View difference between Paste ID: LU4TY8cY and pHw97DkU

 .define NOTE_C 262
 .define NOTE_Cs 277
 .define NOTE_D 294
 .define NOTE_Ds 311
 .define NOTE_E 330
 .define NOTE_F 349
 .define NOTE_Fs 370
 .define NOTE_G 392
 .define NOTE_Gs 415
 .define NOTE_A 440
 .define NOTE_As 466
 .define NOTE_B 494
 
 .def LEFT_BUF = r2
 .def RIGHT_BUF = r3
 
 .def CHAN1_OSCL = r4
 .def CHAN1_OSCH = r5
 .def CHAN2_OSCL = r6
 .def CHAN2_OSCH = r7
 .def CHAN3_OSCL = r8
 .def CHAN3_OSCH = r9
 .def CHAN4_OSCL = r10
 .def CHAN4_OSCH = r11
 
 .def CHAN1_FRQL = r12
 .def CHAN1_FRQH = r13
 .def CHAN2_FRQL = r14
 .def CHAN2_FRQH = r15
 .def CHAN3_FRQL = r24
 .def CHAN3_FRQH = r25
 .def CHAN4_FRQL = r26
 .def CHAN4_FRQH = r27
 
 .def NOISEL = r0
 .def NOISEH = r1
 
 .NOLIST
 .include "m48def.inc"
 .LIST
 
 .cseg
 .org 0x00
 	rjmp start
 
 .org 0x09
 	rjmp timer
 
 start:
 	ldi r16, LOW(RAMEND)
 	out spl, r16
 	ldi r16, HIGH(RAMEND)
 	out sph, r16
 
 	ldi r16, 1
 	sts TIMSK2, r16
 	ldi r16, 0b001
 	sts TCCR2B, r16
 
 	ldi r16, 0xFF
 	out ddrd, r16
 	out ddrc, r16
 
 	ldi r16, 0xFF
 	mov LEFT_BUF, r16
 	mov RIGHT_BUF, r16
 
 	ldi r16, 0b0011
 	sts enable, r16
 
 	ldi r16, 0b00000000
 	sts waveform, r16
 
 	ldi r16, 0x80
 	sts chan1_tdut, r16
 	sts chan2_tdut, r16
 	sts chan3_tdut, r16
 	sts chan4_tdut, r16
 
 	ldi r16, 0xFF
 	sts chan1_tvol, r16
 	sts chan2_tvol, r16
 	sts chan3_tvol, r16
 	sts chan4_tvol, r16
 
 	ldi r16, 0x01
 	ldi r17, 0x00
 	mov NOISEL, r16
 	mov NOISEH, r17
 
 	ldi r16, 0x00
 	sts tick_timer, r16
 	sts tick_timer + 1, r16
 
 	ldi r16, 0xF0
 	sts chan1_env + 1, r16
 	sts chan2_env + 1, r16
 	sts chan3_env + 1, r16
 	sts chan4_env + 1, r16
 
 	ldi r16, 0x44
 	sts chan1_notes, r16
 	ldi r16, 0x00
 	sts chan2_notes, r16
 	ldi r16, 0x00
 	sts chan3_notes, r16
 	ldi r16, 0x00
 	sts chan4_notes, r16
 
 	ldi r16, 0x00
 	sts chan1_notes + 1, r16
 	ldi r16, 0x00
 	sts chan2_notes + 1, r16
 	ldi r16, 0x00
 	sts chan3_notes + 1, r16
 	ldi r16, 0x00
 	sts chan4_notes + 1, r16
 
 	ldi r16, 0b0000
 	sts note_on, r16
 
 	ldi r16, 0b00100000
 	ldi r17, 0b10000010
 	rcall command
 	ldi r16, 0b00100010
 	ldi r17, 0b11111110
 	rcall command
 	ldi r16, 0b01011100
 	ldi r17, 0b11111110
 	;rcall command
 	ldi r16, 0b01110110
 	ldi r17, 0b11111110
 	;rcall command
 	ldi r16, 0b01111001
 	ldi r17, 0b10000001
 	rcall command
 
 	sei
 
 loop:
 	rjmp loop
 
 command:
 	sbrs r17, 7
 	ret
 	mov r18, r16
 	lsr r18
 	andi r18, 0b00000011 ;channel
 	sbrs r16, 0
 	rjmp note_command
 effect_command:
 	mov r19, r16
 	lsl r19
 	andi r19, 0xF0 ;effect
 	mov r20, r17
 	lsl r20
 	sbrc r16, 7
 	ori r20, 0b00000001 ;argument
 
 	cpi r19, 0x00
 	breq apply_arp
 	cpi r19, 0x10
 	breq apply_pitch_slide_up
 	cpi r19, 0x20
 	breq apply_pitch_slide_down_a
 	cpi r19, 0x30
 	breq apply_portamento_a
 	cpi r19, 0x40
 	breq apply_vibrato_a
 	cpi r19, 0x50
 	breq apply_waveform_a
 	cpi r19, 0x60
 	breq apply_duty_cycle_a
 	cpi r19, 0x70
 	breq apply_tremolo_a
 	cpi r19, 0x80
 	breq apply_pwm_a
 	cpi r19, 0xA0
 	breq apply_volume_slide_up_a
 	cpi r19, 0xB0
 	breq apply_volume_slide_down_a
 	cpi r19, 0xC0
 	breq apply_volume_a
 	cpi r19, 0xF0
 	breq apply_fine_a
 	rjmp done
 
 apply_arp:
 	cpi r18, 0b00
 	breq apply_arp1
 	cpi r18, 0b01
 	breq apply_arp2
 	cpi r18, 0b10
 	breq apply_arp3
 	cpi r18, 0b11
 	breq apply_arp4
 	rjmp done
 apply_arp1:
 	sts chan1_notes + 1, r20
 	rjmp done
 apply_arp2:
 	sts chan2_notes + 1, r20
 	rjmp done
 apply_arp3:
 	sts chan3_notes + 1, r20
 	rjmp done
 apply_arp4:
 	sts chan4_notes + 1, r20
 	rjmp done
 
