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///////////////////////////////////////////////////////////////////////////////////
// A small demo of sonar.
// Program allow distance measuring.
// Uses cross-correlation algorithm to find echos
//
// Author: kaklik (kaklik@mlab.cz)
//
///////////////////////////////////////////////////////////////////////////////////
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sched.h>
#include <errno.h>
#include <getopt.h>
#include <alsa/asoundlib.h>
#include <sys/time.h>
#include <math.h>
static char *device = "plughw:0,0"; /* playback device */
static snd_pcm_format_t format = SND_PCM_FORMAT_S16; /* sample format */
static unsigned int rate = 98000; /* stream rate */
static unsigned int buffer_time = 500000; /* ring buffer length in us */
static unsigned int period_time = 100000; /* period time in us */
static int verbose = 0; /* verbose flag */
static int resample = 1; /* enable alsa-lib resampling */
static int period_event = 0; /* produce poll event after each period */
#define SOUND_SPEED 340
#define SIGNAL_SAMPLES 100000
#define CHIRP_OFFSET 0
unsigned int chirp_size;
int period=0;
int cperiod=0;
int chirp[100000];
short signal[1000000]; // record 6s of input samples
static snd_pcm_sframes_t buffer_size; // size of buffer at sound card
static snd_pcm_sframes_t period_size; //samples per frame
static snd_output_t *output = NULL;
static int set_hwparams ( snd_pcm_t *handle, snd_pcm_hw_params_t *params, unsigned int channels )
{
unsigned int rrate;
snd_pcm_uframes_t size;
int err, dir;
/* choose all parameters */
err = snd_pcm_hw_params_any ( handle, params );
if ( err < 0 )
{
printf ( "Broken configuration for playback: no configurations available: %s\n", snd_strerror ( err ) );
return err;
}
/* set hardware resampling */
err = snd_pcm_hw_params_set_rate_resample ( handle, params, resample );
if ( err < 0 )
{
printf ( "Resampling setup failed for playback: %s\n", snd_strerror ( err ) );
return err;
}
/* set the interleaved read/write format */
err = snd_pcm_hw_params_set_access ( handle, params, SND_PCM_ACCESS_RW_INTERLEAVED );
if ( err < 0 )
{
printf ( "Access type not available for playback: %s\n", snd_strerror ( err ) );
return err;
}
/* set the sample format */
err = snd_pcm_hw_params_set_format ( handle, params, format );
if ( err < 0 )
{
printf ( "Sample format not available for playback: %s\n", snd_strerror ( err ) );
return err;
}
/* set the count of channels */
err = snd_pcm_hw_params_set_channels ( handle, params, channels );
if ( err < 0 )
{
printf ( "Channels count (%i) not available for playbacks: %s\n", channels, snd_strerror ( err ) );
return err;
}
/* set the stream rate */
rrate = rate;
err = snd_pcm_hw_params_set_rate_near ( handle, params, &rrate, 0 );
if ( err < 0 )
{
printf ( "Rate %iHz not available for playback: %s\n", rate, snd_strerror ( err ) );
return err;
}
if ( rrate != rate )
{
printf ( "Rate doesn't match (requested %iHz, get %iHz)\n", rate, err );
return -EINVAL;
}
else printf ( "Rate set to %i Hz\n", rate, err );
/* set the buffer time */
err = snd_pcm_hw_params_set_buffer_time_near ( handle, params, &buffer_time, &dir );
if ( err < 0 )
{
printf ( "Unable to set buffer time %i for playback: %s\n", buffer_time, snd_strerror ( err ) );
return err;
}
err = snd_pcm_hw_params_get_buffer_size ( params, &size );
if ( err < 0 )
{
printf ( "Unable to get buffer size for playback: %s\n", snd_strerror ( err ) );
