comparison src/portaudio_20140130/examples/paex_saw.c @ 124:e3d5853d5918

Current stable PortAudio source

+/** @file paex_saw.c
+	@ingroup examples_src
+	@brief Play a simple (aliasing) sawtooth wave.
+	@author Phil Burk  http://www.softsynth.com
+*/
+/*
+ * $Id: paex_saw.c 1752 2011-09-08 03:21:55Z philburk $
+ *
+ * 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   (4)
+#define SAMPLE_RATE   (44100)
+
+typedef struct
+{
+    float left_phase;
+    float right_phase;
+}
+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 )
+{
+    /* Cast data passed through stream to our structure. */
+    paTestData *data = (paTestData*)userData;
+    float *out = (float*)outputBuffer;
+    unsigned int i;
+    (void) inputBuffer; /* Prevent unused variable warning. */
+
+    for( i=0; i<framesPerBuffer; i++ )
+    {
+        *out++ = data->left_phase;  /* left */
+        *out++ = data->right_phase;  /* right */
+        /* Generate simple sawtooth phaser that ranges between -1.0 and 1.0. */
+        data->left_phase += 0.01f;
+        /* When signal reaches top, drop back down. */
+        if( data->left_phase >= 1.0f ) data->left_phase -= 2.0f;
+        /* higher pitch so we can distinguish left and right. */
+        data->right_phase += 0.03f;
+        if( data->right_phase >= 1.0f ) data->right_phase -= 2.0f;
+    }
+    return 0;
+}
+
+/*******************************************************************/
+static paTestData data;
+int main(void);
+int main(void)
+{
+    PaStream *stream;
+    PaError err;
+    
+    printf("PortAudio Test: output sawtooth wave.\n");
+    /* Initialize our data for use by callback. */
+    data.left_phase = data.right_phase = 0.0;
+    /* Initialize library before making any other calls. */
+    err = Pa_Initialize();
+    if( err != paNoError ) goto error;
+    
+    /* Open an audio I/O stream. */
+    err = Pa_OpenDefaultStream( &stream,
+                                0,          /* no input channels */
+                                2,          /* stereo output */
+                                paFloat32,  /* 32 bit floating point output */
+                                SAMPLE_RATE,
+                                256,        /* frames per buffer */
+                                patestCallback,
+                                &data );
+    if( err != paNoError ) goto error;
+
+    err = Pa_StartStream( stream );
+    if( err != paNoError ) goto error;
+
+    /* Sleep for several seconds. */
+    Pa_Sleep(NUM_SECONDS*1000);
+
+    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;
+}