;//_ parallel dac dds
;//_ stk500/atmega168p
;//_ 2007.11.6.01
;//_ by rmrubin@darkertechnologies.com

;//_ part file
.include "m164pdef.inc"

;//_ program constants

.equ sample_rate	=39				;500KHz @ 20MHz cpu clk = 39
.equ test_note		=28

.equ dac_port		=portb
.equ dac_ddr		=ddrb

;//_ register definitions
.def lpmin		=r0					;flash read data register

.def phase0		=r1					;32b phase accumulator
.def phase1		=r2
.def phase2		=r3
.def phase3		=r4

.def time0		=r5					;32b phase incriment 
.def time1		=r6
.def time2		=r7
.def time3		=r8

.def note		=r20				;midi note

.def point0		=r18				;flash pointer buffer
.def point1		=r19

.def temp		=r16				;working registers
.def temp2		=r17

;//_ interrupt vectors
.org $0
	jmp reset						;poweron/reset
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp sample_out					;ocr1a
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
	jmp stray_int
stray_int:
	reti

;//_ program init
reset:

	ldi temp,high(ramend) 			;stack setup
	ldi temp2,low(ramend)
	out sph,temp
	out spl,temp2

	clr temp						;sample timer setup
	sts tccr1a,temp
	ldi temp,0b00001001
	sts tccr1b,temp
	ldi temp,high(sample_rate)
	sts ocr1ah,temp
	ldi temp,low(sample_rate)
	sts ocr1al,temp
	ldi temp,(1<<ocie1a)
	sts timsk1,temp

	ser temp 						;dac port setup
	out dac_port,temp
	out dac_ddr,temp

;///DEBUG///	

	ldi note,test_note

	ldi point1,high(2*sine1024)
	ldi point0,low(2*sine1024)

;///DEBUG///

	clr phase0
	clr phase1
	clr phase2
	clr phase3

;//_ load new note and restart signal generator
change_note:
	ldi zh,high(2*miditab)			;load midi timing table flash pointer 
	ldi zl,low(2*miditab)
	
	mov temp,note					;multiply midi note value by 4
	clr temp2
	lsl temp
	rol temp2
	lsl temp
	rol temp2

	add zl,temp						;add adjusted midi note to flash pointer 
	adc zh,temp2					;and store the 32b time value in the
	lpm								;timex registers
	mov time3,lpmin

	adiw zh:zl,1					
	lpm
	mov time2,lpmin

	adiw zh:zl,1
	lpm
	mov time1,lpmin

	adiw zh:zl,1
	lpm
	mov time0,lpmin

	sei								;global interrupt enable

deathloop: rjmp deathloop			;main program wait loop

;//_ timed sample output loop
sample_out:

	mov temp,phase2					;store top word of phase accumulator
	mov temp2,phase3

	lsr temp2						;shift stored word right 6b
	ror temp
	lsr temp2
	ror temp
	lsr temp2
	ror temp
	lsr temp2
	ror temp
	lsr temp2
	ror temp
	lsr temp2
	ror temp

	mov zh,point1					;load wavetable start location
	mov zl,point0					;from buffer into z pointer

	add	zl,temp						;add shifted phase accumulator 
	adc	zh,temp2					;word to start location

	lpm								;load sample

	out dac_port,lpmin				;output sample
	
	add phase0,time0				;incriment phase accumulator
	adc phase1,time1
	adc phase2,time2
	adc phase3,time3

