// file: $SPEECH_HOMEWORK4/hw4/class/snr_ratio/v1.0/snr_cal_4.cc
//

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

// method: calculate_snr_cc
//
// arguments:
//  float_4** cdf (input) the cdf of the channels
//  float_4** energy (input) the energy of the channels
//  int_4 num_energy (input) the number of energy
//  float_4* max (input) the maximum energy for each channel
//  float_4* min (input) the minimum energy for each channel
//  float_4* mean (input) the mean energy for each channel
//  float_4 snr (output) the snr for each channel
//
// return: a logical_1 indicating status
//
logical_1 Signal::calculate_snr_cc(int_4** cdf_a, float_4** energy_a,
				   int_4 num_energy_a, float_4* max_a,
				   float_4* min_a, float_4** mean_a,
				   float_4* snr_a) {
  
  // check arguments
  //
  if (snr_a == (float_4*)NULL) {
    error_handler_cc((char_1*)"calculate_snr_cc",
		     (char_1*)"output memory is not allocated");
  }

  // calculate the bin number of the signal and noise using the
  // thresholds
  //
  int_4 sbin = (int_4) (signal_threshold_d * num_energy_a);
  int_4 nbin = (int_4) (noise_threshold_d * num_energy_a);
  
  // loop over all channels
  //
  for (int_4 channel=0;channel < num_chans_d; channel++) {

    // find the noise energy using the noise threshold
    //
    float_4 noise = min_a[channel];
    int_4 index = cdf_a[0][channel];
    int_4 bin = 0;

    while (index < nbin) 
      index = cdf_a[++bin][channel];

    // retrieve the mean energy as the noise
    //
    noise = mean_a[bin][channel];

    // now it's time to find the signal energy
    //
    float_4 signal = min_a[channel];
    
    while (index < sbin) 
      index = cdf_a[++bin][channel];

    // retrieve the mean energy as the noise
    //
    signal = mean_a[bin][channel];

    // calculate the SNR
    //
    snr_a[channel] = (float_4) (10 * log10((signal-noise) / noise));
  }

  // exit gracefully
  //
  return ISIP_TRUE;
  
}