// file: read_0.C
//

#include "./process_data.h"

// important definitions
//
static float last_sample_frequency = (float)-1.0;
static float last_frame_duration = (float)-1.0;
static float last_window_duration = (float)-1.0;

static short int* tmp_buf = NULL;

//-----------------------------------------------------------------------------
// function: read_data_C
//
// arguments:
//  float* buffer:		(output) input data
//  FILE* fp:			(input)  input file pointer
//  int frame_number:		(input)  the number of the frame
//  float sample_frequency:	(output) sample frequency of the signals
//  float frame_duration:	(output) frame_duration of the analysis
//  float window_duration:	(output) window_duration of the analysis
//
// returns:
//  L_TRUE if no error was encounterd
//
// reads one analysis window from a file
//-----------------------------------------------------------------------------
int read_data_C(float* buffer, FILE* fp, int frame_number,
		float sample_frequency,	float frame_duration,
		float window_duration) {

  // convert to integer
  //
  int frame_dur_samples = (int)round_C(frame_duration * sample_frequency);
  int window_dur_samples = (int)round_C(window_duration * sample_frequency);

  // allocate space
  //
  if ((last_sample_frequency != sample_frequency) ||
      (last_frame_duration != frame_duration) ||
      (last_window_duration != window_duration)) {
    if (tmp_buf != NULL)
      {free(tmp_buf);}
    tmp_buf = (short int*)malloc(window_dur_samples * BYTES_PER_SAMPLE);
  }

  // position the file
  //
  int offset = frame_number * frame_dur_samples - 
    (int)round_C((window_duration - frame_duration) / 2.0 * sample_frequency);
  
  if (offset < (int)0)
    {rewind(fp);}
  else
    {fseek(fp, offset * BYTES_PER_SAMPLE, 0);}

  // compute the number of samples to read
  //
  int num_samples_to_read;
  int num_samples_read;

  if (offset >= 0)
    {num_samples_to_read = window_dur_samples;}
  else
    {num_samples_to_read = window_dur_samples + offset;}

  // read the data
  //
  if (num_samples_to_read > 0) {
    num_samples_read = fread(tmp_buf, BYTES_PER_SAMPLE,
			     num_samples_to_read, fp);
  }

  // convert it to floats
  //
  for (int sample_num=0; sample_num<window_dur_samples; sample_num++) {

    if (offset < 0) {
      if (sample_num < -offset)
	{buffer[sample_num] = 0.0;}
      else
	{buffer[sample_num] = (float)tmp_buf[sample_num + offset];}
    }

    else {
      if (sample_num < num_samples_read)
	{buffer[sample_num] = (float)tmp_buf[sample_num];}
      else
	{buffer[sample_num] = (float)0.0;}
    }
  }

  // save parameters
  //
  last_sample_frequency = sample_frequency;
  last_frame_duration = frame_duration;
  last_window_duration = window_duration;

  // exit gracefully
  //
  if (num_samples_read > (int)0)
    {return L_TRUE;}
  else
    {return L_FALSE;}
}