// file: clpc_cal_2.cc
//
// this function debiases 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: debias_signal_cc
//
// arguments:
//    float*& signal_window_a: (input/output) input signal and output
//                             debiased signal
//    int num_chans_a: (input) number of channels
//    int samples_per_win_a: (input) number of samples in the window
//    int debug_mode_a: (input) debug mode
//
// return: the status of the routine
//
// this function debiases the signal using the equation below:
//  x(k) = x(k) - avg
//
// where avg = 1/N * sum ( x(n) ) from 0 .. N-1
// and k = 0 .. N-1
// and N = total signal points
//
//
int debias_signal_cc (float*& signal_window_a, int samples_per_win_a,
		      int num_chans_a, int debug_mode_a) {

  int num_samples = samples_per_win_a * num_chans_a;
  
  // compute the average signal value and subtract it from every
  // original signal value
  //
  float signal_avg = 0;
  
  for (int chan = 0; chan < num_chans_a; chan++) {
    for (int sample = chan; sample < num_samples; sample += num_chans_a) {
      signal_avg += signal_window_a[sample];
    }
    signal_avg /= samples_per_win_a;
  
    // subtract this from sample values
    //
    for (int sample = chan; sample < num_samples; sample += num_chans_a) {
      signal_window_a[sample] -= signal_avg;
    }
  }

  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 :: debias signal [%d] = %.6f\n", chan,
		sample,	signal_window_a[sample]);
      }
    }
    fprintf(stdout, "\n");
  }

  // exit gracefully
  //
  return TRUE;
}