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115 lines
3.6 KiB
115 lines
3.6 KiB
/* Audio Library for Teensy 3.X
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* Copyright (c) 2014, Paul Stoffregen, paul@pjrc.com
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*
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* Development of this audio library was funded by PJRC.COM, LLC by sales of
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* Teensy and Audio Adaptor boards. Please support PJRC's efforts to develop
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* open source software by purchasing Teensy or other PJRC products.
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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, development funding notice, and this permission
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* notice shall be included in all 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
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* THE SOFTWARE.
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*/
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#include "filter_moog_f32.h"
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__inline__ float tanh_fast(float x)
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{
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// rational tanh aproximation
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float x2 = x * x;
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float a = x * (135135.0f + x2 * (17325.0f + x2 * (378.0f + x2)));
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float b = 135135.0f + x2 * (62370.0f + x2 * (3150.0f + x2 * 28.0f));
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return a / b;
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}
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#if defined(KINETISK)
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void AudioFilterMoog_F32::update_fixed(const float *in,float *lp)
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{
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for (int i = 0; i < 2*AUDIO_BLOCK_SAMPLES; i++) {
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float cs = tanh_fast(in[i/2] * driv);
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y_a = y_a + g * (tanh_fast(cs - q * ((y_d_1 + y_d)/2) - tanh_fast(y_a)));
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y_b = y_b + g * (tanh_fast(y_a) - tanh_fast(y_b));
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y_c = y_c + g * (tanh_fast(y_b) - tanh_fast(y_c));
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y_d_1 = y_d;
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y_d = y_d + g * (tanh_fast(y_c) - tanh_fast(y_d));
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lp[i/2] = y_d;
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}
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}
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void AudioFilterMoog_F32::update_variable(const float *in,const float *ctl, float *lp)
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{
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int over=2;
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float nf=basef*(exp2f(ctl[0/over]*oct));
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frequency(nf,false);
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for (int i = 0; i < 2*AUDIO_BLOCK_SAMPLES; i++) {
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float cs = tanh_fast(in[i/over] * driv);
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y_a = y_a + g * (tanh_fast(cs - q * ((y_d_1 + y_d)/2) - tanh_fast(y_a)));
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y_b = y_b + g * (tanh_fast(y_a) - tanh_fast(y_b));
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y_c = y_c + g * (tanh_fast(y_b) - tanh_fast(y_c));
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y_d_1 = y_d;
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y_d = y_d + g * (tanh_fast(y_c) - tanh_fast(y_d));
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lp[i/over] = y_d;
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}
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}
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void AudioFilterMoog_F32::update(void)
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{
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audio_block_f32_t *input_block=NULL, *control_block=NULL;
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audio_block_f32_t *lowpass_block=NULL;
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input_block = receiveReadOnly_f32(0);
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control_block = receiveReadOnly_f32(1);
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if (!input_block) {
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if (control_block) release(control_block);
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return;
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}
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lowpass_block = allocate_f32();
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if (!lowpass_block) {
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release(input_block);
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if (control_block) release(control_block);
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return;
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}
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if (control_block) {
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update_variable(input_block->data, control_block->data, lowpass_block->data);
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release(control_block);
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} else {
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update_fixed(input_block->data, lowpass_block->data);
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}
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AudioStream_F32::release(input_block);
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AudioStream_F32::transmit(lowpass_block, 0);
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AudioStream_F32::release(lowpass_block);
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return;
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}
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#elif defined(KINETISL)
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void AudioFilterMoog_F32::update(void)
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{
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audio_block_f32_t *block;
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block = receiveReadOnly_f32(0);
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if (block) AudioStream_F32::release(block);
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block = receiveReadOnly_f32(1);
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if (block) AudioStream_F32::release(block);
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}
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#endif
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