	reti							;exit sample output interrupt

;//_ midi note timing values
miditab:
.db $00,$01,$12,$56
.db $00,$01,$22,$A6
.db $00,$01,$33,$EE
.db $00,$01,$46,$3E
.db $00,$01,$59,$A4
.db $00,$01,$6E,$31
.db $00,$01,$83,$F8
.db $00,$01,$9B,$09
.db $00,$01,$B3,$7B
.db $00,$01,$CD,$60
.db $00,$01,$E8,$CF
.db $00,$02,$05,$E0
.db $00,$02,$24,$AB
.db $00,$02,$45,$4B
.db $00,$02,$67,$DC
.db $00,$02,$8C,$7B
.db $00,$02,$B3,$47
.db $00,$02,$DC,$62
.db $00,$03,$07,$EF
.db $00,$03,$36,$13
.db $00,$03,$66,$F5
.db $00,$03,$9A,$BF
.db $00,$03,$D1,$9E
.db $00,$04,$0B,$C0
.db $00,$04,$49,$56
.db $00,$04,$8A,$97
.db $00,$04,$CF,$B8
.db $00,$05,$18,$F6
.db $00,$05,$66,$8F
.db $00,$05,$B8,$C5
.db $00,$06,$0F,$DE
.db $00,$06,$6C,$26
.db $00,$06,$CD,$EA
.db $00,$07,$35,$7E
.db $00,$07,$A3,$3C
.db $00,$08,$17,$7F
.db $00,$08,$92,$AD
.db $00,$09,$15,$2D
.db $00,$09,$9F,$70
.db $00,$0A,$31,$EC
.db $00,$0A,$CD,$1E
.db $00,$0B,$71,$8A
.db $00,$0C,$1F,$BD
.db $00,$0C,$D8,$4C
.db $00,$0D,$9B,$D4
.db $00,$0E,$6A,$FD
.db $00,$0F,$46,$77
.db $00,$10,$2E,$FE
.db $00,$11,$25,$59
.db $00,$12,$2A,$5A
.db $00,$13,$3E,$E1
.db $00,$14,$63,$D8
.db $00,$15,$9A,$3C
.db $00,$16,$E3,$14
.db $00,$18,$3F,$7A
.db $00,$19,$B0,$98
.db $00,$1B,$37,$A8
.db $00,$1C,$D5,$FA
.db $00,$1E,$8C,$EE
.db $00,$20,$5D,$FD
.db $00,$22,$4A,$B2
.db $00,$24,$54,$B5
.db $00,$26,$7D,$C1
.db $00,$28,$C7,$B0
.db $00,$2B,$34,$77
.db $00,$2D,$C6,$28
.db $00,$30,$7E,$F4
.db $00,$33,$61,$2F
.db $00,$36,$6F,$50
.db $00,$39,$AB,$F3
.db $00,$3D,$19,$DC
.db $00,$40,$BB,$F9
.db $00,$44,$95,$65
.db $00,$48,$A9,$69
.db $00,$4C,$FB,$82
.db $00,$51,$8F,$61
.db $00,$56,$68,$EE
.db $00,$5B,$8C,$4F
.db $00,$60,$FD,$E8
.db $00,$66,$C2,$5E
.db $00,$6C,$DE,$A0
.db $00,$73,$57,$E6
.db $00,$7A,$33,$B8
.db $00,$81,$77,$F3
.db $00,$89,$2A,$CA
.db $00,$91,$52,$D3
.db $00,$99,$F7,$05
.db $00,$A3,$1E,$C2
.db $00,$AC,$D1,$DD
.db $00,$B7,$18,$9F
.db $00,$C1,$FB,$D0
.db $00,$CD,$84,$BD
.db $00,$D9,$BD,$41
.db $00,$E6,$AF,$CD
.db $00,$F4,$67,$71
.db $01,$02,$EF,$E5
.db $01,$12,$55,$94
.db $01,$22,$A5,$A5
.db $01,$33,$EE,$09
.db $01,$46,$3D,$84
.db $01,$59,$A3,$B9
.db $01,$6E,$31,$3D
.db $01,$83,$F7,$9F
.db $01,$9B,$09,$79
.db $01,$B3,$7A,$82
.db $01,$CD,$5F,$9A
.db $01,$E8,$CE,$E2
.db $02,$05,$DF,$CA
.db $02,$24,$AB,$28
.db $02,$45,$4B,$4B
.db $02,$67,$DC,$12
.db $02,$8C,$7B,$07
.db $02,$B3,$47,$72
.db $02,$DC,$62,$7B
.db $03,$07,$EF,$3E
.db $03,$36,$12,$F2
.db $03,$66,$F5,$03
.db $03,$9A,$BF,$34
.db $03,$D1,$9D,$C4
.db $04,$0B,$BF,$94
.db $04,$49,$56,$50
.db $04,$8A,$96,$95
.db $04,$CF,$B8,$25
.db $05,$18,$F6,$0E
.db $05,$66,$8E,$E5
.db $05,$B8,$C4,$F5
.db $06,$0F,$DE,$7C
.db $06,$6C,$25,$E5
.db $06,$CD,$EA,$06
.db $07,$35,$7E,$67
.db $07,$A3,$3B,$87
.db $08,$17,$7F,$28
.db $08,$92,$AC,$A0
.db $09,$15,$2D,$2B
.db $09,$9F,$70,$49
.db $0A,$31,$EC,$1C
.db $0A,$CD,$1D,$CA
.db $0B,$71,$89,$EB
.db $0C,$1F,$BC,$F9
.db $0C,$D8,$4B,$CA
.db $0D,$9B,$D4,$0C
.db $0E,$6A,$FC,$CE
.db $0F,$46,$77,$0E
.db $10,$2E,$FE,$50
.db $11,$25,$59,$3F

