Sine

Sine AudioSDK

code + comments:

 // Geinterpoleerde Wavetable osc 4 AudioSDK
 // Jorn Lemon 31-3-2004 www.twistedlemon.nl

 class osc
 {
 protected:
 public:
 	osc(int samplerate)
 	sin_osc(float &output, double freq);
 	sin_LFO(float &output, double freq);
 	sin_FM(float &output, double freq, float mod_index);
 	double *wave;
 	/*static */
 	double phase, phase1, phase2;
 	int i;
 	double rest;
 	int ndx;
 	double TWOPIE, STEP;
 };
 
 osc::osc(int samplerate)
 {
 	TWOPIE = 8.0*atan(1.0);
 	STEP = TWOPIE/samplerate;
 	wave = new float[2049];
 	phase1, phase = 0.0;
 	wstep = 2048.0/samplerate;
 	for(i=0;i<2049;i++)	wave[i] = sin(TWOPIE*i/2048.0);
 }

 osc::sin_LFO(float &output, double freq)
 {	// a very simple sinwave oscillator, better for LFO
 	output = sin(phase);
 	//	increment the phase
 	phase += freq*STEP;
 }
 
 osc::sin_FM(float &output, double freq, float modulator, float mod_index)
 {	// FM voice modulator, carrier.
 	output = sin(phase1 + mod_index*freq*STEP*modulator);	    	// the output FM
   	// increment the phase
 	phase1 += freq*STEP; 
 }

 osc::sin_osc(float &output, double freq)
 {	// wave table oscilator
 	phase += freq * wstep;
 	while(phase >= 2048.0)	phase -= 2048.0;
 	while(phase < 0.0)		phase += 2048.0;
 
 	ndx = int(phase);
 	rest = phase - ndx;
 
 	output = wave[ndx] + rest*(wave[ndx+1] - wave[ndx]);	  	// interpolate
 }