 apply_pitch_slide_down_a:
 	rjmp apply_pitch_slide_down
 
 apply_portamento_a:
 	rjmp apply_portamento
 
 apply_vibrato_a:
 	rjmp apply_vibrato
 
 apply_waveform_a:
 	rjmp apply_waveform
 
 apply_duty_cycle_a:
 	rjmp apply_duty_cycle
 
 apply_tremolo_a:
 	rjmp apply_tremolo
 
 apply_pwm_a:
 	rjmp apply_pwm
 
 apply_volume_slide_up_a:
 	rjmp apply_volume_slide_up
 
 apply_volume_slide_down_a:
 	rjmp apply_volume_slide_down
 
 apply_volume_a:
 	rjmp apply_volume_eff
 
 apply_fine_a:
 	rjmp apply_fine
 
 apply_pitch_slide_up:
 	cpi r18, 0b00
 	breq apply_pitch_slide_up1
 	cpi r18, 0b01
 	breq apply_pitch_slide_up2
 	cpi r18, 0b10
 	breq apply_pitch_slide_up3
 	cpi r18, 0b11
 	breq apply_pitch_slide_up4
 	rjmp done
 apply_pitch_slide_up1:
 	sts chan1_pit_slide, r20
 	lds r16, pit_slide_dir
 	ori r16, 0b0001
 	sts pit_slide_dir, r16
 	rjmp done
 apply_pitch_slide_up2:
 	sts chan2_pit_slide, r20
 	lds r16, pit_slide_dir
 	ori r16, 0b0010
 	sts pit_slide_dir, r16
 	rjmp done
 apply_pitch_slide_up3:
 	sts chan3_pit_slide, r20
 	lds r16, pit_slide_dir
 	ori r16, 0b0100
 	sts pit_slide_dir, r16
 	rjmp done
 apply_pitch_slide_up4:
 	sts chan4_pit_slide, r20
 	lds r16, pit_slide_dir
 	ori r16, 0b1000
 	sts pit_slide_dir, r16
 	rjmp done
 
 apply_pitch_slide_down:
 	cpi r18, 0b00
 	breq apply_pitch_slide_down1
 	cpi r18, 0b01
 	breq apply_pitch_slide_down2
 	cpi r18, 0b10
 	breq apply_pitch_slide_down3
 	cpi r18, 0b11
 	breq apply_pitch_slide_down4
 	rjmp done
 apply_pitch_slide_down1:
 	sts chan1_pit_slide, r20
 	lds r16, pit_slide_dir
 	andi r16, 0b1110
 	sts pit_slide_dir, r16
 	rjmp done
 apply_pitch_slide_down2:
 	sts chan2_pit_slide, r20
 	lds r16, pit_slide_dir
 	andi r16, 0b1101
 	sts pit_slide_dir, r16
 	rjmp done
 apply_pitch_slide_down3:
 	sts chan3_pit_slide, r20
 	lds r16, pit_slide_dir
 	andi r16, 0b1011
 	sts pit_slide_dir, r16
 	rjmp done
 apply_pitch_slide_down4:
 	sts chan4_pit_slide, r20
 	lds r16, pit_slide_dir
 	andi r16, 0b0111
 	sts pit_slide_dir, r16
 	rjmp done
 
 apply_portamento:
 	cpi r18, 0b00
 	breq apply_portamento1
 	cpi r18, 0b01
 	breq apply_portamento2
 	cpi r18, 0b10
 	breq apply_portamento3
 	cpi r18, 0b11
 	breq apply_portamento4
 	rjmp done
 apply_portamento1:
 	sts chan1_port, r20
 	rjmp done
 apply_portamento2:
 	sts chan2_port, r20
 	rjmp done
 apply_portamento3:
 	sts chan3_port, r20
 	rjmp done
 apply_portamento4:
 	sts chan4_port, r20
 	rjmp done
 
 apply_vibrato:
 	cpi r18, 0b00
 	breq apply_vibrato1
 	cpi r18, 0b01
 	breq apply_vibrato2
 	cpi r18, 0b10
 	breq apply_vibrato3
 	cpi r18, 0b11
 	breq apply_vibrato4
 	rjmp done
 apply_vibrato1:
 	sts chan1_vib, r20
 	rjmp done
 apply_vibrato2:
 	sts chan2_vib, r20
 	rjmp done
 apply_vibrato3:
 	sts chan3_vib, r20
 	rjmp done
 apply_vibrato4:
 	sts chan4_vib, r20
 	rjmp done
 
 apply_waveform:
 	lds r16, waveform
 	cpi r18, 0b00
 	breq apply_waveform1
 	cpi r18, 0b01
 	breq apply_waveform2
 	cpi r18, 0b10
 	breq apply_waveform3
 	cpi r18, 0b11
 	breq apply_waveform4
 	rjmp done_waveform
 apply_waveform1:
 	andi r16, 0b11111100
 	or r16, r20
 	rjmp done_waveform
 apply_waveform2:
 	andi r16, 0b11110011
 	lsl r20
 	lsl r20
 	or r16, r20
 	rjmp done_waveform
 apply_waveform3:
 	andi r16, 0b11001111
 	lsl r20
 	lsl r20
 	lsl r20
 	lsl r20
 	or r16, r20
 	rjmp done_waveform
 apply_waveform4:
 	andi r16, 0b00111111
 	lsl r20
 	lsl r20
 	lsl r20
 	lsl r20
 	lsl r20
 	lsl r20
 	or r16, r20
 done_waveform:
 	sts waveform, r16
 	rjmp done
 
 apply_duty_cycle:
 	cpi r18, 0b00
 	breq apply_duty_cycle1
 	cpi r18, 0b01
 	breq apply_duty_cycle2
 	cpi r18, 0b10
 	breq apply_duty_cycle3
 	cpi r18, 0b11
 	breq apply_duty_cycle4
 	rjmp done
 apply_duty_cycle1:
 	sts chan1_tdut, r20
 	rjmp done
 apply_duty_cycle2:
 	sts chan2_tdut, r20
 	rjmp done
 apply_duty_cycle3:
 	sts chan3_tdut, r20
 	rjmp done
 apply_duty_cycle4:
 	sts chan4_tdut, r20
 	rjmp done
 
 apply_tremolo:
 	cpi r18, 0b00
 	breq apply_tremolo1
 	cpi r18, 0b01
 	breq apply_tremolo2
 	cpi r18, 0b10
 	breq apply_tremolo3
 	cpi r18, 0b11
 	breq apply_tremolo4
 	rjmp done
 apply_tremolo1:
 	sts chan1_trm, r20
 	rjmp done
 apply_tremolo2:
 	sts chan2_trm, r20
 	rjmp done
 apply_tremolo3:
 	sts chan3_trm, r20
 	rjmp done
 apply_tremolo4:
 	sts chan4_trm, r20
 	rjmp done
 
 apply_pwm:
 	cpi r18, 0b00
 	breq apply_pwm1
 	cpi r18, 0b01
 	breq apply_pwm2
 	cpi r18, 0b10
 	breq apply_pwm3
 	cpi r18, 0b11
 	breq apply_pwm4
 	rjmp done
 apply_pwm1:
 	sts chan1_pwm, r20
 	rjmp done
 apply_pwm2:
 	sts chan2_pwm, r20
 	rjmp done
 apply_pwm3:
 	sts chan3_pwm, r20
 	rjmp done
 apply_pwm4:
 	sts chan4_pwm, r20
 	rjmp done
 
