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