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// jednoduchy algoritmus krizove korelace

// copile gcc correlation.c -lm -o correlation

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

#define SAMPLES  1000

#define SIGNAL_SAMPLES  SAMPLES*20

int sample[SAMPLES];

int signal[SIGNAL_SAMPLES];

double correlation[SIGNAL_SAMPLES];

int obdelnik(int *pole, int delka_pole, int delka_pulsu, int spozdeni) //generuje testovaci lichobeznikovy puls  do zadaneho pole

{

int i;

int value=1;

  for (i=0; i <= delka_pole; i++) { 

    if (i < spozdeni && i < delka_pole) pole[i]=value;

    if ((i > spozdeni) && (i < (spozdeni+10))) pole[i] = value++;

    if (i < (spozdeni+delka_pulsu+10) && i > (spozdeni+10) && i < delka_pole) pole[i]= value;      

    if (i < (spozdeni+delka_pulsu+20) && i > (spozdeni+delka_pulsu+10) && i < delka_pole) pole[i] = value--;      

    if (i > (spozdeni+delka_pulsu+20) && i < delka_pole) pole[i]=value;

  }

}

int linear_chirp(int *pole, int delka_pole, int delka_pulsu, int spozdeni){  // vygeneruje linearni chirp a vzorky ulozi do pole

static const double pi = 3.141592653589793238462643383279502884197; // Archimedes constant pi

static const float f0 = 0.01;

static const float k = 0.0001;

int t;

float ble;

  if((spozdeni+delka_pulsu) < delka_pole)

    for(t=0;t < delka_pulsu;t++) pole[spozdeni+t] = round ( 100*sin(2*pi*t*(f0+(k/2)*t)) );

  else return 0;

}

int exp_chirp(int *pole, int delka_pole, int delka_pulsu, int spozdeni){  // vygeneruje linearni chirp a vzorky ulozi do pole

static const double pi = 3.141592653589793238462643383279502884197; // Archimedes constant pi

static const float f0 = 0.01;

static const float k = 0.0001;

int t;

float ble;

  if((spozdeni+delka_pulsu) < delka_pole)

    for(t=0;t < delka_pulsu;t++) pole[spozdeni+t] = round ( 100*sin(2*pi*t*(f0+(k/2)*t)) );

  else return 0;

}

int main (void)

{

   int i,n,m,delay;

   double r;

   linear_chirp(sample,SAMPLES,100,0);			// vyrobi vzorek signalu

   linear_chirp(signal,SIGNAL_SAMPLES,500,1000);			// vyrobi signal ve kterem se vzorek hleda

   for(n=0; n < (SIGNAL_SAMPLES - SAMPLES);n++){			//spocita korelaci pro mozna spozdeni

     r=0;

     for(m=0;m < SAMPLES;m++) r += sample[m]*signal[m+n];

     correlation[n]=r;

   }

   r=0;

   for(n=0; n < (SIGNAL_SAMPLES - SAMPLES);n++){			//najde nejvetsi shodu (pro nazornost v samostatnem cyklu)

     if (r < correlation[n]){

       delay = n;

       r = correlation[n];

     }

   }

   for(i=0;i<SAMPLES;i++)

   {

//     fprintf(stdout,"%3u ",i);	 		// vypise cislo bunky v poli (spozdeni)

     fprintf(stdout,"%2i ",sample[i]);

//     fprintf(stdout,"%2d ",signal[i]);

//     fprintf(stdout,"%3.2f\n",correlation[i]);		// vypise hodnotu korelace nejvissi cislo je nejvetsi korelace.

   }

   fprintf(stdout,"\nvzorek v signalu zacina na miste: %3u \n",delay);

  exit(1);

}