// file: clpc_cal_3.cc
//
// this function filters the signal 
//

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

// local include file
//
#include "global_constants.h"
#include "calculate_lpc_constants.h"
#include "calculate_lpc.h"

// function: pre_emphasize_signal_cc
//
// arguments:
//    float*& signal_window_a: (input/output) input buffer containing the
//                            signal to be pre-emphasized and output buffer
//                            containing the pre-emphasized signal
//    float*& prev_sig_val_a: (input/output) previous frame last signal value
//    int samples_per_win_a: (input) number of samples per window
//    int num_chans_a: (input) number of channels
//    float preemp_val_a: (input) pre-emphasis constant
//    int debug_mode_a: (input) debug level
//
// return: an int to indicate status
//
// this function filters the signal using the equation below:
//   x(k) = x(k) - a * x(k-1);
//
// where a is the filter constant
// and k = 0 .. N-1
// and N = total signal points
//
//
int pre_emphasize_signal_cc (float*& signal_window_a, float*& prev_sig_val_a,
			     int samples_per_win_a, int num_chans_a, 
			     float preemp_val_a, int debug_mode_a) {

  int num_samples = samples_per_win_a * num_chans_a;

  // keep a copy of the original data
  //
  float* temp_window = new float[num_samples];

  for (int sample = 0; sample < num_samples; sample++) {
    temp_window[sample] = signal_window_a[sample];
  }

  // calculate the pre-emphasis signal
  //
  for (int chan = 0; chan < num_chans_a; chan++) {
    signal_window_a[chan] = temp_window[chan] - preemp_val_a *
      prev_sig_val_a[chan];
  }

  for (int chan = 0; chan < num_chans_a; chan++) {
    for (int sample = num_chans_a; sample < num_samples;
	 sample += num_chans_a) {
      signal_window_a[sample] = temp_window[sample] -
	preemp_val_a * temp_window[sample-num_chans_a];
    }
  }

  for (int chan = 0; chan < num_chans_a; chan++) {
    prev_sig_val_a[chan] = signal_window_a[num_samples-num_chans_a+chan];
  }
  
  if (debug_mode_a > DEBUG_FULL) {
    for (int chan = 0; chan < num_chans_a; chan++) {
      for (int sample = chan; sample < num_samples; sample += num_chans_a) {
	fprintf(stdout, "chan %d :: pre-emphasized signal [%d] = %.6f\n",
		chan, sample, signal_window_a[sample]);
      }
      fprintf(stdout, "\n");
    }
  }

  // delete temp buffer
  //
  if (temp_window != (float*)NULL) {
    delete [] temp_window;
    temp_window = (float*)NULL;
  }
  
  // exit gracefully
  //
  return TRUE;
}