/*-----------------------------------------------------------------------------
* Sets the frequency of sinus oscillator.
*
* @param mod pointer on modulator structure.
* @param freq frequency of the oscillator in Hz.
* @param sample_rate sample rate on audio output in Hz.
* @param phase initial phase of the oscillator in degree (0 to 360).
* -----------------------------------------------------------------------------*/
void set_sinus_frequency(sinus_modulator mod, float freq, float sample_rate, float phase)
{
float w = 2f * Mathf.PI * freq / sample_rate; /* initial angle */
float a;
mod.a1 = 2f * Mathf.Cos(w);
a = (2f * Mathf.PI / 360f) * phase;
mod.buffer2 = Mathf.Sin(a - w); /* y(n-1) = sin(-intial angle) */
mod.buffer1 = Mathf.Sin(a); /* y(n) = sin(initial phase) */
mod.reset_buffer2 = Mathf.Sin(Mathf.PI / 2f - w); /* reset value for PI/2 */
}
/*-----------------------------------------------------------------------------
* Gets current value of sinus modulator:
* y(n) = a1 . y(n-1) - y(n-2)
* out = a1 . buffer1 - buffer2
*
* @param pointer on modulator structure.
* @return current value of the modulator sine wave.
* -----------------------------------------------------------------------------*/
float get_mod_sinus(sinus_modulator mod)
{
float outp;
outp = mod.a1 * mod.buffer1 - mod.buffer2;
mod.buffer2 = mod.buffer1;
if (outp >= 1.0f) /* reset in case of instability near PI/2 */
{
outp = 1.0f; /* forces output to the right value */
mod.buffer2 = mod.reset_buffer2;
}
if (outp <= -1.0f) /* reset in case of instability near -PI/2 */
{
outp = -1.0f; /* forces output to the right value */
mod.buffer2 = -mod.reset_buffer2;
}
mod.buffer1 = outp;
return(outp);
}
public modulator()
{
sinus = new sinus_modulator();
triang = new triang_modulator();
}