 apply_volume_slide_up:
 	cpi r18, 0b00
 	breq apply_volume_slide_up1
 	cpi r18, 0b01
 	breq apply_volume_slide_up2
 	cpi r18, 0b10
 	breq apply_volume_slide_up3
 	cpi r18, 0b11
 	breq apply_volume_slide_up4
 	rjmp done
 apply_volume_slide_up1:
 	sts chan1_vol_slide, r20
 	lds r16, vol_slide_dir
 	ori r16, 0b0001
 	sts vol_slide_dir, r16
 	rjmp done
 apply_volume_slide_up2:
 	sts chan2_vol_slide, r20
 	lds r16, vol_slide_dir
 	ori r16, 0b0010
 	sts vol_slide_dir, r16
 	rjmp done
 apply_volume_slide_up3:
 	sts chan3_vol_slide, r20
 	lds r16, vol_slide_dir
 	ori r16, 0b0100
 	sts vol_slide_dir, r16
 	rjmp done
 apply_volume_slide_up4:
 	sts chan4_vol_slide, r20
 	lds r16, vol_slide_dir
 	ori r16, 0b1000
 	sts vol_slide_dir, r16
 	rjmp done
 
 apply_volume_slide_down:
 	cpi r18, 0b00
 	breq apply_volume_slide_down1
 	cpi r18, 0b01
 	breq apply_volume_slide_down2
 	cpi r18, 0b10
 	breq apply_volume_slide_down3
 	cpi r18, 0b11
 	breq apply_volume_slide_down4
 	rjmp done
 apply_volume_slide_down1:
 	sts chan1_vol_slide, r20
 	lds r16, vol_slide_dir
 	andi r16, 0b1110
 	sts vol_slide_dir, r16
 	rjmp done
 apply_volume_slide_down2:
 	sts chan2_vol_slide, r20
 	lds r16, vol_slide_dir
 	andi r16, 0b1101
 	sts vol_slide_dir, r16
 	rjmp done
 apply_volume_slide_down3:
 	sts chan3_vol_slide, r20
 	lds r16, vol_slide_dir
 	andi r16, 0b1011
 	sts vol_slide_dir, r16
 	rjmp done
 apply_volume_slide_down4:
 	sts chan4_vol_slide, r20
 	lds r16, vol_slide_dir
 	andi r16, 0b0111
 	sts vol_slide_dir, r16
 	rjmp done
 
 apply_volume_eff:
 	cpi r18, 0b00
 	breq apply_volume1_eff
 	cpi r18, 0b01
 	breq apply_volume2_eff
 	cpi r18, 0b10
 	breq apply_volume3_eff
 	cpi r18, 0b11
 	breq apply_volume4_eff
 	rjmp done
 apply_volume1_eff:
 	sts chan1_tvol, r20
 	rjmp done
 apply_volume2_eff:
 	sts chan1_tvol, r20
 	rjmp done
 apply_volume3_eff:
 	sts chan1_tvol, r20
 	rjmp done
 apply_volume4_eff:
 	sts chan1_tvol, r20
 	rjmp done
 
 apply_fine:
 	cpi r18, 0b00
 	breq apply_fine1
 	cpi r18, 0b01
 	breq apply_fine2
 	cpi r18, 0b10
 	breq apply_fine3
 	cpi r18, 0b11
 	breq apply_fine4
 	rjmp done
 apply_fine1:
 	sts chan1_fine, r20
 	rjmp done
 apply_fine2:
 	sts chan2_fine, r20
 	rjmp done
 apply_fine3:
 	sts chan3_fine, r20
 	rjmp done
 apply_fine4:
 	sts chan4_fine, r20
 	rjmp done
 
 note_command:
 	mov r19, r16
 	lsl r19
 	andi r19, 0xF0 ;note
 	mov r20, r17
 	lsl r20
 	sbrc r16, 7
 	ori r20, 0b00000001
 	lsl r17
 	andi r17, 0b11111000 ;volume
 	andi r20, 0x0F
 	or r20, r19 ;note/octave
 
 	cpi r18, 0b00
 	breq set_chan1
 	cpi r18, 0b01
 	breq set_chan2
 	cpi r18, 0b10
 	breq set_chan3a
 	cpi r18, 0b11
 	breq set_chan4a
 	rjmp done
 
 set_chan1:
 	cpi r19, 0x00
 	breq skip_note1
 	cpi r19, 0x10
 	breq reset_note1
 	cpi r19, 0x20
 	breq enable_note1
 	cpi r19, 0x30
 	breq disable_note1
 	lds r16, enable
 	ori r16, 0b0001
 	sts enable, r16
 	lds r16, note_on
 	ori r16, 0b0001
 	sts note_on, r16
 	sts chan1_notes, r20
 	rjmp skip_note1
 reset_note1:
 	clr CHAN1_OSCL
 	clr CHAN1_OSCH
 	rjmp skip_note1
 enable_note1:
 	lds r16, enable
 	ori r16, 0b0001
 	sts enable, r16
 	rjmp skip_note1
 disable_note1:
 	lds r16, enable
 	andi r16, 0b1110
 	sts enable, r16
 	rjmp skip_note1
 skip_note1:
 	cpi r17, 0x00
 	breq done_a
 	sts chan1_tvol, r17
 	rjmp done
 
 set_chan3a:
 	rjmp set_chan3
 
 set_chan4a:
 	rjmp set_chan4b
 
 set_chan2:
 	cpi r19, 0x00
 	breq skip_note2
 	cpi r19, 0x10
 	breq reset_note2
 	cpi r19, 0x20
 	breq enable_note2
 	cpi r19, 0x30
 	breq disable_note2
 	lds r16, enable
 	ori r16, 0b0010
 	sts enable, r16
 	lds r16, note_on
 	ori r16, 0b0010
 	sts note_on, r16
 	sts chan2_notes, r20
 	rjmp skip_note2
 reset_note2:
 	clr CHAN2_OSCL
 	clr CHAN2_OSCH
 	rjmp skip_note2
 enable_note2:
 	lds r16, enable
 	ori r16, 0b0010
 	sts enable, r16
 	rjmp skip_note2
 disable_note2:
 	lds r16, enable
 	andi r16, 0b1101
 	sts enable, r16
 	rjmp skip_note2
 skip_note2:
 	cpi r17, 0x00
 	breq done_a
 	sts chan2_tvol, r17
 	rjmp done
 
 set_chan4b:
 	rjmp set_chan4
 
 done_a:
 	rjmp done
 
 set_chan3:
 	cpi r19, 0x00
 	breq skip_note3
 	cpi r19, 0x10
 	breq reset_note3
 	cpi r19, 0x20
 	breq enable_note3
 	cpi r19, 0x30
 	breq disable_note3
 	lds r16, enable
 	ori r16, 0b0100
 	sts enable, r16
 	lds r16, note_on
 	ori r16, 0b0100
 	sts note_on, r16
 	sts chan3_notes, r20
 	rjmp skip_note3
 reset_note3:
 	clr CHAN3_OSCL
 	clr CHAN3_OSCH
 	rjmp skip_note3
 enable_note3:
 	lds r16, enable
 	ori r16, 0b0100
 	sts enable, r16
 	rjmp skip_note3
 disable_note3:
 	lds r16, enable
 	andi r16, 0b1011
 	sts enable, r16
 	rjmp skip_note3
 skip_note3:
 	cpi r17, 0x00
 	breq done
 	sts chan3_tvol, r17
 	rjmp done
 
