Noise.cpp

Go to the documentation of this file.

//
// Noise.cpp
//  See the copyright notice and acknowledgment of authors in the file COPYRIGHT
// 

#include "Noise.h"
#include <time.h>

using namespace csl;

///
/// Abstract Noise class
///

/// Constructors call UnitGenerator & Scalable constructors
/// Noise defaults to expansion copy policy (i.e. distinct noise per channel)
/// if no seed is specified, current clock time is used

Noise::Noise() : 
    UnitGenerator(), 
    Scalable(1.f, 0.f), 
    //mCopyPolicy(kExpand), 
    mSeed(time(NULL)), 
    mDivisor(1.0f / (float) 0x7fffffff) {
    setCopyPolicy(kExpand);
}

Noise::Noise(double ampl, double offset) : 
    UnitGenerator(), 
    Scalable((float)ampl, (float)offset), 
    //mCopyPolicy(kExpand), 
    mSeed(time(NULL)), 
    mDivisor(1.0f / (float) 0x7fffffff) {
    setCopyPolicy(kExpand);
}

Noise::Noise(int seed, double ampl, double offset) : 
    UnitGenerator(), 
    Scalable((float)ampl, (float)offset), 
    //mCopyPolicy(kExpand),
    mSeed(seed),
    mDivisor(1.0f / (float) 0x7fffffff) {
    setCopyPolicy(kExpand);
}

void Noise::dump() {
    logMsg("a Noise generator");
    Scalable::dump();
    UnitGenerator::dump();
}

///
/// White noise -- equal power per frequency
///

void WhiteNoise::nextBuffer(Buffer & outputBuffer, unsigned outBufNum) throw (CException) {
    sample* out = outputBuffer.buffer(outBufNum);   // get ptr to output channel
    unsigned numFrames = outputBuffer.mNumFrames;           // get buffer length

    DECLARE_SCALABLE_CONTROLS;              // declare the scale/offset buffers and values
    LOAD_SCALABLE_CONTROLS;
#ifdef CSL_DEBUG
    logMsg("WhiteNoise nextBuffer");
#endif          
    for (unsigned i = 0; i < numFrames; i++) {                  // sample loop  
        // call generate_random_number and do the division myself
        *out++ = ((((float) generateRandomNumber()) * mDivisor) * scaleValue) + offsetValue;        
        UPDATE_SCALABLE_CONTROLS;                           // update the dynamic scale/offset
    }
}

/// Most of this code was taken from an public domain C implementation written by Phil Burk.
/// The code and the webpage explaining it is at
///     http://www.firstpr.com.au/dsp/pink-noise/phil_burk_19990905mPatestmPink.c
/// and
///     http://www.firstpr.com.au/dsp/pink-noise/

PinkNoise::PinkNoise() : Noise() {
    setCopyPolicy(kExpand);
    initialize(32);
}

PinkNoise::PinkNoise(double ampl, double offset) : Noise(ampl, offset) {
    setCopyPolicy(kExpand);
    initialize(32);
}

PinkNoise::PinkNoise(int seed, double ampl, double offset) : Noise(seed, ampl, offset) {
    setCopyPolicy(kExpand);
    initialize(32);
}

/// Setup PinkNoise structure for N rows of generators.
void PinkNoise::initialize(int numRows) {
    int i;
    int pmax;
    mPinkIndex = 0;
    mPinkIndexMask = (1<<numRows) - 1;
            // Calculate maximum possible signed random value. Extra 1 for white noise always added.
    pmax = (numRows + 1) * (1<<(PINK_RANDOM_BITS-1));
    mPinkScalar = 1.0f / pmax;
            // Initialize rows.
    for (i=0; i<numRows; i++ ) mPinkRows[i] = 0;
        mPinkRunningSum = 0;
}

// Generate Pink noise values between -1.0 and +1.0
sample PinkNoise::nextPink() {
    int newRandom;
    int sum;
    sample output;
                // Increment and mask index.
    mPinkIndex = (mPinkIndex + 1) & mPinkIndexMask;
                // If index is zero, don't update any random values.
    if (mPinkIndex != 0 ) {
                // Determine how many trailing zeros in PinkIndex.
                // This algorithm will hang if n==0 so test first. 
        int numZeros = 0;
        int n = mPinkIndex;
        while((n & 1) == 0 ) {
            n = n >> 1;
            numZeros++;
        }
                // Replace the indexed ROWS random value.
                // Subtract and add back to RunningSum instead of adding all the random values together. Only one changes each time.
        mPinkRunningSum -= mPinkRows[numZeros];
        newRandom = ((int)generateRandomNumber()) >> PINK_RANDOM_SHIFT;
        mPinkRunningSum += newRandom;
        mPinkRows[numZeros] = newRandom;
    }
                // Add extra white noise value.
    newRandom = ((int)generateRandomNumber()) >> PINK_RANDOM_SHIFT;
    sum = mPinkRunningSum + newRandom;
                // Scale to range of -1.0 to 0.9999.
    output = mPinkScalar * sum;
//#define PINK_MEASURE
#ifdef PINK_MEASURE
                // Check Min/Max
    static float   pinkMax = 0, pinkMin = 0;
    if (output > pinkMax ) pinkMax = output;
    else if (output < pinkMin ) pinkMin = output;
//  printf("max: %g\t min: %g", pinkMax, pinkMin);
#endif
    return output;
}

void PinkNoise::nextBuffer(Buffer & outputBuffer, unsigned outBufNum) throw (CException) {
    SampleBuffer out = outputBuffer.buffer(outBufNum);
    unsigned numFrames = outputBuffer.mNumFrames;

    DECLARE_SCALABLE_CONTROLS;                          // declare the scale/offset buffers and values as above
#ifdef CSL_DEBUG
    logMsg("SineAsScaled nextBuffer");
#endif      
    LOAD_SCALABLE_CONTROLS; 
    for (unsigned i = 0; i < numFrames; i++ ) {
        *out++ = (nextPink() * scaleValue) + offsetValue;       // get a sample
        UPDATE_SCALABLE_CONTROLS;
    }
}