// file: fbc_detect.C
//
// Detect feedback in frame of data.
//

#include "fbc.h"


int fbc_detect_C (double* fft_out, float threshold, float bandwidth,
		  float& center_freq,
		  float max, int fft_num, float sample_frequency) {

  //  Declare local variable for the magnitude of the fft
  //
  double* fft_mag = (double*)malloc(fft_num/2 * sizeof(double));
  
  //  Declare local variable for counting the max number of samples
  //
  int max_sample_num = 0;
  
  //  Compute the magnitude of the fft,
  //  The fft is in real and imaginary parts,  0: real 1: imaginaries, 2:
  //  3: imaginary, ...   2*k are reals, 2*k+1 are imaginaries.
  //
  for (int k = 0; k<fft_num/2; k++){
      fft_mag[k] = sqrt(fft_out[2*k]*fft_out[2*k] + fft_out[2*k+1]*fft_out[2*k+1]);
    }


  
  
  for(int j=0;j<fft_num/2;j++){
//       printf("fft_num: %d, real: %d, img: %d\n", j,fft_out[2*j],fft_out[2*j+1]);
//       printf("single detect, fft_num: %d, mag: %f\n", j,fft_mag[j]);
    }
  

  //  Set the first sample to the maximum, and set the max counter to 0 (1st sample)
  //
  max = fft_mag[0];
  max_sample_num = 0;

 
  /*
  printf("\n");
  printf("fft_out mag in detect funct:\n");
  for (int i = 0; i < fft_num/2; i++) {
      printf("%f\n",fft_mag[i]);
  }
  printf("\n");
  */

  //  Loop through frame to find max
  //
  for (int current_sample_num=1; current_sample_num<fft_num/2; current_sample_num++){
    if (fft_mag[max_sample_num] < fft_mag[current_sample_num]) {
       max = fft_mag[current_sample_num];
       max_sample_num = current_sample_num;
    }
  }

  // Determine center frequency of the max sample
  //
  center_freq = max_sample_num * sample_frequency / fft_num;

  //  printf("this is max: %f\n", max);
  //  printf("the position of the center freq is: %d\n", max_sample_num);
  //   printf("detect single, center freq: %f\n", center_freq);
  
  // exit gracefully
  //
  return L_TRUE;

}