// file: csnr_cal_4.cc
//
// this function windows the signal
//

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

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

// function: window_signal_cc
//
// arguments:
//    float*& signal_window_a: (input/output) 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 win_type_a: (input) type of window
//    int debug_mode_a: (input) debug level
//
// return: an int to indicate status
//
// this function windows the signal using either hamming window or rectangular
// window using the equation below:
//
// x(k) = x(k) * window(k)
//
// where window(k) = 1 for rectangular window
//       window(k) = 0.54 - 0.46 * cos(2 * pi * k / (N - 1)) for hamming window
// and k = 0 .. N-1
// and N = total signal points
//
//
int window_signal_cc (float*& signal_window_a, int samples_per_win_a,
		      int num_chans_a, int win_type_a, int debug_mode_a) {

  int num_samples = samples_per_win_a * num_chans_a;

  if (win_type_a == CLPC_RCTGL_WIN) {
    for (int chan = 0; chan < num_chans_a; chan++) {
      for (int sample = chan; sample < num_samples; sample += num_chans_a) {
	signal_window_a[sample] *= CLPC_RCTGL_CONST;
      }
    }
  }
  
  else if (win_type_a == CLPC_HAMMING_WIN) {
    
    for (int chan = 0; chan < num_chans_a; chan++) {
      for (int sample = chan; sample < num_samples; sample += num_chans_a) {
	signal_window_a[sample] *= ( 0.54 - 0.46 *  cos( 2 * M_PI *
	   (float)(sample / num_chans_a) / (samples_per_win_a - 1) ) );
      }
    }
  }

  else {
    fprintf(stdout, "No such window type\n");
    return FALSE;
  }
  
  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 :: windowed signal [%d] =  %.6f\n",
		chan, sample, signal_window_a[sample]);
      }
    }
    fprintf(stdout, "\n");
  }
  
  // exit gracefully
  //
  return TRUE;
}