; initial tuning
	ld	(tuning),hl
	res	key,(iy+flags)	; initial key
	res	chord,(iy+flags)	; initial chord mode
	res	appAutoScroll,(iy+appFlags)
	ld	hl,$0000		; show instructions
	ld	(CURROW),hl
	ld	hl,instructions
	ld	b,6
putInstr:
	set	textinverse,(iy+textflags)
	bcall(_puts)
	res	textinverse,(iy+textflags)
	bcall(_puts)
	djnz	putInstr
	call	dispMaj
	call	dispTune
	call	dispUnison

mainLoop:
	ld	e,0		; E = number of notes pressed
	ld	h,e		; initialise channels to 0 (no note)
	ld	l,e
	ld	(ch1freq),hl
	ld	(ch2freq),hl

	ld	d,$bf		; D = key column
	call	getKeyData
	ld	hl,0		; true pitch octaves
	ld	bc,24
	bit	4,a
	jp	z,octave1
	bit	3,a
	jp	z,octave2
	bit	2,a
	jp	z,octave3
	bit	1,a
	jp	z,octave4

	bit	5,a		; check if 2nd is pressed
	jr	nz,not2nd
	ld	bc,2
	push	af
	call	storeNote
	pop	af
not2nd:

	bit	key,(iy+flags)	; determine major/minor
	jr	z,useMajKey
	ld	hl,keyMapMin	; load minor keymap

	bit	6,a			; if minor, check if MODE is pressed
	jr	nz,notMODE
	ld	bc,0
	push	af
	call	storeNote
	pop	af
notMODE:
	jr	useMinKey

useMajKey:
	ld	hl,keyMapMaj	; load major keymap

useMinKey:
	bit	7,a			; check if DEL is pressed
	jr	nz,notDEL
	ld	bc,26
	call	storeNote
notDEL:

nextCol:
	call	getKeyData
	ld	b,8		; check all 8 keys in key column
checkCol:
	push	bc
	rla			; get next bit from A
	jr	c,noPlay	; if bit is 1, key is not pressed
	push	af
	ld	a,(hl)	; get note from keymap
	cp	255		; 255 in the key map means no sound
	jr	z,noSound
	ld	b,0		; store/play the note
	ld	c,a
	call	storeNote
noSound:
	pop	af
noPlay:
	inc	hl
	pop	bc
	djnz	checkCol
	ld	a,d
	cp	$fd		; continue until key column is $fd
	jr	nz,nextCol

	call	getKeyData
	cp	191		; check if CLEAR is pressed
	jr	z,exit
	push	de
	cp	223
	call	z,changeChord
	cp	251
	call	z,downOct
	cp	253
	call	z,upOct
	pop	de

	call	getKeyData
	bit	1,a		; check if left is pressed
	jr	nz,notLeft
	ld	bc,28
	call	storeNote
notLeft:
	bit	0,a
	push	af
	call	z,down
	pop	af
	bit	2,a
	push	af
	call	z,changeKey
	pop	af
	bit	3,a
	call	z,up

	in	a,(3)		; check if ON is pressed
	bit	3,a
	jr	nz,notOn
	ld	bc,30
	call	storeNote
notOn:

	bit	chord,(iy+flags)	; if in unison mode, play the two channels
	call	z,playNotes
	jp	mainLoop


exit:
	set	appAutoScroll,(iy+appFlags)
	ret


storeNote:
	bit	1,e			; maximum of two notes at a time in unison mode
	ret	nz
	push	hl
	ld	hl,pitches		; address of the pitches table
	add	hl,bc			; add the pitch
	ld	bc,(tuning)
	add	hl,bc			; add the tuning
	ld	c,(hl)		; get the period in BC
	inc	hl
	ld	b,(hl)
	bit	chord,(iy+flags)	; jump if in arpeggio mode
	jr	nz,arpeggio
	bit	0,e			; store note into next channel
	call	z,storeCh1
	call	nz,storeCh2
	inc	e			; move to next channel
	jr	doneNote
arpeggio:
	call	storeCh1		; store into both channels
	call	storeCh2
	call	playNotes		; play note immediately
doneNote:
	pop	hl
	ret


