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125 lines
2.2 KiB
ArmAsm
125 lines
2.2 KiB
ArmAsm
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; Sound driver for the Atari Lynx.
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;
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; Karri Kaksonen and Bjoern Spruck, 11.12.2012
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;
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.include "lynx.inc"
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.include "zeropage.inc"
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.export _lynx_snd_init
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;----------------------------------------------------------------------------
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; ZP variables that go into APPZP
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;
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.segment "APPZP" : zeropage
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SndSema: .res 1
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SndPtrTmp: .res 2
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SndTmp: .res 2
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SndEnvPtr: .res 2
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;----------------------------------------------------------------------------
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; Global variables
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;
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.bss
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SndRetAFlag2: .res 1
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SndRetAFlag: .res 1
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SndPtrLo: .res 4
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SndPtrHi: .res 4
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SndDelay: .res 4
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SndLoopCnt: .res 4
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SndLoopPtrLo: .res 4
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SndLoopPtrHi: .res 4
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SndVolume: .res 4
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SndMaxVolume: .res 4
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SndNotePlaying: .res 4
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SndRetAddr: .res 8
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SndActive: .res 4
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SndReqStop: .res 4
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SndEnvVol: .res 4
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SndEnvFrq: .res 4
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SndEnvWave: .res 4
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SndChannel: .res 32
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SndEnvVolCnt: .res 4
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SndEnvVolInc: .res 4
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SndEnvVolOff: .res 4
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SndEnvVolLoop: .res 4
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SndEnvVolParts: .res 4
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SndEnvVolParts2: .res 4
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SndEnvFrqCnt: .res 4
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SndEnvFrqInc: .res 4
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SndEnvFrqOff: .res 4
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SndEnvFrqLoop: .res 4
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SndEnvFrqParts: .res 4
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SndEnvFrqParts2: .res 4
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SndEnvWaveCnt: .res 4
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SndEnvWaveOff: .res 4
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SndEnvWaveLoop: .res 4
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SndEnvWaveParts: .res 4
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SndEnvWaveParts2: .res 4
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MAX_INSTRUMENTS .set 64
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SndEnvVolPtrLo: .res MAX_INSTRUMENTS
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SndEnvVolPtrHi: .res MAX_INSTRUMENTS
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SndEnvFrqPtrLo: .res MAX_INSTRUMENTS
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SndEnvFrqPtrHi: .res MAX_INSTRUMENTS
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SndEnvWavePtrLo: .res MAX_INSTRUMENTS
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SndEnvWavePtrHi: .res MAX_INSTRUMENTS
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.rodata
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SndOffsets: .byte $00,$08,$10,$18
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.code
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;----------------------------------------------------------------------------
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; void lynx_snd_init() will initialize the sound engine.
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;
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_31250Hz .set %101
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_lynx_snd_init:
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php
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sei
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lda #%10011000|_31250Hz
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sta STIMCTLA
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lda #129
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sta STIMBKUP ; set up a 240Hz IRQ
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stz AUD0VOL
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stz AUD1VOL
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stz AUD2VOL
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stz AUD3VOL
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stz $fd44 ; all channels full volume / no attenuation
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lda #$ff
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stz MSTEREO
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lda #0
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sta AUD0CTLA
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sta AUD1CTLA
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sta AUD2CTLA
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sta AUD3CTLA
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ldx #3
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lda #0
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init0: stz SndActive,x
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stz SndReqStop,x
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stz SndEnvVol,x
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stz SndEnvFrq,x
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stz SndEnvWave,x
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ldy SndOffsets,x
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sta SndChannel+2,y
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dex
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bpl init0
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stz SndRetAFlag
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stz SndRetAFlag2
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stz SndSema
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plp
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rts
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