/** @file patest_underflow.c	@ingroup test_src	@brief Simulate an output buffer underflow condition.	Tests whether the stream can be stopped when underflowing buffers.	@author Ross Bencina <rossb@audiomulch.com>	@author Phil Burk <philburk@softsynth.com>*//* * $Id: patest_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) 1999-2000 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. * * 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 NUM_SECONDS   (20)#define SAMPLE_RATE   (44100)#define FRAMES_PER_BUFFER  (2048)#define MSEC_PER_BUFFER  ( (FRAMES_PER_BUFFER * 1000) / SAMPLE_RATE )#ifndef M_PI#define M_PI  (3.14159265)#endif#define TABLE_SIZE   (200)typedef struct{    float sine[TABLE_SIZE];    int left_phase;    int right_phase;    int sleepTime;}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 finished = 0;    (void) inputBuffer; /* Prevent unused variable warnings. */    for( i=0; i<framesPerBuffer; i++ )    {        *out++ = data->sine[data->left_phase];  /* left */        *out++ = data->sine[data->right_phase];  /* right */        data->left_phase += 1;        if( data->left_phase >= TABLE_SIZE ) data->left_phase -= TABLE_SIZE;        data->right_phase += 3; /* higher pitch so we can distinguish left and right. */        if( data->right_phase >= TABLE_SIZE ) data->right_phase -= TABLE_SIZE;    }    /* Cause underflow to occur. */    if( data->sleepTime > 0 ) Pa_Sleep( data->sleepTime );    data->sleepTime += 1;    return finished;}/*******************************************************************/int main(void);int main(void){    PaStreamParameters outputParameters;    PaStream *stream;    PaError err;    paTestData data;    int i;    printf("PortAudio Test: output sine wave. SR = %d, BufSize = %d\n", SAMPLE_RATE, FRAMES_PER_BUFFER);    /* initialise sinusoidal wavetable */    for( i=0; i<TABLE_SIZE; i++ )    {        data.sine[i] = (float) sin( ((double)i/(double)TABLE_SIZE) * M_PI * 2. );    }    data.left_phase = data.right_phase = data.sleepTime = 0;    err = Pa_Initialize();    if( err != paNoError ) goto error;        outputParameters.device = Pa_GetDefaultOutputDevice(); /* default output device */    outputParameters.channelCount = 2;       /* stereo 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;    while( data.sleepTime < (2 * MSEC_PER_BUFFER) )    {        printf("SleepTime = %d\n", data.sleepTime );        Pa_Sleep( data.sleepTime );    }    printf("Try to stop stream.\n");    err = Pa_StopStream( stream );    if( err != paNoError ) goto error;    err = Pa_CloseStream( stream );    if( err != paNoError ) goto error;    Pa_Terminate();    printf("Test finished.\n");    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;}