storeCh1:
	ld	(ch1freq),bc
	ret

storeCh2:
	ld	(ch2freq),bc
	ret


octave4:
	add	hl,bc
octave3:
	add	hl,bc
octave2:
	add	hl,bc
octave1:
	bit	key,(iy+flags)
	jr	nz,isMinKey
	ld	bc,6
	add	hl,bc
isMinKey:
	ld	(tuning),hl
	call	dispTune
	call	delay
	jp	mainLoop


dispTune:
	ld	hl,$0b03
	ld	(CURROW),hl
	ld	hl,(tuning)
	sra	l
	bcall(_dispHL)
	ld	bc,$0803
	ld	hl,txtTune
	jr	putString


dispMaj:
	ld	bc,$0b02
	ld	hl,txtMajor
	jr	putString

dispMin:
	ld	bc,$0b02
	ld	hl,txtMinor


putString:
	ld	(CURROW),bc
	bcall(_puts)
	ret


changeKey:
	bit	key,(iy+flags)
	jr	nz,toMajor
	set	key,(iy+flags)
	call	dispMin
	jr	delay
toMajor:
	res	key,(iy+flags)
	call	dispMaj
	jr	delay


changeChord:
	ld	a,(iy+flags)
	xor	%00000010
	ld	(iy+flags),a

dispChord:
	bit	chord,(iy+flags)
	jr	z,dispUnison

dispArpeggio:
	ld	bc,$0907
	ld	hl,txtArpeggio
	call	putString
	jr	delay

dispUnison:
	ld	bc,$0907
	ld	hl,txtUnison
	call	putString
	jr	delay


downOct:
	ld	a,(tuning)
	cp	24
	ret	c
	sub	24
	jr	donetune

upOct:
	ld	a,(tuning)
	cp	62
	ret	nc
	add	a,24
	jr	doneTune

down:
	ld	a,(tuning)
	cp	84
	ret	z
	add	a,2
	jr	doneTune

up:
	ld	a,(tuning)
	cp	0
	ret	z
	sub	2
doneTune:
	ld	(tuning),a
	call	dispTune


delay:
	ld	bc,$8000
delayLoop:
	dec	bc
	ld	a,b
	or	c
	jr	nz,delayLoop
	ret


getKeyData:
	ld	a,$ff		; reset keyport
	out	(1),a
	ld	a,d
	out	(1),a
	in	a,(1)
	sra	d		; D = next key column
	ret


playNotes:
	ld	b,0		; loop 256 times
playLoop:
	push	bc

	ld	hl,(ch1count)
	dec	h			; decrease MSB of count
	jr	nz,noEdge1a		; jump if not zero (on edge of square wave when count reaches 0)
	ld	bc,(ch1freq)	; BC = freq
	ld	a,b
	or	a
	jr	z,noEdge1b		; skip if MSB is 0 (no note)
	add	hl,bc			; otherwise add frequency to count
	ld	bc,ch1curr		; and
	ld	a,(bc)		; invert bit 0 of curr
	xor	1			; 0->1 or 1->0
	ld	(bc),a
	jr	noEdge1c

noEdge1a:				; makes the playNotes routine constant time ...
	res	7,(ix)	; 23
	bit	7,(hl)	; 12
				;=35
noEdge1b:				; ... for greater pitch accuracy
	res	7,(ix)	; 23
	adc	a,(ix)	; 19
	adc	a,(hl)	;  7
				;=49
noEdge1c:
	ld	(ch1count),hl