return err;
}
buffer_size = size;
/* set the period time */
err = snd_pcm_hw_params_set_period_time_near ( handle, params, &period_time, &dir );
if ( err < 0 )
{
printf ( "Unable to set period time %i for playback: %s\n", period_time, snd_strerror ( err ) );
return err;
}
err = snd_pcm_hw_params_get_period_size ( params, &size, &dir );
if ( err < 0 )
{
printf ( "Unable to get period size for playback: %s\n", snd_strerror ( err ) );
return err;
}
period_size = size;
/* write the parameters to device */
err = snd_pcm_hw_params ( handle, params );
if ( err < 0 )
{
printf ( "Unable to set hw params for playback: %s\n", snd_strerror ( err ) );
return err;
}
return 0;
}
static int set_swparams ( snd_pcm_t *handle, snd_pcm_sw_params_t *swparams )
{
int err;
/* get the current swparams */
err = snd_pcm_sw_params_current ( handle, swparams );
if ( err < 0 )
{
printf ( "Unable to determine current swparams for playback: %s\n", snd_strerror ( err ) );
return err;
}
/* start the transfer when the buffer is almost full: */
/* (buffer_size / avail_min) * avail_min */
err = snd_pcm_sw_params_set_start_threshold ( handle, swparams, ( buffer_size / period_size ) * period_size );
if ( err < 0 )
{
printf ( "Unable to set start threshold mode for playback: %s\n", snd_strerror ( err ) );
return err;
}
/* allow the transfer when at least period_size samples can be processed */
/* or disable this mechanism when period event is enabled (aka interrupt like style processing) */
err = snd_pcm_sw_params_set_avail_min ( handle, swparams, period_event ? buffer_size : period_size );
if ( err < 0 )
{
printf ( "Unable to set avail min for playback: %s\n", snd_strerror ( err ) );
return err;
}
/* enable period events when requested */
if ( period_event )
{
err = snd_pcm_sw_params_set_period_event ( handle, swparams, 1 );
if ( err < 0 )
{
printf ( "Unable to set period event: %s\n", snd_strerror ( err ) );
return err;
}
}
/* write the parameters to the playback device */
err = snd_pcm_sw_params ( handle, swparams );
if ( err < 0 )
{
printf ( "Unable to set sw params for playback: %s\n", snd_strerror ( err ) );
return err;
}
return 0;
}
struct async_private_data
{
signed short *samples;
snd_pcm_channel_area_t *areas;
unsigned int period;
};
////// SIGNAL GENERATION STUFF
/*int linear_chirp(int *pole, int delka_pole){ // vygeneruje linearni chirp a vzorky ulozi do pole
static const float f0 = 0.0001;
static const float k = 0.00001;
int t;
// if((spozdeni+delka) < delka_pole)
for(t=0;t < delka_pole;t++) pole[t] = round ( 10000*sin(2*M_PI*(t+faze)*(f0+(k/2)*(t+faze))) );
faze +=t;
// else return 0;
}*/
// vygeneruje linearni chirp a vzorky ulozi do pole
unsigned int linear_windowed_chirp ( unsigned int *pole, unsigned int delka_pole,unsigned int offset )
{
unsigned int maxval = ( 1 << ( snd_pcm_format_width ( format ) - 1 ) ) - 1;
static const float f0 = 1000;
static const float fmax = 7000;
static const float Tw = 0.002;
static float k;
unsigned int n=0;
double t;
unsigned int perioda;
k=2* ( fmax-f0 ) /Tw;
perioda = rate*Tw;
for ( n=0;n<=perioda;n++ )
{
t = ( double ) n/ ( double ) rate;
pole[n+offset] = ( short ) floor ( ( 0.35875 - 0.48829*cos ( 2*M_PI*t*1/Tw ) + 0.14128*cos ( 2*M_PI*2*t*1/Tw ) - 0.01168*cos ( 2*M_PI*3*t*1/Tw ) ) *maxval*sin ( 2*M_PI* ( t ) * ( f0+ ( k/2 ) * ( t ) ) ) );
}
return ( perioda+offset );
}
// generate sine samples and store
int sine ( unsigned int *pole, unsigned int delka_pole )
{
