mirror of
https://github.com/sehugg/8bitworkshop.git
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118 lines
2.6 KiB
Plaintext
118 lines
2.6 KiB
Plaintext
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processor 6502
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include "vcs.h"
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include "macro.h"
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include "xmacro.h"
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seg.u Variables
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org $80
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Cycle0Lo byte
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Cycle1Lo byte
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Cycle2Lo byte
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Cycle3Lo byte
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Cycle0Hi byte
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Cycle1Hi byte
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Cycle2Hi byte
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Cycle3Hi byte
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Delta0Lo byte
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Delta1Lo byte
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Delta2Lo byte
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Delta3Lo byte
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Delta0Hi byte
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Delta1Hi byte
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Delta2Hi byte
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Delta3Hi byte
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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seg Code
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org $f000
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Start
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CLEAN_START
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lda #0
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sta Delta0Hi
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lda #137
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sta Delta0Lo
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lda #0
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sta Delta1Hi
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lda #172
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sta Delta1Lo
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lda #0
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sta Delta2Hi
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lda #217
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sta Delta2Lo
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lda #1
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sta Delta2Hi
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lda #273-256
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sta Delta2Lo
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NextFrame
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sta WSYNC
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jsr NextSamples
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jmp NextFrame
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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; Macro that mixes two software voices
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; and sets the volume for one TIA audio channel.
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; Usage: NEXTSAMPLEPAIR {audiochannel} {voice1} {voice2}
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MAC NEXTSAMPLEPAIR
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; Get first channel phase, put in X
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lda Cycle0Lo+{2}
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clc
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adc Delta0Lo+{2}
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sta Cycle0Lo+{2}
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lda Cycle0Hi+{2}
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adc Delta0Hi+{2}
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and #$1F
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sta Cycle0Hi+{2}
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tax
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; Get second channel phase, put in Y
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lda Cycle0Lo+{3}
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clc
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adc Delta0Lo+{3}
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sta Cycle0Lo+{3}
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lda Cycle0Hi+{3}
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adc Delta0Hi+{3}
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and #$1F
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sta Cycle0Hi+{3}
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tay
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; Lookup wavetable entry and sum
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lda Wavetable,y
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clc
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adc Wavetable,x
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; Divide by 2 and store to volume register
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lsr
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sta AUDV0+{1}
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ENDM
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NextSamples
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NEXTSAMPLEPAIR 0,0,1 ; mix voices 0 and 1
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NEXTSAMPLEPAIR 1,2,3 ; mix voices 2 and 3
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rts
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; 32-byte wavetable
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Wavetable
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hex 00010203 04050607 08090a0b 0c0d0e0f
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hex 0f0e0d0c 0b0a0908 07060504 03020100
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; Table of note periods
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align $100
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NoteDeltas
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word 9, 9, 10, 10, 11, 11, 12, 13, 14, 14, 15, 16
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word 17, 18, 19, 20, 22, 23, 24, 26, 27, 29, 30, 32
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word 34, 36, 38, 41, 43, 46, 48, 51, 54, 57, 61, 65
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word 68, 72, 77, 81, 86, 91, 97, 102, 108, 115, 122, 129
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word 137, 145, 153, 163, 172, 182, 193, 205, 217, 230, 244, 258
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word 273, 290, 307, 325, 344, 365, 387, 410, 434, 460, 487, 516
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word 547, 579, 614, 650, 689, 730, 773, 819, 868, 920, 974, 1032
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word 1093, 1159, 1227, 1300, 1378, 1460, 1546, 1638, 1736, 1839, 1948, 2064
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word 2187, 2317, 2455, 2601, 2755, 2919, 3093, 3277, 3472, 3678, 3897, 4128
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word 4374, 4634, 4910, 5202, 5511, 5839, 6186, 6554, 6943, 7356, 7793, 8257
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word 8748, 9268, 9819, 10403, 11022, 11677, 12371, 13107
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; Epilogue
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org $fffc
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.word Start
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.word Start
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