// file: csnr_file_0.cc
//
// this function reads in the data 
//

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

// local include file
//
#include "global_constants.h"
#include "calculate_snr_constants.h"
#include "calculate_snr.h"

// function: read_signal_cc
//
// arguments:
//    float*& signal_window_a: (output) buffer contain the signal
//    int num_chans_a: (input) number of channels
//    int start_time_a: (input) starting time of window
//    char* datafile_a: (input) name of data file
//    int debug_mode_a: (input) debug level
//
// return: an int to indicate status
//
// this function parses the command line arguments
//
//
int read_signal_cc (float*& signal_window_a, int num_chans_a,
		    int start_sample_a, int end_sample_a,
		    int end_file_sample_a, char* datafile_a,
		    int debug_mode_a) {

  // open the file
  //
  FILE* fp = fopen(datafile_a, "r");

  if (fp == (FILE*)NULL) {
    fprintf(stdout, "Unable to open data file\n");
    return FALSE;
  }

  // make sure that start and end sample are within bounds
  //
  int new_start = start_sample_a;
  int new_end = end_sample_a;
  int num_samples = 0;
  
  if (start_sample_a < 0) {

    // pad it with 0s if window starts before file starts
    //
    for (int i = start_sample_a; i < 0; i++) {
      signal_window_a[num_samples++] = 0;
    }
    new_start = 0;
  }
  
  if (end_sample_a > end_file_sample_a) {
    new_end = end_file_sample_a;
  }
  
  if (new_start > new_end) {
    //    fprintf(stdout, "start sample is greater than end sample\n");
    return FALSE;
  }

  // seek to the point in the file we want to read the data
  //
  fseek(fp, (int)new_start * CSNR_BYTES_PER_SAMPLE * num_chans_a,
	SEEK_SET);
  
  int samples_read = new_end - new_start;

  short int* temp_values = new short int[samples_read];

  int items_read = fread(temp_values, sizeof(short int), samples_read, fp);
  
  if (items_read != samples_read) {
    return FALSE;
  }
  
  for (int i = 0; i < samples_read; i++) {
  
    // convert short int to floating point values
    //
    signal_window_a[num_samples++] = (float)temp_values[i];
  }

  // pad it with 0s if window ends after file ends
  //
  if (end_sample_a > end_file_sample_a) {
    for (int i = end_file_sample_a; i < end_sample_a; i++) {
      signal_window_a[num_samples++] = 0;
    }
  }

  if (debug_mode_a > DEBUG_FULL) {
    for (int j = 0; j < num_chans_a; j++) {
      for (int i = j; i < num_samples; i += num_chans_a) {
	fprintf(stdout, "chan %d :: signal data [%d] =  %d\n", j,
		i/num_chans_a, (short int)signal_window_a[i]);
      }
    }
    fprintf(stdout, "\n");
  }
  
  // close the file
  //
  fclose(fp);

  if (temp_values != (short int*)NULL) {
    delete [] temp_values;
    temp_values = (short int*)NULL;
  }
  
  // exit gracefully
  //
  return TRUE;
}