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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>#define SOUND_SPEED 340.0 // sound speed in air in metrs per second#define MAX_RANGE 10.0 // maximal working radius in metersstatic char *device = "plughw:0,0"; /* playback device */static snd_pcm_format_t format = SND_PCM_FORMAT_S16; /* sample format */static unsigned int rate = 96000; /* stream rate */static unsigned int buffer_time = MAX_RANGE / SOUND_SPEED * 1e6; /* ring buffer length in us */static unsigned int period_time = MAX_RANGE / SOUND_SPEED * 1e5; /* period time in us */static int resample = 1; /* enable alsa-lib resampling */#define SIGNAL_SAMPLES 100000unsigned int chirp_size;int period=0;int cperiod=0;short *chirp;short signal[1000000]; // record 6s of input samplesstatic snd_pcm_sframes_t buffer_size; // size of buffer at sound cardstatic snd_pcm_sframes_t period_size; //samples per framestatic 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;printf("Bufffer size set to: %d Requested buffer time: %ld \n", (int) buffer_size, (long) buffer_time);/// set the period timeerr = 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;printf("Period size set to: %d Requested period time: %ld \n", (int) period_size, (long) period_time);/* 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: never fou our caseerr = snd_pcm_sw_params_set_start_threshold(handle, swparams, 2 * buffer_size);if (err < 0){printf("Unable to set start threshold mode for playback: %s\n", snd_strerror(err));return err;}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 STUFFunsigned int linear_windowed_chirp(short *pole){unsigned int maxval = (1 << (snd_pcm_format_width(format) - 1)) - 1;static const float f0 = 1000; //starting frequencystatic const float fmax = 7000; //ending frequencystatic const float Tw = 0.002;static float k;unsigned int n=0;double t;unsigned int chirp_samples; // number of samples per periodk=2*(fmax-f0)/Tw;chirp_samples = ceil(rate*Tw);for (n=0;n<=chirp_samples;n++){t = (double) n / (double)rate;pole[n] = (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 (chirp_samples);}/////////// CALL BACK STUFF ///////////////////static void async_playback_callback(snd_async_handler_t *ahandler){snd_pcm_t *handle = snd_async_handler_get_pcm(ahandler);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);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 samplesunsigned 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 correlationlong int l,r; // store correlation at strict timelong int correlationl[SIGNAL_SAMPLES]; //array to store correlation curvelong int correlationr[SIGNAL_SAMPLES]; //array to store correlation curveint 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 deviceif ((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 deviceif ((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 patternchirp = malloc(2*period_size * sizeof(short));chirp_size = linear_windowed_chirp(chirp);// register playback callback/* err = snd_async_add_pcm_handler(&phandler, playback_handle, async_playback_callback, &data); // fill by dummy &dataif (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_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 &dataif (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);}else printf("Capture device prepared...\n");*/err = snd_pcm_start(playback_handle);if (err < 0){printf("Start error: %s\n", snd_strerror(err));exit(EXIT_FAILURE);}else printf("Waiting for transmitt all samples\n");while ( snd_pcm_avail(capture_handle) < period_size ){usleep(1000);printf(".");}err = snd_pcm_drop(capture_handle);if (err < 0){printf("Stop error: %s\n", snd_strerror(err));exit(EXIT_FAILURE);}j=0;for (i=0;i < SIGNAL_SAMPLES;i++){L_signal[i]=signal[j];R_signal[i]=signal[j+1];j+=2;}printf("Data transmitted... \ncorrelating...\n");for (n=0; n < (SIGNAL_SAMPLES - chirp_size);n++){l=0;r=0;for (m=0;m < chirp_size;m++){l += chirp[m]*L_signal[m+n]; // correlate with left channelr += chirp[m]*R_signal[m+n]; // correlate with right channel}correlationl[n]=l;correlationr[n]=r;}printf("Searching 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];}}printf("\nWriting output file...\n");out=fopen("/tmp/sonar.txt","w");j=0;for (i=0;i<=period_size;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;}