unsigned int maxval = ( 1 << ( snd_pcm_format_width ( format ) - 1 ) ) - 1;
unsigned int n;
double t;
for ( n=0;n < delka_pole;n++ )
{
t = 440.0 * ( double ) n/ ( double ) rate;
pole[n] = ( short ) floor ( maxval*sin ( 2*M_PI*t ) );
}
}
//// generate simple sine ping
unsigned int sine_ping ( unsigned int *pole, unsigned int delka_pole,unsigned int offset, double frequency )
{
unsigned int maxval = ( 1 << ( snd_pcm_format_width ( format ) - 1 ) ) - 1;
unsigned int n;
double t;
for ( n=0;n < delka_pole;n++ )
{
t = frequency * ( double ) n/ ( double ) rate;
pole[n] = ( short ) floor ( maxval*sin ( 2*M_PI*t ) );
}
}
/////////// CALL BACK STUFF ///////////////////
static void async_playback_callback ( snd_async_handler_t *ahandler )
{
snd_pcm_t *handle = snd_async_handler_get_pcm ( ahandler );
/* struct async_private_data *data = snd_async_handler_get_callback_private(ahandler);
signed short *samples = data->samples;
snd_pcm_channel_area_t *areas = data->areas;*/
snd_pcm_sframes_t avail;
int err;
avail = snd_pcm_avail_update ( handle );
while ( ( avail >= period_size ) && ( ( period*period_size ) < chirp_size ) )
{
err = snd_pcm_writei ( handle, ( chirp+period*period_size ), period_size );
if ( err < 0 )
{
printf ( "Write error: %s\n", snd_strerror ( err ) );
exit ( EXIT_FAILURE );
}
if ( err != period_size )
{
printf ( "Write error: written %i expected %li\n", err, period_size );
exit ( EXIT_FAILURE );
}
avail = snd_pcm_avail_update ( handle );
period++;
}
}
static void async_capture_callback ( snd_async_handler_t *ahandler )
{
snd_pcm_t *handle = snd_async_handler_get_pcm ( ahandler );
/* struct async_private_data *data = snd_async_handler_get_callback_private(ahandler);
signed short *samples = data->samples;
snd_pcm_channel_area_t *areas = data->areas;*/
snd_pcm_sframes_t avail;
int err;
avail = snd_pcm_avail_update ( handle );
while ( ( avail >= period_size ) /*&& ((period*period_size) < (CHIRP_SIZE-100))*/ ) // segmentation fault checking disabled
{
err = snd_pcm_readi ( handle, ( signal+cperiod*period_size ), period_size );
if ( err < 0 )
{
printf ( "Read error: %s\n", snd_strerror ( err ) );
exit ( EXIT_FAILURE );
}
if ( err != period_size )
{
printf ( "Read error: red %i expected %li\n", err, period_size );
exit ( EXIT_FAILURE );
}
avail = snd_pcm_avail_update ( handle );
cperiod++;
}
}
int main ( int argc, char *argv[] )
{
snd_pcm_t *playback_handle, *capture_handle;
int err;
snd_pcm_hw_params_t *hwparams;
snd_pcm_sw_params_t *swparams;
signed short *frame; // pointer to array of samples
unsigned int chn;
snd_pcm_channel_area_t *areas;
struct async_private_data data;
snd_async_handler_t *chandler, *phandler;
int count;
unsigned int i,j,m,n;
unsigned int delay[10]; //store delay of signifed correlation
long int l,r; // store correlation at strict time
long int correlationl[SIGNAL_SAMPLES]; //array to store correlation curve
long int correlationr[SIGNAL_SAMPLES]; //array to store correlation curve
int L_signal[SIGNAL_SAMPLES];
int R_signal[SIGNAL_SAMPLES];
FILE *out;
snd_pcm_hw_params_alloca ( &hwparams );
snd_pcm_sw_params_alloca ( &swparams );
printf ( "Simple PC sonar ver. 000000001 starting work.. \n" );
//open and set playback device
if ( ( err = snd_pcm_open ( &playback_handle, device, SND_PCM_STREAM_PLAYBACK, 0 ) ) < 0 )
{
printf ( "Playback open error: %s\n", snd_strerror ( err ) );
return 0;
}
if ( ( err = set_hwparams ( playback_handle, hwparams, 1 ) ) < 0 )
{
