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///////////////////////////////////////////////////////////////////////////////////// This small demo of sonar.// Program allow distance measuring.///////////////////////////////////////////////////////////////////////////////////////#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 channels = 1; /* count of channels */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 100000unsigned int chirp_size;int period=0;int cperiod=0;int chirp[100000];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,snd_pcm_access_t access){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, access);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;};/*int linear_chirp(int *pole, int delka_pole){ // vygeneruje linearni chirp a vzorky ulozi do polestatic 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 poleunsigned int linear_windowed_chirp(unsigned int *pole, unsigned int delka_pole){unsigned int maxval = (1 << (snd_pcm_format_width(format) - 1)) - 1;static const float f0 = 3000;static const float fmax = 5000;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] = (short) round ( (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;}// generate sine samples and storeint 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) round(maxval*sin(2*M_PI*t));}}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 disablederr = 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 correlationdouble r;double correlation[1000000]; //array to store correlation curveFILE *out;snd_pcm_hw_params_alloca(&hwparams);snd_pcm_sw_params_alloca(&swparams);//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, SND_PCM_ACCESS_RW_INTERLEAVED)) < 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, SND_PCM_ACCESS_RW_INTERLEAVED)) < 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);}chirp_size=linear_windowed_chirp(chirp,1000000);/// register playback callbackerr = 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*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 callbackerr = 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);}//start captureif ((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);}//start playbackif (snd_pcm_state(playback_handle) == SND_PCM_STATE_PREPARED) {err = snd_pcm_start(playback_handle);if (err < 0) {printf("Start error: %s\n", snd_strerror(err));exit(EXIT_FAILURE);}}//wait until all samples aren't transmittedprintf("Waiting for transmitt all samples\n");while(cperiod<10) {sleep(1);printf(".");}printf("\nData transmitted... \ncorrelating...\n");for(n=0; n < (SIGNAL_SAMPLES - chirp_size);n++){ //spocita korelaci pro mozna spozdenir=0;for(m=chirp_size;m > 0;m--) r += chirp[m]*signal[m+n]; // reverse echo paterncorrelation[n]=abs(r);}printf("\nFinding echos...\n");r=0;for(n=0; n < (SIGNAL_SAMPLES - chirp_size);n++){ //najde nejvetsi korelaceif (r < correlation[n]){delay[1] = n;r = correlation[n];}}out=fopen("./output.txt","w");for(i=0;i<=100000;i++) fprintf(out,"%6d %6d %6d %6.2f\n",i,chirp[i],signal[i],correlation[i]);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;}