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/*
* $Id: patest_pink.c,v 1.1.1.1 2002/01/22 00:52:36 phil Exp $
patest_pink.c
Generate Pink Noise using Gardner method.
Optimization suggested by James McCartney uses a tree
to select which random value to replace.
x x x x x x x x x x x x x x x x
x x x x x x x x
x x x x
x x
x
Tree is generated by counting trailing zeros in an increasing index.
When the index is zero, no random number is selected.
*
* Author: Phil Burk http://www.softsynth.com
*
* This program uses the PortAudio Portable Audio Library.
* For more information see: http://www.portaudio.com
* Copyright (c) 1999-2000 Ross Bencina and Phil Burk
*
* 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 and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* Any person wishing to distribute modifications to the Software is
* requested to send the modifications to the original developer so that
* they can be incorporated into the canonical version.
*
* 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 <stdio.h>
#include <math.h>
#include "portaudio.h"
#define PINK_MAX_RANDOM_ROWS (30)
#define PINK_RANDOM_BITS (24)
#define PINK_RANDOM_SHIFT ((sizeof(long)*8)-PINK_RANDOM_BITS)
typedef struct
{
long pink_Rows[PINK_MAX_RANDOM_ROWS];
long pink_RunningSum; /* Used to optimize summing of generators. */
int pink_Index; /* Incremented each sample. */
int pink_IndexMask; /* Index wrapped by ANDing with this mask. */
float pink_Scalar; /* Used to scale within range of -1.0 to +1.0 */
}
PinkNoise;
/* Prototypes */
static unsigned long GenerateRandomNumber( void );
void InitializePinkNoise( PinkNoise *pink, int numRows );
float GeneratePinkNoise( PinkNoise *pink );
/************************************************************/
/* Calculate pseudo-random 32 bit number based on linear congruential method. */
static unsigned long GenerateRandomNumber( void )
{
/* Change this seed for different random sequences. */
static unsigned long randSeed = 22222;
randSeed = (randSeed * 196314165) + 907633515;
return randSeed;
}
/************************************************************/
/* Setup PinkNoise structure for N rows of generators. */
void InitializePinkNoise( PinkNoise *pink, int numRows )
{
int i;
long pmax;
pink->pink_Index = 0;
pink->pink_IndexMask = (1<<numRows) - 1;
/* Calculate maximum possible signed random value. Extra 1 for white noise always added. */
pmax = (numRows + 1) * (1<<(PINK_RANDOM_BITS-1));
pink->pink_Scalar = 1.0f / pmax;
/* Initialize rows. */
for( i=0; i<numRows; i++ ) pink->pink_Rows[i] = 0;
pink->pink_RunningSum = 0;
}
#define PINK_MEASURE
#ifdef PINK_MEASURE
float pinkMax = -999.0;
float pinkMin = 999.0;
#endif
/* Generate Pink noise values between -1.0 and +1.0 */
float GeneratePinkNoise( PinkNoise *pink )
{
long newRandom;
long sum;
float output;
/* Increment and mask index. */
pink->pink_Index = (pink->pink_Index + 1) & pink->pink_IndexMask;
/* If index is zero, don't update any random values. */
if( pink->pink_Index != 0 )
{
/* Determine how many trailing zeros in PinkIndex. */
/* This algorithm will hang if n==0 so test first. */
int numZeros = 0;
int n = pink->pink_Index;
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.
*/
pink->pink_RunningSum -= pink->pink_Rows[numZeros];
newRandom = ((long)GenerateRandomNumber()) >> PINK_RANDOM_SHIFT;
pink->pink_RunningSum += newRandom;
pink->pink_Rows[numZeros] = newRandom;
}
/* Add extra white noise value. */
newRandom = ((long)GenerateRandomNumber()) >> PINK_RANDOM_SHIFT;
sum = pink->pink_RunningSum + newRandom;
/* Scale to range of -1.0 to 0.9999. */
output = pink->pink_Scalar * sum;
#ifdef PINK_MEASURE
/* Check Min/Max */
if( output > pinkMax ) pinkMax = output;
else if( output < pinkMin ) pinkMin = output;
#endif
return output;
}
/*******************************************************************/
#define PINK_TEST
#ifdef PINK_TEST
/* Context for callback routine. */
typedef struct
{
PinkNoise leftPink;
PinkNoise rightPink;
unsigned int sampsToGo;
}
paTestData;
/* This routine will be called by the PortAudio engine when audio is needed.
** It may called at interrupt level on some machines so don't do anything
** that could mess up the system like calling malloc() or free().
*/
static int patestCallback( void *inputBuffer, void *outputBuffer,
unsigned long framesPerBuffer,
PaTimestamp outTime, void *userData )
{
int finished;
int i;
int numFrames;
paTestData *data = (paTestData*)userData;
float *out = (float*)outputBuffer;
(void) inputBuffer; /* Prevent "unused variable" warnings. */
(void) outTime;
/* Are we almost at end. */
if( data->sampsToGo < framesPerBuffer )
{
numFrames = data->sampsToGo;
finished = 1;
}
else
{
numFrames = framesPerBuffer;
finished = 0;
}
for( i=0; i<numFrames; i++ )
{
*out++ = GeneratePinkNoise( &data->leftPink );
*out++ = GeneratePinkNoise( &data->rightPink );
}
data->sampsToGo -= numFrames;
return finished;
}
/*******************************************************************/
int main(void);
int main(void)
{
PortAudioStream *stream;
PaError err;
paTestData data;
int totalSamps;
/* Initialize two pink noise signals with different numbers of rows. */
InitializePinkNoise( &data.leftPink, 12 );
InitializePinkNoise( &data.rightPink, 16 );
/* Look at a few values. */
{
int i;
float pink;
for( i=0; i<20; i++ )
{
pink = GeneratePinkNoise( &data.leftPink );
printf("Pink = %f\n", pink );
}
}
data.sampsToGo = totalSamps = 8*44100; /* Play for a few seconds. */
err = Pa_Initialize();
if( err != paNoError ) goto error;
/* Open a stereo PortAudio stream so we can hear the result. */
err = Pa_OpenStream(
&stream,
paNoDevice,
0, /* no input */
paFloat32, /* 32 bit floating point input */
NULL,
Pa_GetDefaultOutputDeviceID(), /* default output device */
2, /* stereo output */
paFloat32, /* 32 bit floating point output */
NULL,
44100.,
2048, /* 46 msec buffers */
0, /* number of buffers, if zero then use default minimum */
paClipOff, /* we won't output out of range samples so don't bother clipping them */
patestCallback,
&data );
if( err != paNoError ) goto error;
err = Pa_StartStream( stream );
if( err != paNoError ) goto error;
printf("Waiting for sound to finish.\n");
while( Pa_StreamActive( stream ) )
{
Pa_Sleep(100); /* SPIN! */
}
err = Pa_CloseStream( stream );
if( err != paNoError ) goto error;
#ifdef PINK_MEASURE
printf("Pink min = %f, max = %f\n", pinkMin, pinkMax );
#endif
Pa_Terminate();
return 0;
error:
Pa_Terminate();
fprintf( stderr, "An error occured while using the portaudio stream\n" );
fprintf( stderr, "Error number: %d\n", err );
fprintf( stderr, "Error message: %s\n", Pa_GetErrorText( err ) );
return 0;
}
#endif /* PINK_TEST */
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