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91 lines
3.1 KiB
91 lines
3.1 KiB
/*
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* synth_GaussianWhiteNoise_F32.cpp
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* by Bob Larkin W7PUA 15 June 2020
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*
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* Created: Chip Audette, OpenAudio, Feb 2017
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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 "synth_GaussianWhiteNoise_F32.h"
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// Park-Miller-Carta Pseudo-Random Number Generator
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// http://www.firstpr.com.au/dsp/rand31/
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void AudioSynthGaussian_F32::update(void)
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{
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audio_block_f32_t *blockOut;
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uint32_t it;
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float32_t rdev = 0.0f;
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float32_t* pd;
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if (sd < 0.01f) {
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return; // Not enabled
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}
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#if TEST_TIME_GWN
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if (iitt++ >1000000) iitt = -10;
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uint32_t t1, t2;
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t1 = tElapse;
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#endif
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blockOut = AudioStream_F32::allocate_f32();
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if (!blockOut) {
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if(errorPrint) Serial.println("GWN-ERR: No output memory");
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return;
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}
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pd = &blockOut->data[0]; // Pointer to write data
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/* The "Even Quicker" uniform random sample generator from D. E. Knuth and
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* H. W. Lewis and described in Chapter 7 of "Numerical Receipes in C",
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* 2nd ed, with the comment "this is about as good as any 32-bit linear
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* congruential generator, entirely adequate for many uses."
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*/
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union {
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uint32_t i32;
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float32_t f32;
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} uinf;
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for(int i=0; i<blockSize; i++) {
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rdev = 0.0f;
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for (int j=0; j<12; j++){ // Add 12, using Central Limit to get Gaussian
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idum = (uint32_t)1664525 * idum + (uint32_t)1013904223;
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it = FL_ONE | (FL_MASK & idum); // Generate random number
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/* dev += (*(float *)&it) - 1.0f; // Cute convert to float, but gets compiler warning */
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uinf.i32 = it;
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rdev += uinf.f32 - 1.0f;
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}
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// Next, to get general form
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// return mu + sd * 3.4641016f * (rdev - 0.5*(float)M) / sqrtf((float32_t)M);
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*pd++ = sd*(rdev - 6.0f); // Specific for mu=0.0, M=12
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}
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AudioStream_F32::transmit(blockOut);
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AudioStream_F32::release(blockOut);
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#if TEST_TIME_GWN
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t2 = tElapse;
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if(iitt++ < 0) {
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Serial.print("At Gaussian Noise end, microseconds = ");
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Serial.println (t2 - t1);
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}
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t1 = tElapse;
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#endif
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}
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