 set_chan4:
 	cpi r19, 0x00
 	breq skip_note4
 	cpi r19, 0x10
 	breq reset_note4
 	cpi r19, 0x20
 	breq enable_note4
 	cpi r19, 0x30
 	breq disable_note4
 	lds r16, enable
 	ori r16, 0b1000
 	sts enable, r16
 	lds r16, note_on
 	ori r16, 0b1000
 	sts note_on, r16
 	sts chan4_notes, r20
 	rjmp skip_note4
 reset_note4:
 	clr CHAN3_OSCL
 	clr CHAN3_OSCH
 	rjmp skip_note4
 enable_note4:
 	lds r16, enable
 	ori r16, 0b1000
 	sts enable, r16
 	rjmp skip_note4
 disable_note4:
 	lds r16, enable
 	andi r16, 0b0111
 	sts enable, r16
 	rjmp skip_note4
 skip_note4:
 	cpi r17, 0x00
 	breq done
 	sts chan4_tvol, r17
 	rjmp done
 
 done:
 	ret
 
 timer:
 	mov r16, LEFT_BUF
 	lsr r16
 	lsr r16
 
 	mov r17, RIGHT_BUF
 	lsr r17
 	lsr r17
 
 	out portd, r16
 	out portc, r17
 
 	clr LEFT_BUF
 	clr RIGHT_BUF
 
 	add CHAN1_OSCL, CHAN1_FRQL
 	adc CHAN1_OSCH, CHAN1_FRQH
 	add CHAN2_OSCL, CHAN2_FRQL
 	adc CHAN2_OSCH, CHAN2_FRQH
 	add CHAN3_OSCL, CHAN3_FRQL
 	adc CHAN3_OSCH, CHAN3_FRQH
 	add CHAN4_OSCL, CHAN4_FRQL
 	adc CHAN4_OSCH, CHAN4_FRQH
 
 	lds r16, waveform
 	lds r22, enable
 
 	mov r18, r16
 	andi r18, 0b00000011
 	mov r19, CHAN1_OSCH
 	lds r20, chan1_vol
 	lds r21, chan1_dut
 	rcall generate
 	sbrc r22, 0
 	add LEFT_BUF, r17
 
 	lsr r16
 	lsr r16
 	mov r18, r16
 	andi r18, 0b00000011
 	mov r19, CHAN2_OSCH
 	lds r20, chan2_vol
 	lds r21, chan2_dut
 	rcall generate
 	sbrc r22, 1
 	add LEFT_BUF, r17
 
 	lsr r16
 	lsr r16
 	mov r18, r16
 	andi r18, 0b00000011
 	mov r19, CHAN3_OSCH
 	lds r20, chan3_vol
 	lds r21, chan3_dut
 	rcall generate
 	sbrc r22, 2
 	add RIGHT_BUF, r17
 
 	lsr r16
 	lsr r16
 	mov r18, r16
 	andi r18, 0b00000011
 	mov r19, CHAN4_OSCH
 	lds r20, chan4_vol
 	lds r21, chan4_dut
 	rcall generate
 	sbrc r22, 3
 	add RIGHT_BUF, r17
 
 	lds r16, tick_timer
 	cpi r16, 0x00
 	brne skip22
 
 	lds r20, vol_slide_dir
 
 	lds r16, chan1_tvol
 	lds r17, chan1_vol_slide
 	sbrc r20, 0
 	rjmp up1b
 	sbc r16, r17
 	brcc down1b
 	clr r16
 up1b:
 	add r16, r17
 	brcc down1b
 	ser r16
 down1b:
 	sts chan1_tvol, r16
 	sts chan1_ptrm, r16
 
 	lds r16, chan2_tvol
 	lds r17, chan2_vol_slide
 	sbrc r20, 1
 	rjmp up2b
 	sbc r16, r17
 	brcc down2b
 	clr r16
 up2b:
 	add r16, r17
 	brcc down2b
 	ser r16
 down2b:
 	sts chan2_tvol, r16
 	sts chan2_ptrm, r16
 
 	rjmp skip23
 skip22:
 	rjmp skip2
 skip23:
 
 	lds r16, chan3_tvol
 	lds r17, chan3_vol_slide
 	sbrc r20, 2
 	rjmp up3b
 	sbc r16, r17
 	brcc down3b
 	clr r16
 up3b:
 	add r16, r17
 	brcc down3b
 	ser r16
 down3b:
 	sts chan3_tvol, r16
 	sts chan3_ptrm, r16
 
 	lds r16, chan4_tvol
 	lds r17, chan4_vol_slide
 	sbrc r20, 3
 	rjmp up4b
 	sbc r16, r17
 	brcc down4b
 	clr r16
 up4b:
 	add r16, r17
 	brcc down4b
 	ser r16
 down4b:
 	sts chan4_tvol, r16
 	sts chan4_ptrm, r16
 
 	rjmp skip3
 
 skip2:
 	rjmp skip
 
 skip3:
 	lds r16, note_on
 	lds r17, chan1_notes + 1
 	cpi r17, 0x00
 	breq skip11
 	ori r16, 0b0001
 
 skip11:
 	sbrs r16, 0
 	rjmp skip7
 	andi r16, 0b1110
 	sts note_on, r16
 
 	lds r16, chan1_notes
 	lds r17, chan1_notes + 1
 	rcall handle_note
 	sts chan1_tpit, r16
 	sts chan1_tpit + 1, r17
 
 skip7:
 	lds r16, note_on
 	lds r17, chan2_notes + 1
 	cpi r17, 0x00
 	breq skip12
 	ori r16, 0b0010
 
 skip12:
 	sbrs r16, 1
 	rjmp skip8
 	andi r16, 0b1101
 	sts note_on, r16
 
 	lds r16, chan2_notes
 	lds r17, chan2_notes + 1
 	rcall handle_note
 	sts chan2_tpit, r16
 	sts chan2_tpit + 1, r17
 
 skip8:
 	lds r16, note_on
 	lds r17, chan3_notes + 1
 	cpi r17, 0x00
 	breq skip13
 	ori r16, 0b0100
 
 skip13:
 	sbrs r16, 2
 	rjmp skip9
 	andi r16, 0b1011
 	sts note_on, r16
 
 	lds r16, chan3_notes
 	lds r17, chan3_notes + 1
 	rcall handle_note
 	sts chan3_tpit, r16
 	sts chan3_tpit + 1, r17
 
 skip9:
 	lds r16, note_on
 	lds r17, chan4_notes + 1
 	cpi r17, 0x00
 	breq skip14
 	ori r16, 0b1000
 
