// file: csnr_cal_12.cc
//
// this function computes the snr value of the signal in each channel
//

// system include file
//
#include <math.h>

// local include file
//
#include "global_constants.h"
#include "calculate_snr_constants.h"
#include "calculate_snr.h"

// function: calculate_snr_cc
//
// arguments:
//    float*& snr_values_a: (output) snr values
//    float** cdf_a: (input) cdf of the signal
//    int num_chans_a: (input) number of channels
//    float noise_threshold_a: (output) threshold of noise
//    float signal_threshold_a: (output) threshold of signal+noise
//    int debug_mode_a: (input) debug level
//
// return: an int to indicate status
//
// this function calculates the signal to noise ratio using the following
// equation:
//
// SNR = 10 * log10[((Es + En) - En) / En] 
//   
//
int calculate_snr_cc (float*& snr_values_a, float** cdf_a, float** bin_avgs_a,
		      int num_chans_a, float noise_threshold_a,
		      float signal_threshold_a, int debug_mode_a) {

  int noise_flag = FALSE;
  int signal_flag = FALSE;
  float noise_level;
  float signal_level;
  
  for (int j = 0; j < num_chans_a; j++) {

    for (int i = 0; i < CSNR_NUM_BINS; i++) {
      
      if ( (cdf_a[j][i] > noise_threshold_a) && (!noise_flag) ) {
	noise_level = bin_avgs_a[j][i];
	noise_flag = TRUE;
      }
      
      else if ( (cdf_a[j][i] > signal_threshold_a) && (!signal_flag) ) {
	signal_level = bin_avgs_a[j][i];
	signal_flag = TRUE;
      }
    }
    snr_values_a[j] = (float)10.0 * log10((signal_level - noise_level) /
					  noise_level);
    noise_flag = FALSE;
    signal_flag = FALSE;
  }

  if (debug_mode_a > DEBUG_BRIEF) {
    for (int j = 0; j < num_chans_a; j++) {
      fprintf(stdout, "snr [%d] = %.2f\n", j, snr_values_a[j]);
    }
  }

  // exit gracefully
  //
  return TRUE;
}