#include "filter_moog.h"
#include "utility/dspinst.h"
#if defined(KINETISK)
void AudioFilterMoog::update_fixed(const int16_t *in,int16_t *lp)
{
const float MAX_INT = 32678.0;
for (int i = 0; i < AUDIO_BLOCK_SAMPLES; i++) {
float cs = (float)in[i]/MAX_INT;
lp[i] = (int16_t)cs*MAX_INT;
}
}
void AudioFilterMoog::update_variable(const int16_t *in,const int16_t *ctl, int16_t *lp)
{
const float MAX_INT = 32678.0;
for (int i = 0; i < AUDIO_BLOCK_SAMPLES; i++) {
float cs = (float)(in[i]/MAX_INT);
lp[i] =cs*MAX_INT;
}
}
void AudioFilterMoog::update(void)
{
audio_block_t *input_block=NULL, *control_block=NULL;
audio_block_t *lowpass_block=NULL;
input_block = receiveReadOnly(0);
control_block = receiveReadOnly(1);
if (!input_block) {
if (control_block) release(control_block);
return;
}
lowpass_block = allocate();
if (!lowpass_block) {
release(input_block);
if (control_block) release(control_block);
return;
}
if (control_block) {
update_variable(input_block->data, control_block->data, lowpass_block->data);
release(control_block);
} else {
update_fixed(input_block->data, lowpass_block->data);
}
release(input_block);
transmit(lowpass_block, 0);
release(lowpass_block);
return;
}
#elif defined(KINETISL)
void AudioFilterMoog::update(void)
{
audio_block_t *block;
block = receiveReadOnly(0);
if (block) release(block);
block = receiveReadOnly(1);
if (block) release(block);
}
#endif
Header:
#ifndef filter_moog_h_
#define filter_moog_h_
#include "Arduino.h"
#include "AudioStream.h"
class AudioFilterMoog: public AudioStream
{
float g;
float q;
float driv;
public:
AudioFilterMoog() : AudioStream(2, inputQueueArray) {
frequency(1000);
resonance(1);
drive(1);
}
void frequency(float freq) {
if (freq < 20.0) freq = 20.0;
else if (freq > AUDIO_SAMPLE_RATE_EXACT/2.5) freq = AUDIO_SAMPLE_RATE_EXACT/2.5;
g = 1 - expf(-2 * tanf(2 * M_PI * freq/(2 * AUDIO_SAMPLE_RATE_EXACT)));
}
void resonance(float qi) {
if (qi < 0.7) qi = 0.7;
else if (qi > 5.0) qi = 5.0;
q=qi;
}
void drive(float d) {
if (d > 10.0f) d = 10.0f;
if (d < 0.1f) d = 0.1f;
driv = d;
}
virtual void update(void);
private:
void update_fixed(const int16_t *in,int16_t *lp);
void update_variable(const int16_t *in, const int16_t *ctl, int16_t *lp);
audio_block_t *inputQueueArray[2];
};
#endif