// file: clpc_cal_6.cc
//
// this function computes the lp coefficients of a signal
//

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

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

// function: calculate_lp_cc
//
// arguments:
//    float**& lp_signal_a: (output) buffer contains the dft of the signal
//    float*& lp_gain_a: (output) predictor gain
//    float* signal_window_a: (input) buffer of signal
//    int samples_per_win_a: (input) number of samples per window
//    int num_chans_a: (input) number of channels
//    int lp_order_a: (input) type of window
//    int debug_mode_a: (input) debug level
//
// return: an int to indicate status
//
// this function calculates the lpc of a signal using the equation below:
//
//
int calculate_lp_cc (float**& lp_spect_coeffs_a, float*& lp_gain_a,
		     float* signal_window_a, int samples_per_win_a,
		     int num_chans_a, int lp_order_a, int debug_mode_a) {

  float** autocorr_coeffs = new float*[num_chans_a];
  float** lp_pred_coeffs = new float*[num_chans_a];
  for (int chan = 0; chan < num_chans_a; chan++) {
    autocorr_coeffs[chan] = new float[lp_order_a + 1];
    memset(autocorr_coeffs[chan], 0, sizeof(float) * (lp_order_a + 1));
    lp_pred_coeffs[chan] = new float[lp_order_a + 1];
    memset(lp_pred_coeffs[chan], 0, sizeof(float) * (lp_order_a + 1));
  }
  
  // calculate the autocorrelation coefficients
  //
  calculate_autocorr_cc(autocorr_coeffs, signal_window_a, samples_per_win_a,
			num_chans_a, lp_order_a, debug_mode_a);

  // initialize variables for the predictor coefficients and the gain
  //
  memset(lp_gain_a, 1, sizeof(float) * num_chans_a);
  
  // compute the lp predictor coefficients
  //
  calculate_pred_coeff_cc(lp_pred_coeffs, lp_gain_a, autocorr_coeffs,
			  num_chans_a, lp_order_a, debug_mode_a);
    
  // compute the spectrum of the lp signal
  //
  calculate_spect_cc(lp_spect_coeffs_a, lp_pred_coeffs, lp_gain_a,
		     samples_per_win_a, num_chans_a, lp_order_a, debug_mode_a);
  
  if (debug_mode_a > DEBUG_FULL) {
    for (int chan = 0; chan < num_chans_a; chan++) {
      for (int sample = 0; sample < samples_per_win_a; sample++) {
	fprintf(stdout, "chan %d :: lp signal [%d] =  %.6f\n",
		chan, sample, lp_spect_coeffs_a[chan][sample]);
      }
    }
    fprintf(stdout, "\n");
  }
  
  // delete scratch space
  //
  if (autocorr_coeffs != (float**)NULL) {
    for (int chan = 0; chan < num_chans_a; chan++) {
      if (autocorr_coeffs[chan] != (float*)NULL) {
	delete [] autocorr_coeffs[chan];
	autocorr_coeffs[chan] = (float*)NULL;
      }
    }
    delete [] autocorr_coeffs;
    autocorr_coeffs = (float**)NULL;
  }

  if (lp_pred_coeffs != (float**)NULL) {
    for (int chan = 0; chan < num_chans_a; chan++) {
      if (lp_pred_coeffs[chan] != (float*)NULL) {
	delete [] lp_pred_coeffs[chan];
	lp_pred_coeffs[chan] = (float*)NULL;
      }
    }
    delete [] lp_pred_coeffs;
    lp_pred_coeffs = (float**)NULL;
  }
 
  // exit gracefully
  //
  return TRUE;
}