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OpenAudio_ArduinoLibrary/synth_sine_f32.cpp

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/*
* AudioSynthWaveformSine_F32
*
* Created: Chip Audette (OpenAudio) Feb 2017
* Modeled on: AudioSynthWaveformSine from Teensy Audio Library
*
* Purpose: Create sine wave of given amplitude and frequency
*
* License: MIT License. Use at your own risk.
*
*/
#include "synth_sine_f32.h"
#include "utility/dspinst.h"
// data_waveforms.c
extern "C" {
extern const int16_t AudioWaveformSine[257];
}
void AudioSynthWaveformSine_F32::update(void)
{
audio_block_f32_t *block;
uint32_t i, ph, inc, index, scale;
int32_t val1, val2;
if (magnitude) {
block = allocate_f32();
if (block) {
ph = phase_accumulator;
inc = phase_increment;
for (i=0; i < AUDIO_BLOCK_SAMPLES; i++) {
index = ph >> 24;
val1 = AudioWaveformSine[index];
val2 = AudioWaveformSine[index+1];
scale = (ph >> 8) & 0xFFFF;
val2 *= scale;
val1 *= 0x10000 - scale;
#if defined(KINETISK)
block->data[i] = (float) multiply_32x32_rshift32(val1 + val2, magnitude);
#elif defined(KINETISL)
block->data[i] = (float) ((((val1 + val2) >> 16) * magnitude) >> 16);
#endif
ph += inc;
block->data[i] = block->data[i] / 32768.0f; // scale to float
}
phase_accumulator = ph;
AudioStream_F32::transmit(block);
AudioStream_F32::release(block);
return;
}
}
phase_accumulator += phase_increment * AUDIO_BLOCK_SAMPLES;
}