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Use Interpolating sine lookup to eliminate differences in math lib performance

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between hosts.
This commit is contained in:
philburk 2002-03-28 18:15:43 +00:00
commit e66425d00c
1 changed files with 47 additions and 9 deletions
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56
pa_tests/patest_maxsines.c
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@ -40,20 +40,44 @@
#include "portaudio.h"
#define MAX_SINES (500)
#define MAX_USAGE (0.8)
#define SAMPLE_RATE (44100)
#define FREQ_TO_PHASE_INC(freq) (freq/(float)SAMPLE_RATE)
#define MIN_PHASE_INC FREQ_TO_PHASE_INC(200.0f)
#define MAX_PHASE_INC (MIN_PHASE_INC * (1 << 5))
#define FRAMES_PER_BUFFER (512)
#ifndef M_PI
#define M_PI (3.14159265)
#endif
#define TWOPI (M_PI * 2.0)
#define TABLE_SIZE (512)
typedef struct paTestData
{
int numSines;
float sine[TABLE_SIZE + 1]; /* add one for guard point for interpolation */
double phases[MAX_SINES];
}
paTestData;
/* Convert phase between and 1.0 to sine value
* using linear interpolation.
*/
float LookupSine( paTestData *data, float phase );
float LookupSine( paTestData *data, float phase )
{
float fIndex = phase*TABLE_SIZE;
int index = (int) fIndex;
float fract = fIndex - index;
float lo = data->sine[index];
float hi = data->sine[index+1];
float val = lo + fract*(hi-lo);
return val;
}
/* 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().
@ -65,33 +89,39 @@ static int patestCallback( void *inputBuffer, void *outputBuffer,
paTestData *data = (paTestData*)userData;
float *out = (float*)outputBuffer;
float outSample;
float scaler;
int numForScale;
unsigned long i;
int j;
int finished = 0;
(void) outTime; /* Prevent unused variable warnings. */
(void) inputBuffer;
/* Detemine amplitude scaling factor */
numForScale = data->numSines;
if( numForScale < 8 ) numForScale = 8; /* prevent pops at beginning */
scaler = 1.0f / numForScale;
for( i=0; i<framesPerBuffer; i++ )
{
float output = 0.0;
double phaseInc = 0.02;
double phaseInc = MIN_PHASE_INC;
double phase;
for( j=0; j<data->numSines; j++ )
{
/* Advance phase of next oscillator. */
phase = data->phases[j];
phase += phaseInc;
if( phase > TWOPI ) phase -= TWOPI;
if( phase >= 1.0 ) phase -= 1.0;
phaseInc *= 1.02;
if( phaseInc > 0.5 ) phaseInc *= 0.5;
/* This is not a very efficient way to calc sines. */
output += (float) sin( phase );
output += LookupSine(data, phase);
data->phases[j] = phase;
phaseInc *= 1.02;
if( phaseInc > MAX_PHASE_INC ) phaseInc = MIN_PHASE_INC;
}
outSample = (float) (output / data->numSines);
outSample = (float) (output * scaler);
*out++ = outSample; /* Left */
*out++ = outSample; /* Right */
}
@ -102,12 +132,19 @@ static int patestCallback( void *inputBuffer, void *outputBuffer,
int main(void);
int main(void)
{
int i;
PortAudioStream *stream;
PaError err;
paTestData data = {0};
double load;
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.sine[TABLE_SIZE] = data.sine[0]; /* set guard point */
err = Pa_Initialize();
if( err != paNoError ) goto error;
@ -131,6 +168,7 @@ int main(void)
err = Pa_StartStream( stream );
if( err != paNoError ) goto error;
/* Play an increasing number of sine waves until we hit MAX_USAGE */
do
{
data.numSines++;
@ -140,7 +178,7 @@ int main(void)
printf("numSines = %d, CPU load = %f\n", data.numSines, load );
fflush( stdout );
}
while( (load < 0.8) && (data.numSines < MAX_SINES) );
while( (load < MAX_USAGE) && (data.numSines < MAX_SINES) );
err = Pa_StopStream( stream );
if( err != paNoError ) goto error;