tracker6: make it interrupt-run
This commit is contained in:
Vince Weaver
parent
28fb6d13ba
commit
27516de7f9
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@ -37,7 +37,8 @@ d4.o: d4.s \
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zp.inc hardware.inc \
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mA2E_4.s \
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mockingboard_init.s play_frame.s \
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tracker_init.s ay3_write_regs.s
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tracker_init.s ay3_write_regs.s interrupt_handler.s \
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mockingboard_constants.s
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ca65 -o d4.o d4.s -l d4.lst
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@ -53,4 +54,4 @@ text_to_tiny.o: text_to_tiny.c
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####
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clean:
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rm -f *~ *.o *.lst D2 HELLO text_to_tiny mA2E_2.s mA2E_3.s mA2E_4.s
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rm -f *~ *.o *.lst D4 HELLO text_to_tiny mA2E_2.s mA2E_3.s mA2E_4.s
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@ -6,21 +6,8 @@
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.include "zp.inc"
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.include "hardware.inc"
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; for a 256 entry we need to fit in 252 bytes
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; 310 bytes -- initial
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; 268 bytes -- strip out interrupts
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; 262 bytes -- simplify init
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; 261 bytes -- optimize init more
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; 253 bytes -- optimize var init
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; 252 bytes -- bne vs jmp
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; 250 bytes -- song only has 16 notes so can never be negative
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; 249 bytes -- make terminating value $80 instead of $FF
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; 247 bytes -- combine note loop. makes song a bit faster
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; 245 bytes -- try to optimize writing out volume
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; 255 bytes -- add in some visualization
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; 252 bytes -- re-arrange decode code
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d2:
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d4:
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;===================
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; music Player Setup
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@ -37,26 +24,14 @@ tracker_song = peasant_song
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jsr SETGR ; enable lo-res graphics
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cli ; enable music
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game_loop:
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; typically A=0, X=FF, Y=0 here
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; play a frame of music
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.include "play_frame.s"
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.include "ay3_write_regs.s"
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jmp game_loop
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; delay 20Hz, or 1/20s = 50ms
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lda #140
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jsr WAIT
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lda #140
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jsr WAIT
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lda #140
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jsr WAIT
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beq game_loop
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.include "interrupt_handler.s"
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.include "mockingboard_constants.s"
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; music
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.include "mA2E_4.s"
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@ -0,0 +1,68 @@
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;================================
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;================================
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; mockingboard interrupt handler
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;================================
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;================================
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; On Apple II/6502 the interrupt handler jumps to address in 0xfffe
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; This is in the ROM, which saves the registers
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; on older IIe it saved A to $45 (which could mess with DISK II)
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; newer IIe doesn't do that.
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; It then calculates if it is a BRK or not (which trashes A)
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; Then it sets up the stack like an interrupt and calls 0x3fe
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; Note: the IIc is much more complicated
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; its firmware tries to decode the proper source
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; based on various things, including screen hole values
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; we bypass that by switching out ROM and replacing the
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; $fffe vector with this, but that does mean we have
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; to be sure status flag and accumulator set properly
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interrupt_handler:
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php ; save status flags
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cld ; clear decimal mode
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pha ; save A ; 3
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; A is saved in $45 by firmware
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txa
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pha ; save X
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tya
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pha ; save Y
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inc $0404 ; debug (flashes char onscreen)
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ay3_irq_handler:
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bit MOCK_6522_T1CL ; clear 6522 interrupt by reading T1C-L ; 4
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.include "play_frame.s"
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.include "ay3_write_regs.s"
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;=================================
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; Finally done with this interrupt
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;=================================
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done_ay3_irq_handler:
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pla
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tay ; restore Y
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pla
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tax ; restore X
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pla ; restore a ; 4
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; on II+/IIe (but not IIc) we need to do this?
