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104 lines
4.3 KiB
104 lines
4.3 KiB
/* synth_sin_cos_f32.cpp
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*
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* SynthSinCos_F32 Bob Larkin April 17, 2020
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*
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* Based on Chip Audette's OpenAudio sine(), that was
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* Modeled on: AudioSynthWaveformSine from Teensy Audio Library
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*
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* Purpose: Create sine and cosine wave of given amplitude, frequency
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* and phase. Outputs in float32_t floating point.
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* Routines are from the arm CMSIS library and use a 512 point lookup
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* table with linear interpolation to achieve float accuracy limits.
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*
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* Copyright (c) 2020 Bob Larkin
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in all
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* copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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// Rev 10 March 2021 - Corrected interpolation formula Bob L
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#include "synth_sin_cos_f32.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 AudioSynthSineCosine_F32::update(void) {
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audio_block_f32_t *blockS, *blockC;
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uint16_t index, i;
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float32_t a, b, deltaPhase, phaseC;
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blockS = AudioStream_F32::allocate_f32(); // Output blocks
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if (!blockS) return;
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blockC = AudioStream_F32::allocate_f32();
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if (!blockC) {
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AudioStream_F32::release(blockS);
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return;
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}
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// doSimple has amplitude (-1, 1) and sin/cos differ by 90.00 degrees.
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if (doSimple) {
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for (i=0; i < block_length; i++) {
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phaseS += phaseIncrement;
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if (phaseS > 512.0f)
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phaseS -= 512.0f;
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index = (uint16_t) phaseS;
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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] = a + 0.001953125*(b-a)*deltaPhase; /* Linear interpolation process */
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/* Repeat for cosine by adding 90 degrees phase */
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index = (index + 128) & 0x01ff;
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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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/* deltaPhase will be the same as used for sin */
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blockC->data[i] = a + 0.001953125*(b-a)*deltaPhase; /* Linear interpolation process */
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}
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}
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else { // Do a more flexible update, i.e., not doSimple
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for (i=0; i < block_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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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] = amplitude_pk*(a + 0.001953125*(b-a)*deltaPhase); /* Linear interpolation process */
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/* Shift forward phaseS_C and get cos. First, the calculation of index of the table */
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phaseC = phaseS + phaseS_C;
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if (phaseC > 512.0f) phaseC -= 512.0f;
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index = (uint16_t) phaseC;
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deltaPhase = phaseC -(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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blockC->data[i] = amplitude_pk*(a + 0.001953125*(b-a)*deltaPhase); /* Linear interpolation process */
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}
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}
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AudioStream_F32::transmit(blockS, 0);
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AudioStream_F32::release (blockS);
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AudioStream_F32::transmit(blockC, 1);
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AudioStream_F32::release (blockC);
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return;
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}
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