	ld	hl,(ch2count)
	dec	h			; decrease MSB of count
	jr	nz,noEdge2a		; jump if not zero (on edge of square wave when count reaches 0)
	ld	bc,(ch2freq)	; BC = freq
	ld	a,b
	or	a
	jr	z,noEdge2b		; skip if MSB is 0 (no note)
	add	hl,bc			; otherwise add frequency to count
	ld	bc,ch2curr		; and
	ld	a,(bc)		; invert bit 0 of curr
	xor	1			; 0->1 or 1->0
	ld	(bc),a
	jr	noEdge2c

noEdge2a:				; makes the playNotes routine constant time ...
	res	7,(ix)	; 23
	bit	7,(hl)	; 12
				;=35
noEdge2b:				; ... for greater pitch accuracy
	res	7,(ix)	; 23
	adc	a,(ix)	; 19
	adc	a,(hl)	;  7
				;=49
noEdge2c:
	ld	(ch2count),hl

	ld	a,(ch1curr)
	ld	b,a
	ld	a,(ch2curr)
	ld	c,a

	ld	a,%00110100
	srl	b			; rotate channel 1 bit into A
	rla
	srl	c			; rotate channel 2 bit into A
	rla
	out	(0),a			; output the sample

	pop	bc
	djnz	playLoop

	ret


keyMapMaj:
	.db	6,10,12,16,20,24,26,255
	.db	4,8,255,14,18,22,255,28
	.db	30,34,36,40,44,48,50,54
	.db	255,32,255,38,42,46,255,52

keyMapMin:
	.db	6,8,12,16,18,22,26,255
	.db	4,255,10,14,255,20,24,28
	.db	30,32,36,40,42,46,50,54
	.db	255,255,34,38,255,44,48,52

pitches:
	; lowest note: G# 1
	; highest note: F 7
	.dw	$898C
	.dw	$81D4
	.dw	$7A8A
	.dw	$73AA
	.dw	$6D2C
	.dw	$670B
	.dw	$6143
	.dw	$5BCD
	.dw	$56A6
	.dw	$51C9
	.dw	$4D32
	.dw	$48DD
	.dw	$44C6
	.dw	$40EA
	.dw	$3D45
	.dw	$39D5
	.dw	$3696
	.dw	$3385
	.dw	$30A1
	.dw	$2DE6
	.dw	$2B53
	.dw	$28E4
	.dw	$2699
	.dw	$246E
	.dw	$2263
	.dw	$2075
	.dw	$1EA2
	.dw	$1CEA
	.dw	$1B4B
	.dw	$19C2
	.dw	$1850
	.dw	$16F3
	.dw	$15A9
	.dw	$1472
	.dw	$134C
	.dw	$1237
	.dw	$1131
	.dw	$103A
	.dw	$0F51
	.dw	$0E75
	.dw	$0DA5
	.dw	$0CE1
	.dw	$0C28
	.dw	$0B79
	.dw	$0AD4
	.dw	$0A39
	.dw	$09A6
	.dw	$091B
	.dw	$0898
	.dw	$081D
	.dw	$07A8
	.dw	$073A
	.dw	$06D2
	.dw	$0670
	.dw	$0614
	.dw	$05BC
	.dw	$056A
	.dw	$051C
	.dw	$04D3
	.dw	$048D
	.dw	$044C
	.dw	$040E
	.dw	$03D4
	.dw	$039D
	.dw	$0369
	.dw	$0338
	.dw	$030A
	.dw	$02DE
	.dw	$02B5
	.dw	$028E


instructions:
	.db	" Piano83 ",0,"http://"
	.db	"   move.to/badja",0
	.db	"Right",0," Key:      ",0
	.db	"Up/Down",0,"         ",0
	.db	"+/-",0," Tune by 8ves",0
	.db	"Y/WIN/ZOOM/TRACE",0
	.db	" True-pitch 8ves",0
	.db	"^",0," Chord:",0

txtMajor:
	.db	"C Maj",0

txtMinor:
	.db	"A Min",0

txtTune:
	.db	"Tune:",0

txtUnison:
	.db	"Unison ",0

txtArpeggio:
	.db	"Arpegio",0

.end