printf ( "Setting of hwparams failed: %s\n", snd_strerror ( err ) );
exit ( EXIT_FAILURE );
}
if ( ( err = set_swparams ( playback_handle, swparams ) ) < 0 )
{
printf ( "Setting of swparams failed: %s\n", snd_strerror ( err ) );
exit ( EXIT_FAILURE );
}
//open and set capture device
if ( ( err = snd_pcm_open ( &capture_handle, device, SND_PCM_STREAM_CAPTURE, 0 ) ) < 0 )
{
printf ( "Playback open error: %s\n", snd_strerror ( err ) );
return 0;
}
if ( ( err = set_hwparams ( capture_handle, hwparams, 2 ) ) < 0 )
{
printf ( "Setting of hwparams failed: %s\n", snd_strerror ( err ) );
exit ( EXIT_FAILURE );
}
if ( ( err = set_swparams ( capture_handle, swparams ) ) < 0 )
{
printf ( "Setting of swparams failed: %s\n", snd_strerror ( err ) );
exit ( EXIT_FAILURE );
}
/// generate ping pattern
chirp_size=linear_windowed_chirp ( chirp,1000000, CHIRP_OFFSET );
/// register playback callback
err = snd_async_add_pcm_handler ( &phandler, playback_handle, async_playback_callback, &data ); // fill by dummy &data
if ( err < 0 )
{
printf ( "Unable to register async handler\n" );
exit ( EXIT_FAILURE );
}
for ( period = 0; period < 2; period++ )
{
err = snd_pcm_writei ( playback_handle, ( chirp+period*period_size ), period_size );
if ( err < 0 )
{
printf ( "Initial write error: %s\n", snd_strerror ( err ) );
exit ( EXIT_FAILURE );
}
if ( err != period_size )
{
printf ( "Initial write error: written %i expected %li\n", err, period_size );
exit ( EXIT_FAILURE );
}
}
// register capture callback
err = snd_async_add_pcm_handler ( &chandler, capture_handle, async_capture_callback, &data ); // fill by dummy &data
if ( err < 0 )
{
printf ( "Unable to register async handler\n" );
exit ( EXIT_FAILURE );
}
snd_pcm_link ( capture_handle,playback_handle ); //link capture and playback together
//start sream
if ( ( err = snd_pcm_prepare ( capture_handle ) ) < 0 )
{
fprintf ( stderr, "cannot prepare audio interface for use (%s)\n",
snd_strerror ( err ) );
exit ( 1 );
}
err = snd_pcm_start ( capture_handle );
if ( err < 0 )
{
printf ( "Start error: %s\n", snd_strerror ( err ) );
exit ( EXIT_FAILURE );
}
//wait until all samples aren't transmitted
printf ( "Waiting for transmitt all samples\n" );
while ( cperiod<10 )
{
sleep ( 1 );
printf ( "." );
}
//// stop audio??
j=0;
for ( i=0;i < SIGNAL_SAMPLES;i++ )
{
L_signal[i]=signal[j];
R_signal[i]=signal[j+1];
j+=2;
}
// linear_windowed_chirp(L_signal,1000000, 1000);
printf ( "\nData transmitted... \ncorrelating...\n" );
for ( n=0; n < ( SIGNAL_SAMPLES - chirp_size );n++ )
{
l=0;
r=0;
for ( m=CHIRP_OFFSET;m < chirp_size;m++ )
{
l += chirp[m]*L_signal[m+n]; // correlate with left channel
r += chirp[m]*R_signal[m+n]; // correlate with right channel
}
correlationl[n]=l;
correlationr[n]=r;
}
printf ( "\nSearching echos...\n" );
r=0;
l=0;
for ( n=0; n < ( SIGNAL_SAMPLES - chirp_size );n++ ) //najde nejvetsi korelace
{
if ( l < correlationl[n] )
{
delay[1] = n;
l = correlationl[n];
}
if ( r < correlationr[n] )
{
delay[2] = n;
r = correlationr[n];
}
}
out=fopen ( "./output.txt","w" );
j=0;
for ( i=0;i<=100000;i++ )
{
fprintf ( out,"%6d %6d %6d %6d %9ld %9ld\n",i,chirp[i],L_signal[i],R_signal[i],correlationl[i], correlationr[i] );
j+=2;
}
fclose ( out );
printf ( "\nEcho zacina na: %d vzorku.\n", delay[1] );
printf ( "Casove na: %f s\n", ( ( float ) delay[1]/rate ) );
printf ( "vzdalenost: %f m\n", ( SOUND_SPEED* ( float ) delay[1]/rate ) );
snd_pcm_close ( playback_handle );
snd_pcm_close ( capture_handle );
return 0;
}