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42 lines
1.4 KiB
42 lines
1.4 KiB
/*
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* AudioSynthWaveformSine_F32
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*
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* Created: Chip Audette (OpenAudio) Feb 2017
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* Modeled on: AudioSynthWaveformSine from Teensy Audio Library
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*
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* Purpose: Create sine wave of given amplitude and frequency
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*
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* License: MIT License. Use at your own risk.
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*
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* Revised per synth_sine_f32.h. 7 Feb 2022 Bob.
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*/
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#include "synth_sine_f32.h"
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#include "utility/dspinst.h"
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// 513 values of the sine wave in a float array:
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#include "sinTable512_f32.h"
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void AudioSynthWaveformSine_F32::update(void) {
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audio_block_f32_t *blockS;
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uint16_t index, i;
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float32_t a, b;
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blockS = AudioStream_F32::allocate_f32(); // Output blocks
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if (!blockS) return;
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for (i=0; i < blockS->length; i++) {
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phaseS += phaseIncrement;
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if (phaseS > 512.0f) phaseS -= 512.0f;
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index = (uint16_t) phaseS;
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float32_t deltaPhase = phaseS - (float32_t)index;
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/* Read two nearest values of input value from the sin table */
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a = sinTable512_f32[index];
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b = sinTable512_f32[index+1];
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blockS->data[i] = magnitude*(a+(b-a)*deltaPhase); // Linear interpolation
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}
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// For higher frequencies, an optional bandpass filter the output
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// This does a pass through for lower frequencies
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if(doPureSpectrum)
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arm_biquad_cascade_df1_f32(&bq_inst, blockS->data, blockS->data, 128);
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AudioStream_F32::transmit(blockS);
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AudioStream_F32::release (blockS);
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}
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