 skip14:
 	sbrs r16, 3
 	rjmp skip10
 	andi r16, 0b0111
 	sts note_on, r16
 
 	lds r16, chan4_notes
 	lds r17, chan4_notes + 1
 	rcall handle_note
 	sts chan4_tpit, r16
 	sts chan4_tpit + 1, r17
 
 skip10:
 	lds CHAN1_FRQL, chan1_pvib
 	lds CHAN1_FRQH, chan1_pvib + 1
 	lds CHAN2_FRQL, chan2_pvib
 	lds CHAN2_FRQH, chan2_pvib + 1
 	lds CHAN3_FRQL, chan3_pvib
 	lds CHAN3_FRQH, chan3_pvib + 1
 	lds CHAN4_FRQL, chan4_pvib
 	lds CHAN4_FRQH, chan4_pvib + 1
 
 	lds r21, slide_timer
 	inc r21
 	cpi r21, 0x4
 	brne skip15
 	clr r21
 skip15:
 	sts slide_timer, r21
 	cpi r21, 0x00
 	brne skip16
 	ser r21
 	rjmp skip17
 skip16:
 	clr r21
 skip17:
 	lds r20, pit_slide_dir
 
 	lds r16, chan1_tpit
 	lds r17, chan1_tpit + 1
 	sbrs r21, 0
 	rjmp skip18
 	lds r18, chan1_pit_slide
 	ldi r19, 0x00
 	sbrc r20, 0
 	rjmp up1
 	cpi r17, 0x00
 	brne down1a
 	cpi r16, 0x00
 	breq down1
 down1a:
 	sbc r16, r18
 	brcc down1
 	dec r17
 	rjmp down1
 up1:
 	add r16, r18
 	adc r17, r19
 down1:
 	sts chan1_tpit, r16
 	sts chan1_tpit + 1, r17
 skip18:
 	sbrs r21, 0
 	rjmp port1
 	lds r18, chan1_port
 	cpi r18, 0x00
 	breq skip_port1
 	mov r23, CHAN1_FRQL
 	cpi r23, 0x00
 	brne ne1
 	mov r23, CHAN1_FRQH
 	cpi r23, 0x00
 	breq skip_port1
 ne1:
 	cp CHAN1_FRQH, r17
 	brlo higher1
 	cp r17, CHAN1_FRQH
 	brlo lower1
 	cp CHAN1_FRQL, r16
 	brlo higher1
 	cp r16, CHAN1_FRQL
 	brlo lower1
 	rjmp skip_port1
 higher1:
 	ldi r19, 0x00
 	add CHAN1_FRQL, r18
 	adc CHAN1_FRQH, r19
 	cp r17, CHAN1_FRQH
 	brlo skip_port1
 	cp CHAN1_FRQH, r17
 	brlo port1
 	cp r16, CHAN1_FRQL
 	brlo skip_port1
 	rjmp port1
 lower1:
 	clc
 	sbc CHAN1_FRQL, r18
 	brcc lower1a
 	dec CHAN1_FRQH
 lower1a:
 	cp CHAN1_FRQH, r17
 	brlo skip_port1
 	cp r17, CHAN1_FRQH
 	brlo port1
 	cp CHAN1_FRQL, r16
 	brlo skip_port1
 	rjmp port1
 skip_port1:
 	mov CHAN1_FRQL, r16
 	mov CHAN1_FRQH, r17
 port1:
 
 	lds r16, chan2_tpit
 	lds r17, chan2_tpit + 1
 	sbrs r21, 0
 	rjmp skip19
 	lds r18, chan2_pit_slide
 	ldi r19, 0x00
 	sbrc r20, 1
 	rjmp up2
 	cpi r17, 0x00
 	brne down2a
 	cpi r16, 0x00
 	breq down2
 down2a:
 	sbc r16, r18
 	brcc down2
 	dec r17
 	rjmp down2
 up2:
 	add r16, r18
 	adc r17, r19
 down2:
 	sts chan2_tpit, r16
 	sts chan2_tpit + 1, r17
 skip19:
 	sbrs r21, 0
 	rjmp port2
 	lds r18, chan2_port
 	cpi r18, 0x00
 	breq skip_port2
 	mov r23, CHAN2_FRQL
 	cpi r23, 0x00
 	brne ne2
 	mov r23, CHAN2_FRQH
 	cpi r23, 0x00
 	breq skip_port2
 ne2:
 	cp CHAN2_FRQH, r17
 	brlo higher2
 	cp r17, CHAN2_FRQH
 	brlo lower2
 	cp CHAN2_FRQL, r16
 	brlo higher2
 	cp r16, CHAN2_FRQL
 	brlo lower2
 	rjmp skip_port2
 higher2:
 	ldi r19, 0x00
 	add CHAN2_FRQL, r18
 	adc CHAN2_FRQH, r19
 	cp r17, CHAN2_FRQH
 	brlo skip_port2
 	cp CHAN2_FRQH, r17
 	brlo port2
 	cp r16, CHAN2_FRQL
 	brlo skip_port2
 	rjmp port2
 lower2:
 	clc
 	sbc CHAN2_FRQL, r18
 	brcc lower2a
 	dec CHAN2_FRQH
 lower2a:
 	cp CHAN2_FRQH, r17
 	brlo skip_port2
 	cp r17, CHAN2_FRQH
 	brlo port2
 	cp CHAN2_FRQL, r16
 	brlo skip_port2
 	rjmp port2
 skip_port2:
 	mov CHAN2_FRQL, r16
 	mov CHAN2_FRQH, r17
 port2:
 
 	lds r16, chan3_tpit
 	lds r17, chan3_tpit + 1
 	sbrs r21, 0
 	rjmp skip20
 	lds r18, chan3_pit_slide
 	ldi r19, 0x00
 	sbrc r20, 2
 	rjmp up3
 	cpi r17, 0x00
 	brne down3a
 	cpi r16, 0x00
 	breq down3
 down3a:
 	sbc r16, r18
 	brcc down3
 	dec r17
 	rjmp down3
 up3:
 	add r16, r18
 	adc r17, r19
 down3:
 	sts chan3_tpit, r16
 	sts chan3_tpit + 1, r17
 skip20:
 	sbrs r21, 0
 	rjmp port3
 	lds r18, chan3_port
 	cpi r18, 0x00
 	breq skip_port3
 	mov r23, CHAN3_FRQL
 	cpi r23, 0x00
 	brne ne3
 	mov r23, CHAN3_FRQH
 	cpi r23, 0x00
 	breq skip_port3
 ne3:
 	cp CHAN3_FRQH, r17
 	brlo higher3
 	cp r17, CHAN3_FRQH
 	brlo lower3
 	cp CHAN3_FRQL, r16
 	brlo higher3
 	cp r16, CHAN3_FRQL
 	brlo lower3
 	rjmp skip_port3
 higher3:
 	ldi r19, 0x00
 	add CHAN3_FRQL, r18
 	adc CHAN3_FRQH, r19
 	cp r17, CHAN3_FRQH
 	brlo skip_port3
 	cp CHAN3_FRQH, r17
 	brlo port3
 	cp r16, CHAN3_FRQL
 	brlo skip_port3
 	rjmp port3
 lower3:
 	clc
 	sbc CHAN3_FRQL, r18
 	brcc lower3a
 	dec CHAN3_FRQH
 lower3a:
 	cp CHAN3_FRQH, r17
 	brlo skip_port3
 	cp r17, CHAN3_FRQH
 	brlo port3
 	cp CHAN3_FRQL, r16
 	brlo skip_port3
 	rjmp port3
 skip_port3:
 	mov CHAN3_FRQL, r16
 	mov CHAN3_FRQH, r17
 port3:
 
