// file: csnr_cal_2.cc
//
// this function filters the signal 
//

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

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

// function: pre_emphasize_signal_cc
//
// arguments:
//    float* pre_emphasized_signal_a: (output) pre-emphasized the signal
//    float* signal_window_a: (input) buffer contain the signal to
//                             be pre-emphasized
//    int samples_per_win_a: (input) number of samples per window
//    int num_chans_a: (input) number of channels
//    int debug_mode_a: (input) debug level
//
// return: an int to indicate status
//
// this function filters the signal using p(z) = 1 - u * z ^ (-1) filter
//
//
int pre_emphasize_signal_cc (float*& pre_emphasized_signal_a,
			     float* signal_window_a, int samples_per_win_a,
			     int num_chans_a, float*& signal_prev_frame_a,
			     int debug_mode_a) {

  int num_samples = samples_per_win_a * num_chans_a;

  for (int j = 0; j < num_chans_a; j++) {
    pre_emphasized_signal_a[j] = signal_window_a[j] -
      0.95 * signal_prev_frame_a[j];
  }

  for (int j = 0; j < num_chans_a; j++) {
    for (int i = num_chans_a + j; i < num_samples; i += num_chans_a) {
      pre_emphasized_signal_a[i] = signal_window_a[i] -
	0.95 * signal_window_a[i-num_chans_a];
    }
  }

  for (int j = 0; j < num_chans_a; j++) {
    signal_prev_frame_a[j] = signal_window_a[num_samples-num_chans_a+j];
  }
  
  if (debug_mode_a > DEBUG_FULL) {
    for (int j = 0; j < num_chans_a; j++) {
      for (int i = j; i < num_samples; i += num_chans_a) {
	fprintf(stdout, "chan %d :: pre-emphasized signal [%d] =  %.2f\n", j,
		i/num_chans_a, pre_emphasized_signal_a[i]);
      }
    }
    fprintf(stdout, "\n");
  }

  // exit gracefully
  //
  return TRUE;
}