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OpenAudio_ArduinoLibrary/synth_GaussianWhiteNoise_F3...

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/*
* synth_GaussianWhiteNoise_F32.cpp
* by Bob Larkin W7PUA 15 June 2020
*
* Created: Chip Audette, OpenAudio, Feb 2017
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice, development funding notice, and this permission
* notice shall be included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "synth_GaussianWhiteNoise_F32.h"
// Park-Miller-Carta Pseudo-Random Number Generator
// http://www.firstpr.com.au/dsp/rand31/
void AudioSynthGaussian_F32::update(void)
{
audio_block_f32_t *blockOut;
uint32_t it;
float32_t rdev = 0.0f;
float32_t* pd;
if (sd < 0.01f) {
return; // Not enabled
}
#if TEST_TIME_GWN
if (iitt++ >1000000) iitt = -10;
uint32_t t1, t2;
t1 = tElapse;
#endif
blockOut = AudioStream_F32::allocate_f32();
if (!blockOut) {
if(errorPrint) Serial.println("GWN-ERR: No output memory");
return;
}
pd = &blockOut->data[0]; // Pointer to write data
/* The "Even Quicker" uniform random sample generator from D. E. Knuth and
* H. W. Lewis and described in Chapter 7 of "Numerical Receipes in C",
* 2nd ed, with the comment "this is about as good as any 32-bit linear
* congruential generator, entirely adequate for many uses."
*/
union {
uint32_t i32;
float32_t f32;
} uinf;
for(int i=0; i<blockSize; i++) {
rdev = 0.0f;
for (int j=0; j<12; j++){ // Add 12, using Central Limit to get Gaussian
idum = (uint32_t)1664525 * idum + (uint32_t)1013904223;
it = FL_ONE | (FL_MASK & idum); // Generate random number
/* dev += (*(float *)&it) - 1.0f; // Cute convert to float, but gets compiler warning */
uinf.i32 = it;
rdev += uinf.f32 - 1.0f;
}
// Next, to get general form
// return mu + sd * 3.4641016f * (rdev - 0.5*(float)M) / sqrtf((float32_t)M);
*pd++ = sd*(rdev - 6.0f); // Specific for mu=0.0, M=12
}
AudioStream_F32::transmit(blockOut);
AudioStream_F32::release(blockOut);
#if TEST_TIME_GWN
t2 = tElapse;
if(iitt++ < 0) {
Serial.print("At Gaussian Noise end, microseconds = ");
Serial.println (t2 - t1);
}
t1 = tElapse;
#endif
}