 	lds r16, chan4_tpit
 	lds r17, chan4_tpit + 1
 	sbrs r21, 0
 	rjmp skip21
 	lds r18, chan4_pit_slide
 	ldi r19, 0x00
 	sbrc r20, 3
 	rjmp up4
 	cpi r17, 0x00
 	brne down4a
 	cpi r16, 0x00
 	breq down4
 down4a:
 	sbc r16, r18
 	brcc down4
 	dec r17
 	rjmp down4
 up4:
 	add r16, r18
 	adc r17, r19
 down4:
 	sts chan4_tpit, r16
 	sts chan4_tpit + 1, r17
 skip21:
 	sbrs r21, 0
 	rjmp port4
 	lds r18, chan4_port
 	cpi r18, 0x00
 	breq skip_port4
 	mov r23, CHAN4_FRQL
 	cpi r23, 0x00
 	brne ne4
 	mov r23, CHAN4_FRQH
 	cpi r23, 0x00
 	breq skip_port4
 ne4:
 	cp CHAN4_FRQH, r17
 	brlo higher4
 	cp r17, CHAN4_FRQH
 	brlo lower4
 	cp CHAN4_FRQL, r16
 	brlo higher4
 	cp r16, CHAN4_FRQL
 	brlo lower4
 	rjmp skip_port4
 higher4:
 	ldi r19, 0x00
 	add CHAN4_FRQL, r18
 	adc CHAN4_FRQH, r19
 	cp r17, CHAN4_FRQH
 	brlo skip_port4
 	cp CHAN4_FRQH, r17
 	brlo port4
 	cp r16, CHAN4_FRQL
 	brlo skip_port4
 	rjmp port4
 lower4:
 	clc
 	sbc CHAN4_FRQL, r18
 	brcc lower4a
 	dec CHAN4_FRQH
 lower4a:
 	cp CHAN4_FRQH, r17
 	brlo skip_port4
 	cp r17, CHAN4_FRQH
 	brlo port4
 	cp CHAN4_FRQL, r16
 	brlo skip_port4
 	rjmp port4
 skip_port4:
 	mov CHAN4_FRQL, r16
 	mov CHAN4_FRQH, r17
 port4:
 	sts chan1_pvib, CHAN1_FRQL
 	sts chan1_pvib + 1, CHAN1_FRQH
 	sts chan2_pvib, CHAN2_FRQL
 	sts chan2_pvib + 1, CHAN2_FRQH
 	sts chan3_pvib, CHAN3_FRQL
 	sts chan3_pvib + 1, CHAN3_FRQH
 	sts chan4_pvib, CHAN4_FRQL
 	sts chan4_pvib + 1, CHAN4_FRQH
 
 	lds r21, vibrato_timer
 	inc r21
 	cpi r21, 0x8
 	brne skip27
 	clr r21
 skip27:
 	sts vibrato_timer, r21
 
 	push r0
 	push r1
 
 	lds r16, chan1_tvib
 	lds r17, chan1_vib
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	andi r19, 0x0F
 
 	cpi r21, 0x00
 	brne skip26
 
 	add r16, r17
 	sts chan1_tvib, r16
 skip26:
 	sbrc r16, 7
 	com r16
 	lsr r16
 	lsr r16
 	lsr r16
 	mul r16, r19
 	mov r16, r0
 	lsr r16
 	lsr r16
 	lsr r16
 	ldi r19, 0x00
 	lds r18, chan1_fine
 	add r16, r18
 	add CHAN1_FRQL, r16
 	adc CHAN1_FRQH, r19
 
 	lds r16, chan2_tvib
 	lds r17, chan2_vib
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	andi r19, 0x0F
 
 	cpi r21, 0x00
 	brne skip30
 
 	add r16, r17
 	sts chan2_tvib, r16
 skip30:
 	sbrc r16, 7
 	com r16
 	lsr r16
 	lsr r16
 	lsr r16
 	mul r16, r19
 	mov r16, r0
 	lsr r16
 	lsr r16
 	lsr r16
 	ldi r19, 0x00
 	lds r18, chan2_fine
 	add r16, r18
 	add CHAN2_FRQL, r16
 	adc CHAN2_FRQH, r19
 
 	lds r16, chan3_tvib
 	lds r17, chan3_vib
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	andi r19, 0x0F
 
 	cpi r21, 0x00
 	brne skip28
 
 	add r16, r17
 	sts chan3_tvib, r16
 skip28:
 	sbrc r16, 7
 	com r16
 	lsr r16
 	lsr r16
 	lsr r16
 	mul r16, r19
 	mov r16, r0
 	lsr r16
 	lsr r16
 	lsr r16
 	ldi r19, 0x00
 	lds r18, chan3_fine
 	add r16, r18
 	add CHAN3_FRQL, r16
 	adc CHAN3_FRQH, r19
 
 	lds r16, chan4_tvib
 	lds r17, chan4_vib
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	andi r19, 0x0F
 
 	cpi r21, 0x00
 	brne skip29
 
 	add r16, r17
 	sts chan4_tvib, r16
 skip29:
 	sbrc r16, 7
 	com r16
 	lsr r16
 	lsr r16
 	lsr r16
 	mul r16, r19
 	mov r16, r0
 	lsr r16
 	lsr r16
 	lsr r16
 	ldi r19, 0x00
 	lds r18, chan4_fine
 	add r16, r18
 	add CHAN4_FRQL, r16
 	adc CHAN4_FRQH, r19
 
 	lds r16, chan1_ttrm
 	lds r17, chan1_trm
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	andi r19, 0x0F
 	lsl r19
 	lsl r19
 	lsl r19
 	lsl r19
 	cpi r21, 0x00
 	brne skip31
 	add r16, r17
 	sts chan1_ttrm, r16
 skip31:
 	sbrc r16, 7
 	com r16
 	lsl r16
 	mul r16, r19
 	mov r16, r1
 	lds r18, chan1_ptrm
 	clc
 	sbc r18, r16
 	brcc skip32
 	clr r18
 skip32:
 	sts chan1_vol, r18
 
