// file: $SPEECH_HOMEWORK4/hw4/class/snr_ratio/v1.0/snr_auto_0.cc
//

// isip include files
//
#include <string.h>
#include <math.h>
#include "signal_noise_ratio.h"
#include "signal_noise_ratio_constants.h"
#include <integral.h>
#include <integral_constants.h>

// method: perform_lp_cc
//
// arguments:
//  float_4* buffer (input) signal to perform autocorrelation on
//  float_4**& auto_corr_values (output) autocorrelation values
//  int_4 samples_per_window (input) the number of samples in one window
//
// return: a logical_1 indicating status
//
logical_1 Signal::perform_autocorrelation_cc(float_4* buffer_a,
					     float_4**& auto_corr_values_a,
					     int_4 samples_per_window_a) {

  // loop over the channels
  //
  for (int_4 i=0;i<num_chans_d;i++) {

    // loop over the value of k where k = 0 to the lp order
    //
    for (int_4 k=0; k<=lp_order_d; k++) {
          
      // loop over the samples
      //
      for (int_4 j=0;j<samples_per_window_a-k;j++) {
	
	// calculate the autocorrelation values
	//
	auto_corr_values_a[i][k] += buffer_a[j*num_chans_d+i] *
	  buffer_a[(j+k)*num_chans_d+i];
      }
    }
  }

  if (debug_level_d > 1) {
    for (int_4 i = 0; i < num_chans_d; i++) {
      for (int_4 j = 0; j <= lp_order_d; j++) {
        fprintf(stdout, "chan %ld :: autocorrelation values [%ld] =  %.6f\n",
		i, j, auto_corr_values_a[i][j]);
      }
    }
    fprintf(stdout, "\n");
  }
  
  // exit gracefully
  //
  return ISIP_TRUE;
  
}