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interrupt_smc:
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lda $45 ; restore A
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plp ; restore flags
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rti ; return from interrupt ; 6
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;============
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; typical
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; ???? cycles
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@ -0,0 +1,21 @@
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init_addresses:
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.byte <MOCK_6522_DDRB1,<MOCK_6522_DDRA1 ; set the data direction for all pins of PortA/PortB to be output
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.byte <MOCK_6522_ACR,<MOCK_6522_IER ; Continuous interrupts, clear all interrupts
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.byte <MOCK_6522_IFR,<MOCK_6522_IER ; enable interrupt on timer overflow
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.byte <MOCK_6522_T1CL,<MOCK_6522_T1CH ; set oflow value, start counting
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.byte <MOCK_6522_ORB1,<MOCK_6522_ORB1 ; reset ay-3-8910
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; note, terminated by the $ff below
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init_values:
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.byte $ff,$ff ; set the data direction for all pins of PortA/PortB to be output
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.byte $40,$7f
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.byte $C0,$C0
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.byte $e7,$4f ; c7ce / 1.023e6 = .050s, 20Hz
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.byte MOCK_AY_RESET,MOCK_AY_INACTIVE
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; c7ce / 1.023e6 = .050s, 20Hz
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; 9c40 / 1.023e6 = .040s, 25Hz
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; 4fe7 / 1.023e6 = .020s, 50Hz
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; 411a / 1.023e6 = .016s, 60Hz
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@ -66,12 +66,54 @@ mockingboard_init:
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; Reset Left AY-3-8910
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;===========================
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ldx #$FF
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stx MOCK_6522_DDRB1
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stx MOCK_6522_DDRA1
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; ldx #$FF
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; stx MOCK_6522_DDRB1
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; stx MOCK_6522_DDRA1
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inx ; #MOCK_AY_RESET $0
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stx MOCK_6522_ORB1
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ldx #MOCK_AY_INACTIVE ; $4
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stx MOCK_6522_ORB1
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; inx ; #MOCK_AY_RESET $0
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; stx MOCK_6522_ORB1
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; ldx #MOCK_AY_INACTIVE ; $4
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; stx MOCK_6522_ORB1
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; sei ; disable interrupts, is this necessary?
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;=========================
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; Setup Interrupt Handler
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;=========================
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; NOTE: we don't support IIc as it's a hack
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; traditionally Mockingboard on IIc was rare
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;========================
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; set up interrupt
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; Vector address goes to 0x3fe/0x3ff
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; can save 10 bytes if we load in memory so this
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; is in the right place automatically
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lda #<interrupt_handler ; 2
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sta $03fe ; 3
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lda #>interrupt_handler ; 2
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sta $03ff ; 3
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;=========
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; 10
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;=========================
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; Initialize the 6522s
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; Reset Left AY-3-8910
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;===========================
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; entries=10
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; 14 + 2*entries = 34 bytes
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; assume Y=0 on entry?
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ldy #0 ; 2
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init_it_loop:
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lda init_values,Y ; 3
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ldx init_addresses,Y ; 3
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bmi doneit ; 2
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iny ; 1
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sta $c400,X ; 3
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bne init_it_loop ; 2
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doneit:
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@ -3,6 +3,15 @@ play_frame:
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;============================
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; see if still counting down
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lda SONG_COUNTDOWN
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; rotate through channel A volume
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tya
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and #$7
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tay
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lda channel_a_volume,Y
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sta AY_REGS+8
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lda SONG_COUNTDOWN
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bpl done_update_song
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@ -17,9 +26,8 @@ set_notes_loop:
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;==================
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; see if hit end
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; this song only 16 notes so valid notes always positive
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; cmp #$80
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bpl not_end
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cmp #$ff
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bne not_end
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;====================================
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; if at end, loop back to beginning
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@ -30,14 +38,15 @@ set_notes_loop:
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not_end:
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; NNNNNNEC -- c=channel, e=end, n=note
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pha ; save note
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and #1
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tax
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ldy #$0E
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sty AY_REGS+8,X ; $08 set volume A,B
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; tax
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; ldy #$0E
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; sty AY_REGS+8,X ; $08 set volume A,B
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asl
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tax ; put channel offset in X
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@ -46,6 +55,9 @@ not_end:
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pla ; restore note
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tay
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and #$2
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asl
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asl
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asl
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sta SONG_COUNTDOWN ; always 2 long?
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tya
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@ -76,3 +88,9 @@ blah_urgh:
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done_update_song:
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dec SONG_COUNTDOWN
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bmi set_notes_loop
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bpl skip_data
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channel_a_volume:
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.byte 14,14,14,14,11,11,10,10
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skip_data:
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