===== TinyMidi Source Code: =====


<code>
;---------------------------------------------
;TinyMIDI (c) GRG/SHAPE 2007
;---------------------------------------------
;This program was made for the Sequential (SCI) Interface.
;It will play the notes you press on your midi keyboard
;with the sid chip. 

_MIDIReset      = %00000011 ;Same for all interfaces
_MIDI16CountDiv = %00010101 ;1mhz interfaces: 16 divider
_MIDI64CountDIv = %00010110 ;2mhz interfaces: 64 divider
_IRQMIDI16      = %10010101 ;1mhz interfaces: IRQ enabled
_IRQMIDI64      = %10010110 ;2mhz interfaces: IRQ enabled

;Sequential registers
MIDI_ControlReg = $de00
MIDI_StatusReg  = $de02
MIDI_Tx         = $de01
MIDI_Rx         = $de03

;Adjust hardrestart to 2 for Attack Values 1-F.
HARDRESTART	= 1		;1 or 2

buffnotes	= $2000		;All MIDI notes are buffered here

		* = $0801
		.byte $0b,$08,$d7,$07
		.byte $9e
		.text "2061"
		.byte 0,0,0

		lda #<message
		ldy #>message
		jsr $ab1e
		sei
		lda #$35
		sta $01
		lda #$03
		sta MIDI_ControlReg   ;Reset Midi interface
		lda #$95
		sta MIDI_ControlReg   ;Enable Midi IRQ & Clock 16
		jsr init_soundplayer
		lda #<hwirq
		sta $0314
		lda #>hwirq
		sta $0315
		lda #<irq
		sta $fffe
		lda #>irq
		sta $ffff
		lda #<nmi
		sta $fffa
		sta $0318
		lda #>nmi
		sta $fffb
		sta $0319
		lda #$01              ;Irq on
		sta $d01a
		lda #$fb
		sta $d012
		lda $d011
		and #$7f
		sta $d011
		lda #$7f
		sta $dc0d
		bit $dc0d
		cli
keyloop		inc $01               ;36
		jsr $ffe4
		dec $01               ;35
		cmp #0
		beq keyloop
		jmp keyloop
                
midinote	.byte 0 ;0-127
ncount		.byte 0 ;max 127 (max keys on keyboard)
countby		.byte 0 ;count bytes in buffer (0-255)
mibcount	.byte 0	;Midi byte count (0-255)

;---------------------------------------------------
*= (*+$ff)&$ff00 ;Start the following code on a page
;---------------------------------------------------
;MIDI IRQ:
i80_noteoff1	sta midinote
		lda #<i80_noteoff2
		jmp setexirq
i80_noteoff2	ldx mibcount
		lda midinote
		ora #$80
		sta buffnotes,x
		inc mibcount
		inc ncount
		lda #<i80_noteoff1
		jmp setexirq

i90_noteon1	sta midinote
		lda #<i90_noteon2
		jmp setexirq
i90_noteon2	beq i90_noteoff
		lda #0
		.byte $2c
i90_noteoff	lda #$80
		ldx mibcount
		ora midinote
		sta buffnotes,x
		inc mibcount
		inc ncount
		lda #<i90_noteon2
		jmp setexirq

;-------- Unused routines here
iC0_programchange1
iA0_aftertouch1
iD0_channelpress1
iB0_cwheel1
iE0_cwheel1
		lda #<exirq
		jmp setexirq
                
;------- STATUS fetch

get_statb	and #$f0              ;Allow all Midi channels
		cmp #$e0
		beq stpwheel
		cmp #$b0
		beq stcwheel
		cmp #$90
		beq stnoteon
		cmp #$80
		beq stnoteoff
		cmp #$d0
		beq stchpress
		cmp #$a0
		beq statouch
		cmp #$c0
		beq stprchange
		lda #<exirq
		.byte $2c
stprchange	lda #<iC0_programchange1
		.byte $2c
statouch	lda #<iA0_aftertouch1
		.byte $2c
stchpress	lda #<iD0_channelpress1
		.byte $2c
stnoteoff	lda #<i80_noteoff1
		.byte $2c
stnoteon	lda #<i90_noteon1
		.byte $2c
stcwheel	lda #<iB0_cwheel1
		.byte $2c
stpwheel	lda #<iE0_cwheel1
setexirq	sta mjump+1
exirq		lda #0
		sta $d020
		pla
		tay
		pla
		tax
		pla
		rti

irmid		pha
		txa
		pha
		tya
		pha
hwirmid		dec $d020
		lda MIDI_StatusReg
		bpl exirq          ;0-7f
		;bit parity        ;$70
		;beq parok
		;jmp error
parok		and #%00000001
		beq error
setMidi_Rx	lda MIDI_Rx
		bmi get_statb
mjump		jmp exirq
error		inc $d021          ;endless error
		jmp error

parity		.byte %01110000 ;parity error,receiver overrun,framing error

irq		bit $d019	;FFFE/FFFF IRQ
		bpl irmid	;Check if MIDI made this irq
		pha
		txa
		pha
		tya
		pha
		jmp d019clear
hwirq		bit $d019	;0314/0315 IRQ
		bpl hwirmid	;Check if MIDI made this irq
d019clear	lda #1
		sta $d019
		cli		;Make sure more Midi irq's can happen
		lda #5
		sta $d020
		jsr sound_init
		jsr sound_play
		lda #0
		sta $d020
		lda $01
		pha
		lda #$37
		sta $01
		jsr $ea87        ;C64 Keyboard scan
		lda $dc0d
		pla
		sta $01
		pla
		tay
		pla
		tax
		pla
nmi		rti

