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8bitworkshop/presets/c64/sidmacros.h

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// SID voices are v1, v2, v3
// wave options flags
#define SID_GATE 0x01
#define SID_SYNC 0x02
#define SID_RINGMOD 0x04
#define SID_TESTBIT 0x08
#define SID_TRIANGLE 0x10
#define SID_SAWTOOTH 0x20
#define SID_SQUARE 0x40
#define SID_NOISE 0x80
// Init SID global volume
// volume: 0-15
// filters: bitmask
#define SID_INIT(volume, filters) \
SID.amp = (volume) | ((filters)<<4);
// stop voice
#define SID_STOP(voice) \
SID.voice.ctrl &= ~SID_GATE;
// start voice
#define SID_START(voice) \
SID.voice.ctrl |= SID_GATE;
// set ADSR envelope
#define SID_ADSR(voice,attack,decay,sustain,release) \
SID.voice.ad = ((decay)&15) | ((attack)<<4); \
SID.voice.sr = ((release)&15) | ((sustain)<<4);
// set frequency (0 - 65535)
#define SID_FREQ(voice,_freq) \
SID.voice.freq = (_freq);
// set pulse width (0 - 4095)
#define SID_PULSEWIDTH(voice,_pw) \
SID.voice.pw = (_pw);
// set wave shape and options
#define SID_WAVE(voice,options) \
SID.voice.ctrl = (SID.voice.ctrl & 1) | (options)
// play a quick square wave pulse
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#define SID_PULSE_DECAY(voice, freq) \
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SID_STOP(voice) \
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SID_FREQ(voice,freq); \
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SID_PULSEWIDTH(voice,0x200); \
SID_ADSR(voice,8,8,0,4); \
SID_WAVE(voice,SID_SQUARE|SID_GATE); \
// play a tone if one is not already playing
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#define SID_PLAY_TONE(freq) \
if (!SID.read3) { SID_PULSE_DECAY(v3, (freq)) }