annotate projects/d-box/PinkNoise.h @ 45:579c86316008 newapi

Major API overhaul. Moved to a single data structure for handling render functions. Functionally, generally similar except for scheduling within PRU loop function, which now uses interrupts from the PRU rather than polling. This requires an updated kernel.

#ifndef _PinkNoise_H
#define _PinkNoise_H

// Technique by Larry "RidgeRat" Trammell 3/2006
// http://home.earthlink.net/~ltrammell/tech/pinkalg.htm
// implementation and optimization by David Lowenfels

#include <cstdlib>
#include <ctime>
#include <stdlib.h>

#define PINK_NOISE_NUM_STAGES 3

class PinkNoise {
public:
  PinkNoise() {
  srand ( time(NULL) ); // initialize random generator
    clear();
  }

  void clear() {
    for( size_t i=0; i< PINK_NOISE_NUM_STAGES; i++ )
      state[ i ] = 0.0;
    }

  float tick() {
    static const float RMI2 = 2.0 / float(RAND_MAX); // + 1.0; // change for range [0,1)
    static const float offset = A[0] + A[1] + A[2];

  // unrolled loop
    float temp = float( rand() );
    state[0] = P[0] * (state[0] - temp) + temp;
    temp = float( rand() );
    state[1] = P[1] * (state[1] - temp) + temp;
    temp = float( rand() );
    state[2] = P[2] * (state[2] - temp) + temp;
    return ( A[0]*state[0] + A[1]*state[1] + A[2]*state[2] )*RMI2 - offset;
  }

protected:
  float state[ PINK_NOISE_NUM_STAGES ];
  static const float A[ PINK_NOISE_NUM_STAGES ];
  static const float P[ PINK_NOISE_NUM_STAGES ];
};

//const float PinkNoise::A[] = { 0.02109238, 0.07113478, 0.68873558 }; // rescaled by (1+P)/(1-P)
//const float PinkNoise::P[] = { 0.3190,  0.7756,  0.9613  };

#endif