// file: $SPEECH_HOMEWORK4/hw4/class/snr_ratio/v1.0/snr_preem_0.cc
//

// isip include files
//
#include "signal_noise_ratio.h"
#include "signal_noise_ratio_constants.h"

// method: perform_pre_emphasis_cc
//
// arguments:
//  float_4* buffer (input/output) the signal to pre emphasize
//  int_4 samples_per_window (input) the number of samples per window
//
// return: a logical_1 indicating status
//
logical_1 Signal::perform_pre_emphasis_cc (float_4* buffer_a,
					   int_4 samples_per_window_a) {

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

    // store the x(n) and x(n-1)
    //
    float_4 n = 0;
    float_4 n_minus = 0;
    
    // loop over the samples
    //
    for (int_4 j=0;j<samples_per_window_a;j++) {

      // get x(n)
      //
      n = buffer_a[j*num_chans_d+i];
      
      // calculate the pre-emphasized value
      //
      buffer_a[j*num_chans_d+i] = n - pre_emphasize_value_d
	* n_minus;

      // store x(n) as x(n-1) for the next sample
      //
      n_minus = n;
    }
  }

  if (debug_level_d > 1) {
    for (int_4 i=0; i<num_chans_d; i++) {
      for (int_4 j=0; j<samples_per_window_a;j++) {
	fprintf(stdout, "chan %ld :: pre-emphasized signal [%ld] =  %.2f\n", i,
		j, buffer_a[j*num_chans_d+i]);
      }
    }
  }

  // exit gracefully
  //
  return ISIP_TRUE;
  
}