 	lds r16, chan2_ttrm
 	lds r17, chan2_trm
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	andi r19, 0x0F
 	lsl r19
 	lsl r19
 	lsl r19
 	lsl r19
 	cpi r21, 0x00
 	brne skip33
 	add r16, r17
 	sts chan2_ttrm, r16
 skip33:
 	sbrc r16, 7
 	com r16
 	lsl r16
 	mul r16, r19
 	mov r16, r1
 	lds r18, chan2_ptrm
 	clc
 	sbc r18, r16
 	brcc skip34
 	clr r18
 skip34:
 	sts chan2_vol, r18
 
 	lds r16, chan3_ttrm
 	lds r17, chan3_trm
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	andi r19, 0x0F
 	lsl r19
 	lsl r19
 	lsl r19
 	lsl r19
 	cpi r21, 0x00
 	brne skip38
 	add r16, r17
 	sts chan3_ttrm, r16
 skip38:
 	sbrc r16, 7
 	com r16
 	lsl r16
 	mul r16, r19
 	mov r16, r1
 	lds r18, chan3_ptrm
 	clc
 	sbc r18, r16
 	brcc skip35
 	clr r18
 skip35:
 	sts chan3_vol, r18
 
 	lds r16, chan4_ttrm
 	lds r17, chan4_trm
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	andi r19, 0x0F
 	lsl r19
 	lsl r19
 	lsl r19
 	lsl r19
 	cpi r21, 0x00
 	brne skip36
 	add r16, r17
 	sts chan4_ttrm, r16
 skip36:
 	sbrc r16, 7
 	com r16
 	lsl r16
 	mul r16, r19
 	mov r16, r1
 	lds r18, chan4_ptrm
 	clc
 	sbc r18, r16
 	brcc skip37
 	clr r18
 skip37:
 	sts chan4_vol, r18
 
 	lds r16, chan1_tpwm
 	lds r17, chan1_pwm
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	lsr r17
 	lsr r17
 	lsr r17
 	andi r19, 0x0F
 	lsl r19
 	lsl r19
 	lsl r19
 	lsl r19
 	cpi r21, 0x00
 	brne skip39
 	add r16, r17
 	sts chan1_tpwm, r16
 skip39:
 	sbrc r16, 7
 	com r16
 	mul r16, r19
 	mov r16, r1
 	lds r18, chan1_tdut
 	add r18, r16
 	sts chan1_dut, r18
 
 	lds r16, chan2_tpwm
 	lds r17, chan2_pwm
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	lsr r17
 	lsr r17
 	lsr r17
 	andi r19, 0x0F
 	lsl r19
 	lsl r19
 	lsl r19
 	lsl r19
 	cpi r21, 0x00
 	brne skip40
 	add r16, r17
 	sts chan2_tpwm, r16
 skip40:
 	sbrc r16, 7
 	com r16
 	mul r16, r19
 	mov r16, r1
 	lds r18, chan2_tdut
 	add r18, r16
 	sts chan2_dut, r18
 
 	lds r16, chan3_tpwm
 	lds r17, chan3_pwm
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	lsr r17
 	lsr r17
 	lsr r17
 	andi r19, 0x0F
 	lsl r19
 	lsl r19
 	lsl r19
 	lsl r19
 	cpi r21, 0x00
 	brne skip41
 	add r16, r17
 	sts chan3_tpwm, r16
 skip41:
 	sbrc r16, 7
 	com r16
 	mul r16, r19
 	mov r16, r1
 	lds r18, chan3_tdut
 	add r18, r16
 	sts chan3_dut, r18
 
 	lds r16, chan4_tpwm
 	lds r17, chan4_pwm
 	mov r19, r17
 	andi r17, 0xF0
 	lsr r17
 	lsr r17
 	lsr r17
 	lsr r17
 	andi r19, 0x0F
 	lsl r19
 	lsl r19
 	lsl r19
 	lsl r19
 	cpi r21, 0x00
 	brne skip42
 	add r16, r17
 	sts chan4_tpwm, r16
 skip42:
 	sbrc r16, 7
 	com r16
 	mul r16, r19
 	mov r16, r1
 	lds r18, chan4_tdut
 	add r18, r16
 	sts chan4_dut, r18
 
 	pop r1
 	pop r0
 
 skip:
 	lds r16, tick_timer
 	inc r16
 	sts tick_timer, r16
 
 	reti
 
 handle_note:
 	lds r18, arp_timer
 	inc r18
 	mov r19, r18
 	lsr r19
 	lsr r19
 	lsr r19
 	lsr r19
 	lsr r19
 	andi r19, 0b11
 	cpi r19, 0b11
 	brne skip5
 	ldi r18, 0x0
 
 skip5:
 	sts arp_timer, r18
 
 	sbrc r19, 0
 	rjmp arp1
 	sbrc r19, 1
 	rjmp arp2
 	rjmp skip6
 
 arp1:
 	andi r17, 0xF0
 	add r16, r17
 	brcc skip6
 	ldi r18, 0x41
 	add r16, r18
 
 arp2:
 	lsl r17
 	lsl r17
 	lsl r17
 	lsl r17
 	add r16, r17
 	brcc skip6
 	ldi r18, 0x41
 	add r16, r18
 
