/** @file patest_out_underflow.c	@ingroup test_src	@brief Count output underflows (using paOutputUnderflow flag) 	under overloaded and normal conditions.	@author Ross Bencina <rossb@audiomulch.com>	@author Phil Burk <philburk@softsynth.com>*//* * $Id: patest_out_underflow.c 1097 2006-08-26 08:27:53Z rossb $ * * This program uses the PortAudio Portable Audio Library. * For more information see: http://www.portaudio.com * Copyright (c) 1999-2004 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. * * 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. *//* * The text above constitutes the entire PortAudio license; however,  * the PortAudio community also makes the following non-binding requests: * * 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. It is also  * requested that these non-binding requests be included along with the  * license above. */#include <stdio.h>#include <math.h>#include "portaudio.h"#define MAX_SINES     (500)#define MAX_LOAD      (1.2)#define SAMPLE_RATE   (44100)#define FRAMES_PER_BUFFER  (512)#ifndef M_PI#define M_PI  (3.14159265)#endif#define TWOPI (M_PI * 2.0)typedef struct paTestData{    int sineCount;    double phases[MAX_SINES];    int countUnderflows;    int outputUnderflowCount;}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( const void *inputBuffer, void *outputBuffer,                           unsigned long framesPerBuffer,                           const PaStreamCallbackTimeInfo* timeInfo,                           PaStreamCallbackFlags statusFlags,                           void *userData ){    paTestData *data = (paTestData*)userData;    float *out = (float*)outputBuffer;    unsigned long i;    int j;    int finished = paContinue;    (void) timeInfo;    /* Prevent unused variable warning. */    (void) inputBuffer; /* Prevent unused variable warning. */    if( data->countUnderflows && (statusFlags & paOutputUnderflow) )        data->outputUnderflowCount++;    for( i=0; i<framesPerBuffer; i++ )    {        float output = 0.0;        double phaseInc = 0.02;        double phase;        for( j=0; j<data->sineCount; j++ )        {            /* Advance phase of next oscillator. */            phase = data->phases[j];            phase += phaseInc;            if( phase > TWOPI ) phase -= TWOPI;            phaseInc *= 1.02;            if( phaseInc > 0.5 ) phaseInc *= 0.5;            /* This is not a very efficient way to calc sines. */            output += (float) sin( phase );            data->phases[j] = phase;        }        *out++ = (float) (output / data->sineCount);    }    return finished;}/*******************************************************************/int main(void);int main(void){    PaStreamParameters outputParameters;    PaStream *stream;    PaError err;    int safeSineCount, stressedSineCount;    int safeUnderflowCount, stressedUnderflowCount;    paTestData data = {0};    double load;    printf("PortAudio Test: output sine waves, count underflows. SR = %d, BufSize = %d. MAX_LOAD = %f\n",        SAMPLE_RATE, FRAMES_PER_BUFFER, (float)MAX_LOAD );    err = Pa_Initialize();    if( err != paNoError ) goto error;        outputParameters.device = Pa_GetDefaultOutputDevice();  /* default output device */    outputParameters.channelCount = 1;                      /* mono output */    outputParameters.sampleFormat = paFloat32;              /* 32 bit floating point output */    outputParameters.suggestedLatency = Pa_GetDeviceInfo( outputParameters.device )->defaultLowOutputLatency;    outputParameters.hostApiSpecificStreamInfo = NULL;    err = Pa_OpenStream(              &stream,              NULL,         /* no input */              &outputParameters,              SAMPLE_RATE,              FRAMES_PER_BUFFER,              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("Establishing load conditions...\n" );    /* Determine number of sines required to get to 50% */    do    {        data.sineCount++;        Pa_Sleep( 100 );        load = Pa_GetStreamCpuLoad( stream );        printf("sineCount = %d, CPU load = %f\n", data.sineCount, load );    }    while( load < 0.5 && data.sineCount < (MAX_SINES-1));    safeSineCount = data.sineCount;    /* Calculate target stress value then ramp up to that level*/    stressedSineCount = (int) (2.0 * data.sineCount * MAX_LOAD );    if( stressedSineCount > MAX_SINES )        stressedSineCount = MAX_SINES;    for( ; data.sineCount < stressedSineCount; data.sineCount++ )    {        Pa_Sleep( 100 );        load = Pa_GetStreamCpuLoad( stream );        printf("STRESSING: sineCount = %d, CPU load = %f\n", data.sineCount, load );    }        printf("Counting underflows for 5 seconds.\n");    data.countUnderflows = 1;    Pa_Sleep( 5000 );    stressedUnderflowCount = data.outputUnderflowCount;    data.countUnderflows = 0;    data.sineCount = safeSineCount;    printf("Resuming safe load...\n");    Pa_Sleep( 1500 );    data.outputUnderflowCount = 0;    Pa_Sleep( 1500 );    load = Pa_GetStreamCpuLoad( stream );    printf("sineCount = %d, CPU load = %f\n", data.sineCount, load );    printf("Counting underflows for 5 seconds.\n");    data.countUnderflows = 1;    Pa_Sleep( 5000 );    safeUnderflowCount = data.outputUnderflowCount;        printf("Stop stream.\n");    err = Pa_StopStream( stream );    if( err != paNoError ) goto error;        err = Pa_CloseStream( stream );    if( err != paNoError ) goto error;        Pa_Terminate();    if( stressedUnderflowCount == 0 )        printf("Test failed, no output underflows detected under stress.\n");    else if( safeUnderflowCount != 0 )        printf("Test failed, %d unexpected underflows detected under safe load.\n", safeUnderflowCount);    else        printf("Test passed, %d expected output underflows detected under stress, 0 unexpected underflows detected under safe load.\n", stressedUnderflowCount );    return err;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 err;}