;---------------------

sound_init	sei             ;Must set SEI -  midi irq must not interrupt this part.
				;Quickly copy data you need into the sound player data
				;if this routine is slow you will loose midi data
sinit		lda ncount	;More bytes left in buffer ?
		beq nonote
		ldy countby
		lda buffnotes,y
		bmi noteoff1
keyset		jsr set_concate
		inc countby
		dec ncount
		jmp sinit
noteoff1	and #$7f
keyclear	jsr clear_concate
		inc countby
		dec ncount
		jmp sinit
nonote		cli		;CLI - MIDI irq can now occur again
		rts


set_concate	ldx chan		;Concate
		sta note,x
		lda #HARDRESTART	;1or2
		sta hreset,x
		inx
		cpx #3
		bne rer
		ldx #0
rer		stx chan
		rts

clear_concate	sta tempnot2+1
		ldx #2
tempnot2	lda #0
		cmp note,x
		bne found2
		lda #$fe
		sta gate,x		;Gate off
		sta hreset,x
found2		dex
		bpl tempnot2
		rts

;--------- Reset buffer counters and sid chip

init_soundplayer			
		lda #0
		sta ncount
		sta countby
		sta mibcount
		ldx #$17
ressid		sta $d400,x
		dex
		bpl ressid
		rts

;---------- 3 voice music player
;TinySDI Player (c) GRG/SHAPE 2007

sound_play	ldx #2
mloop		stx savx+1
		ldy sidvoice,x
		lda hreset,x
		bmi next_sid		;FF
		pha
		cmp #HARDRESTART	;1or2
		bne nn
		lda #1
		sta $d406,y		;ADSR high
		lda #$0f
		sta $d405,y
		lda #$fe
		sta gate,x		;Gate off
nn		dec hreset,x
		pla
		bne next_sid
		lda #$ff
		sta gate,x
		sta hreset,x
		lda note,x
		sta note2,x
		lda #$01
		sta $d405,y		;AD
		lda #$da
		sta $d406,y		;SR
next_sid	lda note2,x
		tax
		lda freqlo,x
		sta $d400,y
		lda freqhi,x
		sta $d401,y
		ldx savx+1
		lda #$21
		and gate,x
		sta $d404,y
savx		ldx #0
		dex
		bpl mloop
		lda #$0f
		sta $d418
		rts

chan     .byte 0
note     .byte 0,0,0
note2    .byte 0,0,0
hreset   .byte $ff,$ff,$ff
gate     .byte $fe,$fe,$fe
sidvoice .byte 0,7,14

;PAL tuned frequence table:
freqlo   .byte $16,$27,$39,$4b,$5f,$74
         .byte $8a,$a1,$ba,$d4,$f0,$0e
         .byte $2d,$4e,$71,$96,$be,$e7
         .byte $14,$42,$74,$a9,$e0,$1b
         .byte $5a,$9c,$e2,$2d,$7b,$cf
         .byte $27,$85,$e8,$51,$c1,$37
         .byte $b4,$38,$c4,$59,$f7,$9d
         .byte $4e,$0a,$d0,$a2,$81,$6d
         .byte $67,$70,$89,$b2,$ed,$3b
         .byte $9c,$13,$a0,$45,$02,$da
         .byte $ce,$e0,$11,$64,$da,$76
         .byte $39,$26,$40,$89,$04,$b4
         .byte $9c,$c0,$23,$c8,$b4,$eb
         .byte $72,$4c,$80,$12,$08,$68
         .byte $39,$80,$45,$90,$68,$d6
         .byte $e3,$99,$00,$24,$10,$ff
freqhi   .byte $01,$01,$01,$01,$01,$01
         .byte $01,$01,$01,$01,$01,$02
         .byte $02,$02,$02,$02,$02,$02
         .byte $03,$03,$03,$03,$03,$04
         .byte $04,$04,$04,$05,$05,$05
         .byte $06,$06,$06,$07,$07,$08
         .byte $08,$09,$09,$0a,$0a,$0b
         .byte $0c,$0d,$0d,$0e,$0f,$10
         .byte $11,$12,$13,$14,$15,$17
         .byte $18,$1a,$1b,$1d,$1f,$20
         .byte $22,$24,$27,$29,$2b,$2e
         .byte $31,$34,$37,$3a,$3e,$41
         .byte $45,$49,$4e,$52,$57,$5c
         .byte $62,$68,$6e,$75,$7c,$83
         .byte $8b,$93,$9c,$a5,$af,$b9
         .byte $c4,$d0,$dd,$ea,$f8,$ff

message	.byte $93,$05
	.text "tinymidi by grg/shape"
	.byte 0
</code>