 skip6:
 	rjmp note_freq
 
 note_freq:
 	mov r19, r16
 	lsr r16
 	lsr r16
 	lsr r16
 	lsr r16
 	cpi r16, 0x04
 	breq setc
 	cpi r16, 0x05
 	breq setcs
 	cpi r16, 0x06
 	breq setd
 	cpi r16, 0x07
 	breq setds
 	cpi r16, 0x08
 	breq sete
 	cpi r16, 0x09
 	breq setf
 	cpi r16, 0x0A
 	breq setfs
 	cpi r16, 0x0B
 	breq setg
 	cpi r16, 0x0C
 	breq setgs
 	cpi r16, 0x0D
 	breq seta
 	cpi r16, 0x0E
 	breq setas
 	cpi r16, 0x0F
 	breq setb
 	ret
 setc:
 	ldi r16, LOW(NOTE_C)
 	ldi r17, HIGH(NOTE_C)
 	rjmp skip4
 setcs:
 	ldi r16, LOW(NOTE_Cs)
 	ldi r17, HIGH(NOTE_Cs)
 	rjmp skip4
 setd:
 	ldi r16, LOW(NOTE_D)
 	ldi r17, HIGH(NOTE_D)
 	rjmp skip4
 setds:
 	ldi r16, LOW(NOTE_Ds)
 	ldi r17, HIGH(NOTE_Ds)
 	rjmp skip4
 sete:
 	ldi r16, LOW(NOTE_E)
 	ldi r17, HIGH(NOTE_E)
 	rjmp skip4
 setf:
 	ldi r16, LOW(NOTE_F)
 	ldi r17, HIGH(NOTE_F)
 	rjmp skip4
 setfs:
 	ldi r16, LOW(NOTE_Fs)
 	ldi r17, HIGH(NOTE_Fs)
 	rjmp skip4
 setg:
 	ldi r16, LOW(NOTE_G)
 	ldi r17, HIGH(NOTE_G)
 	rjmp skip4
 setgs:
 	ldi r16, LOW(NOTE_Gs)
 	ldi r17, HIGH(NOTE_Gs)
 	rjmp skip4
 seta:
 	ldi r16, LOW(NOTE_A)
 	ldi r17, HIGH(NOTE_A)
 	rjmp skip4
 setas:
 	ldi r16, LOW(NOTE_As)
 	ldi r17, HIGH(NOTE_As)
 	rjmp skip4
 setb:
 	ldi r16, LOW(NOTE_B)
 	ldi r17, HIGH(NOTE_B)
 	rjmp skip4
 skip4:
 	andi r19, 0x0F
 	cpi r19, 0x01
 	breq seto1
 	cpi r19, 0x02
 	breq seto2
 	cpi r19, 0x03
 	breq seto3
 	cpi r19, 0x04
 	breq seto4
 	cpi r19, 0x05
 	breq seto5
 	cpi r19, 0x06
 	breq seto6
 	cpi r19, 0x07
 	breq seto7
 	cpi r19, 0x08
 	breq seto8
 	ret
 seto1:
 	lsr r17
 	ror r16
 	lsr r17
 	ror r16
 	lsr r17
 	ror r16
 	ret
 seto2:
 	lsr r17
 	ror r16
 	lsr r17
 	ror r16
 	ret
 seto3:
 	lsr r17
 	ror r16
 	ret
 seto4:
 	ret
 seto5:
 	lsl r16
 	rol r17
 	ret
 seto6:
 	lsl r16
 	rol r17
 	lsl r16
 	rol r17
 	ret
 seto7:
 	lsl r16
 	rol r17
 	lsl r16
 	rol r17
 	lsl r16
 	rol r17
 	ret
 seto8:
 	lsl r16
 	rol r17
 	lsl r16
 	rol r17
 	lsl r16
 	rol r17
 	lsl r16
 	rol r17
 	ret
 
 generate:
 	clr r17
 	cpi r18, 0b00
 	breq gen_pulse
 	cpi r18, 0b01
 	breq gen_triangle
 	cpi r18, 0b10
 	breq gen_saw
 	cpi r18, 0b11
 	breq gen_noise
 	ret
 
 gen_pulse:
 	cp r19, r21
 	brlo return
 	mov r17, r20
 	lsr r17
 	lsr r17
 return:
 	ret
 
 gen_triangle:
 	mov r17, r19
 	sbrc r19, 7
 	com r17
 	rjmp apply_volume
 	ret
 
 gen_saw:
 	mov r17, r19
 	lsr r17
 	lsr r17
 	rjmp apply_volume
 	ret
 
 gen_noise:
 	clr r21
 	clr r19
 	sbrc NOISEH, 6
 	ser r21
 	sbrc NOISEL, 3
 	ser r19
 	eor r19, r21
 	clr r21
 	lsl NOISEH
 	lsl NOISEL
 	adc NOISEH, r21
 	sbrc r19, 0
 	inc NOISEL
 	mov r17, NOISEL
 	lsr r17
 	rjmp apply_volume
 	ret
 
 apply_volume:
 	push r0
 	push r1
 
 	mul r17, r20
 	mov r17, r1
 
 	pop r1
 	pop r0
 
 	ret
 
 .dseg
 chan1_vol: .byte 1
 chan2_vol: .byte 1
 chan3_vol: .byte 1
 chan4_vol: .byte 1
 
 chan1_dut: .byte 1
 chan2_dut: .byte 1
 chan3_dut: .byte 1
 chan4_dut: .byte 1
 
 waveform: .byte 1
 enable: .byte 1
 
 tick_timer: .byte 1
 arp_timer: .byte 1
 slide_timer: .byte 1
 vibrato_timer: .byte 1
 
 note_on: .byte 1
 
 ; 0 - 3: note
 ; 4 - 7: octave
 ; 8 - 11: arp 1
 ; 12 - 15: arp 2
 chan1_notes: .byte 2
 chan2_notes: .byte 2
 chan3_notes: .byte 2
 chan4_notes: .byte 2
 
 chan1_tpit: .byte 2
 chan2_tpit: .byte 2
 chan3_tpit: .byte 2
 chan4_tpit: .byte 2
 
 chan1_tvol: .byte 1
 chan2_tvol: .byte 1
 chan3_tvol: .byte 1
 chan4_tvol: .byte 1
 
 chan1_tdut: .byte 1
 chan2_tdut: .byte 1
 chan3_tdut: .byte 1
 chan4_tdut: .byte 1
 
 ; 0 - down
 ; 1 - up
 vol_slide_dir: .byte 1
 pit_slide_dir: .byte 1
 
 chan1_vol_slide: .byte 1
 chan2_vol_slide: .byte 1
 chan3_vol_slide: .byte 1
 chan4_vol_slide: .byte 1
 
 chan1_pit_slide: .byte 1
 chan2_pit_slide: .byte 1
 chan3_pit_slide: .byte 1
 chan4_pit_slide: .byte 1
 
 chan1_port: .byte 1
 chan2_port: .byte 1
 chan3_port: .byte 1
 chan4_port: .byte 1
 
 ; 0 - 3: rate
 ; 4 - 7: depth
 chan1_vib: .byte 1
 chan2_vib: .byte 1
 chan3_vib: .byte 1
 chan4_vib: .byte 1
 
 chan1_trm: .byte 1
 chan2_trm: .byte 1
 chan3_trm: .byte 1
 chan4_trm: .byte 1
 
 chan1_pwm: .byte 1
 chan2_pwm: .byte 1
 chan3_pwm: .byte 1
 chan4_pwm: .byte 1
 
 chan1_pvib: .byte 2
 chan2_pvib: .byte 2
 chan3_pvib: .byte 2
 chan4_pvib: .byte 2
 
 chan1_ptrm: .byte 2
 chan2_ptrm: .byte 2
 chan3_ptrm: .byte 2
 chan4_ptrm: .byte 2
 
 chan1_tvib: .byte 1
 chan2_tvib: .byte 1
 chan3_tvib: .byte 1
 chan4_tvib: .byte 1
 
 chan1_ttrm: .byte 1
 chan2_ttrm: .byte 1
 chan3_ttrm: .byte 1
 chan4_ttrm: .byte 1
 
 chan1_tpwm: .byte 1
 chan2_tpwm: .byte 1
 chan3_tpwm: .byte 1
 chan4_tpwm: .byte 1
 
 ; 0 - 3: attack
 ; 4 - 7: decay
 ; 8 - 11: sustain
 ; 12 - 15: release
 chan1_env: .byte 2
 chan2_env: .byte 2
 chan3_env: .byte 2
 chan4_env: .byte 2
 
 chan1_fine: .byte 1
 chan2_fine: .byte 1
 chan3_fine: .byte 1
 chan4_fine: .byte 1