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43 lines
1.0 KiB
ArmAsm
43 lines
1.0 KiB
ArmAsm
;
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; Mariano Domínguez
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; 2022-12-4
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;
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; atari lib
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;
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.include "atari.inc"
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.export _sound
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.import popa
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; play sound, arguments: voice, pitch, distortion, volume. same as BASIC
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.proc _sound
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sta STORE2 ;save volume
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jsr popa ;get distortion
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sta STORE1 ;save distortion
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jsr popa ;get pitch
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pha ;save in stack
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jsr popa ;get voice
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asl a ;adjust voice *2 for offset in x
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tax
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pla ;get pitch from stack
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sta AUDF1,x ; store pitch
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lda #0
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sta AUDCTL
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lda #3
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stx SKCTL ; init sound
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lda STORE1 ;get distortion
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asl a ;ignore the high nibble
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asl a
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asl a
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asl a
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clc ; setup for adding volume
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adc STORE2 ; add volume
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sta AUDC1,x ; volume + distortion in control channel
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rts
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.endproc
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; reserve 2 bytes for temp storage
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.bss
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STORE1: .res 1
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STORE2: .res 1 |