;//_ 1024*8b sample wavetables 

sine1024:
.db 128,129,130,131,131,132,133,134,135,135,136,137,138,138,139,140,141,142,142,143
.db 144,145,145,146,147,148,149,149,150,151,152,152,153,154,155,155,156,157,158,158
.db 159,160,161,162,162,163,164,165,165,166,167,167,168,169,170,170,171,172,173,173
.db 174,175,176,176,177,178,178,179,180,181,181,182,183,183,184,185,186,186,187,188
.db 188,189,190,190,191,192,192,193,194,194,195,196,196,197,198,198,199,200,200,201
.db 202,202,203,203,204,205,205,206,207,207,208,208,209,210,210,211,211,212,213,213
.db 214,214,215,215,216,217,217,218,218,219,219,220,220,221,221,222,222,223,224,224
.db 225,225,226,226,227,227,228,228,228,229,229,230,230,231,231,232,232,233,233,234
.db 234,234,235,235,236,236,236,237,237,238,238,238,239,239,240,240,240,241,241,241
.db 242,242,242,243,243,243,244,244,244,245,245,245,246,246,246,246,247,247,247,248
.db 248,248,248,249,249,249,249,250,250,250,250,250,251,251,251,251,251,252,252,252
.db 252,252,252,253,253,253,253,253,253,253,254,254,254,254,254,254,254,254,254,254
.db 254,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255,255
.db 255,255,255,255,255,255,255,255,255,255,254,254,254,254,254,254,254,254,254,254
.db 254,253,253,253,253,253,253,253,252,252,252,252,252,252,251,251,251,251,251,250
.db 250,250,250,250,249,249,249,249,248,248,248,248,247,247,247,246,246,246,246,245
.db 245,245,244,244,244,243,243,243,242,242,242,241,241,241,240,240,240,239,239,238
.db 238,238,237,237,236,236,236,235,235,234,234,234,233,233,232,232,231,231,230,230
.db 229,229,228,228,228,227,227,226,226,225,225,224,224,223,222,222,221,221,220,220
.db 219,219,218,218,217,217,216,215,215,214,214,213,213,212,211,211,210,210,209,208
.db 208,207,207,206,205,205,204,203,203,202,202,201,200,200,199,198,198,197,196,196
.db 195,194,194,193,192,192,191,190,190,189,188,188,187,186,186,185,184,183,183,182
.db 181,181,180,179,178,178,177,176,176,175,174,173,173,172,171,170,170,169,168,167
.db 167,166,165,165,164,163,162,162,161,160,159,158,158,157,156,155,155,154,153,152
.db 152,151,150,149,149,148,147,146,145,145,144,143,142,142,141,140,139,138,138,137
.db 136,135,135,134,133,132,131,131,130,129,128,128,127,126,125,124,124,123,122,121
.db 120,120,119,118,117,117,116,115,114,113,113,112,111,110,110,109,108,107,106,106
.db 105,104,103,103,102,101,100,100, 99, 98, 97, 97, 96, 95, 94, 93, 93, 92, 91, 90
.db  90, 89, 88, 88, 87, 86, 85, 85, 84, 83, 82, 82, 81, 80, 79, 79, 78, 77, 77, 76
.db  75, 74, 74, 73, 72, 72, 71, 70, 69, 69, 68, 67, 67, 66, 65, 65, 64, 63, 63, 62
.db  61, 61, 60, 59, 59, 58, 57, 57, 56, 55, 55, 54, 53, 53, 52, 52, 51, 50, 50, 49
.db  48, 48, 47, 47, 46, 45, 45, 44, 44, 43, 42, 42, 41, 41, 40, 40, 39, 38, 38, 37
.db  37, 36, 36, 35, 35, 34, 34, 33, 33, 32, 31, 31, 30, 30, 29, 29, 28, 28, 27, 27
.db  27, 26, 26, 25, 25, 24, 24, 23, 23, 22, 22, 21, 21, 21, 20, 20, 19, 19, 19, 18
.db  18, 17, 17, 17, 16, 16, 15, 15, 15, 14, 14, 14, 13, 13, 13, 12, 12, 12, 11, 11
.db  11, 10, 10, 10,  9,  9,  9,  9,  8,  8,  8,  7,  7,  7,  7,  6,  6,  6,  6,  5
.db   5,  5,  5,  5,  4,  4,  4,  4,  4,  3,  3,  3,  3,  3,  3,  2,  2,  2,  2,  2
.db   2,  2,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  0,  0,  0,  0,  0,  0,  0
.db   0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0,  0
.db   0,  0,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  1,  2,  2,  2,  2,  2,  2,  2
.db   3,  3,  3,  3,  3,  3,  4,  4,  4,  4,  4,  5,  5,  5,  5,  5,  6,  6,  6,  6
.db   7,  7,  7,  7,  8,  8,  8,  9,  9,  9,  9, 10, 10, 10, 11, 11, 11, 12, 12, 12
.db  13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 17, 17, 17, 18, 18, 19, 19, 19, 20
.db  20, 21, 21, 21, 22, 22, 23, 23, 24, 24, 25, 25, 26, 26, 27, 27, 27, 28, 28, 29
.db  29, 30, 30, 31, 31, 32, 33, 33, 34, 34, 35, 35, 36, 36, 37, 37, 38, 38, 39, 40
.db  40, 41, 41, 42, 42, 43, 44, 44, 45, 45, 46, 47, 47, 48, 48, 49, 50, 50, 51, 52
.db  52, 53, 53, 54, 55, 55, 56, 57, 57, 58, 59, 59, 60, 61, 61, 62, 63, 63, 64, 65
.db  65, 66, 67, 67, 68, 69, 69, 70, 71, 72, 72, 73, 74, 74, 75, 76, 77, 77, 78, 79
.db  79, 80, 81, 82, 82, 83, 84, 85, 85, 86, 87, 88, 88, 89, 90, 90, 91, 92, 93, 93
.db  94, 95, 96, 97, 97, 98, 99,100,100,101,102,103,103,104,105,106,106,107,108,109
.db 110,110,111,112,113,113,114,115,116,117,117,118,119,120,120,121,122,123,124,124
.db 125,126,127,128