// file: example.cc
//
// generate a sinewave to a file
//

// include files
//
#include "example.h"

// main program
//
int main(int argc, char** argv) {

  // check the number of command line arguments
  //
  if (argc < NARGS) {
    fprintf(stdout, "**> insufficient number of arguments (%d)\n", argc);
    return(-1);
  }

  // get the command line arguments
  //
  FILE* fp = fopen(argv[1], "w");
  if (fp == (FILE*)NULL) {
    fprintf(stdout, "error opening file\n");
    return(-1);
  }

  float frequency = atof(argv[2]);
  fprintf(stdout, "frequency = %f Hz\n", frequency);
  float sample_frequency = atof(argv[3]);
  fprintf(stdout, "sample_frequency = %f Hz\n", sample_frequency);
  float total_time = atof(argv[4]);
  fprintf(stdout, "total time = %f Hz\n", total_time);
  float amplitude = atof(argv[5]);
  fprintf(stdout, "amplitude = %f Hz\n", amplitude);

  // convert time to samples
  //
  long N = (long)round(total_time * sample_frequency);
  fprintf(stdout, "the number of samples is %d\n", N);

  // loop over the samples and generate a sinewave
  //
  //  for (float ctime = 0; ctime < total_time; ctime += 1.0 / sample_frequency) {
  for (long i = 0; i < N; i++) {

    // calculate a value
    //
    //    fprintf(stdout, "(%d) (%f secs): %f\n", i, (float)i / sample_frequency, sum);
    float sum = amplitude * sin(2.0 * M_PI * frequency * (float)i / sample_frequency);

    // write this to a file
    //
    short int ival = (short int)round(SCALE * sum);
    fprintf(stdout, "(%d) (%f secs): %f (%d)\n", i, (float)i / sample_frequency,
	    sum, ival);
    if (fwrite(&ival, sizeof(short int), 1, fp) != 1) {
      fprintf(stdout, "*> error writing data (%d %d)\n", i, ival);
    }
  }

  // close the file
  //
  fclose(fp);

  // open the file again
  //
  FILE* fp2 = fopen(argv[1], "r");
  if (fp2 == (FILE*)NULL) {
    fprintf(stdout, "error opening file\n");
    return(-1);
  }

  fprintf(stdout, "... reading back ...\n");
  long i = 0;
  short int ival;
  while (fread(&ival, sizeof(short int), 1, fp2) == 1) {
    fprintf(stdout, "(%d) (%f secs): %f (%d)\n", i, (float)i / sample_frequency,
	    (float)ival, ival);
    i++;
  }

  // exit gracefully
  //
  return 0;
}