C# Oscilator class¶
- Author or source: neotec
- Type: Sine, Saw, Variable Pulse, Triangle, C64 Noise
- Created: 2007-01-08 10:49:36
Parameters:
Pitch: The Osc's pitch in Cents [0 - 14399] startig at A -> 6.875Hz
Pulsewidth: [0 - 65535] -> 0% to 99.99%
Value: The last Output value, a set to this property 'syncs' the Oscilator
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 | public class SynthOscilator
{
public enum OscWaveformType
{
SAW, PULSE, TRI, NOISE, SINE
}
public int Pitch
{
get
{
return this._Pitch;
}
set
{
this._Pitch = this.MinMax(0, value, 14399);
this.OscStep = WaveSteps[this._Pitch];
}
}
public int PulseWidth
{
get
{
return this._PulseWidth;
}
set
{
this._PulseWidth = this.MinMax(0, value, 65535);
}
}
public OscWaveformType Waveform
{
get
{
return this._WaveForm;
}
set
{
this._WaveForm = value;
}
}
public int Value
{
get
{
return this._Value;
}
set
{
this._Value = 0;
this.OscNow = 0;
}
}
private int _Pitch;
private int _PulseWidth;
private int _Value;
private OscWaveformType _WaveForm;
private int OscNow;
private int OscStep;
private int ShiftRegister;
public const double BaseFrequence = 6.875;
public const int SampleRate = 44100;
public static int[] WaveSteps = new int[0];
public static int[] SineTable = new int[0];
public SynthOscilator()
{
if (WaveSteps.Length == 0)
this.CalcSteps();
if (SineTable.Length == 0)
this.CalcSine();
this._Pitch = 7200;
this._PulseWidth = 32768;
this._WaveForm = OscWaveformType.SAW;
this.ShiftRegister = 0x7ffff8;
this.OscNow = 0;
this.OscStep = WaveSteps[this._Pitch];
this._Value = 0;
}
private void CalcSteps()
{
WaveSteps = new int[14400];
for (int i = 0; i < 14400; i++)
{
double t0, t1, t2;
t0 = Math.Pow(2.0, (double)i / 1200.0);
t1 = BaseFrequence * t0;
t2 = (t1 * 65536.0) / (double)this.SampleRate;
WaveSteps[i] = (int)Math.Round(t2 * 4096.0);
}
}
private void CalcSine()
{
SineTable = new int[65536];
double s = Math.PI / 32768.0;
for (int i = 0; i < 65536; i++)
{
double v = Math.Sin((double)i * s) * 32768.0;
int t = (int)Math.Round(v) + 32768;
if (t < 0)
t = 0;
else if (t > 65535)
t = 65535;
SineTable[i] = t;
}
}
public override int Run()
{
int ret = 32768;
int osc = this.OscNow >> 12;
switch (this._WaveForm)
{
case OscWaveformType.SAW:
ret = osc;
break;
case OscWaveformType.PULSE:
if (osc < this.PulseWidth)
ret = 65535;
else
ret = 0;
break;
case OscWaveformType.TRI:
if (osc < 32768)
ret = osc << 1;
else
ret = 131071 - (osc << 1);
break;
case OscWaveformType.NOISE:
ret = ((this.ShiftRegister & 0x400000) >> 11) |
((this.ShiftRegister & 0x100000) >> 10) |
((this.ShiftRegister & 0x010000) >> 7) |
((this.ShiftRegister & 0x002000) >> 5) |
((this.ShiftRegister & 0x000800) >> 4) |
((this.ShiftRegister & 0x000080) >> 1) |
((this.ShiftRegister & 0x000010) << 1) |
((this.ShiftRegister & 0x000004) << 2);
ret <<= 4;
break;
case OscWaveformType.SINE:
ret = SynthTools.SineTable[osc];
break;
default:
break;
}
this.OscNow += this.OscStep;
if (this.OscNow > 0xfffffff)
{
int bit0 = ((this.ShiftRegister >> 22) ^ (this.ShiftRegister >> 17)) & 0x1;
this.ShiftRegister <<= 1;
this.ShiftRegister &= 0x7fffff;
this.ShiftRegister |= bit0;
}
this.OscNow &= 0xfffffff;
this._Value = ret - 32768;
return this._Value;
}
public int MinMax(int a, int b, int c)
{
if (b < a)
return a;
else if (b > c)
return c;
else
return b;
}
}
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