// file: lecture_17/gen_signal/example.cc
//

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

// function: main
//
// This is a simple program that generates a sinewave.
//
int main(int argc, const char** argv) {

  // open a file for writing
  //
  FILE* fp = fopen(argv[1], "w");
  if (fp == (FILE*)NULL) {
    fprintf(stdout, "**> (%s): error opening file %s\n",
	    argv[0], argv[1]);
  }

  // decode the command line arguments
  //
  float fsamp = atof(argv[2]);
  float freq  = atof(argv[3]);
  float ampl  = atof(argv[4]);
  float dur   = atof(argv[5]);

  // echo the command line arguments
  //
  fprintf(stdout, "program name: %s\n", argv[0]);
  fprintf(stdout, "fsamp = %f Hz\n", fsamp);
  fprintf(stdout, "freq  = %f Hz\n", freq);
  fprintf(stdout, "ampl  = %f units\n", ampl);
  fprintf(stdout, "dur   = %f secs\n", dur);

  // create space for the signal
  //
  long num_samples = round(dur * fsamp);
  short int sig[num_samples];

  // loop over all samples
  //
  for (long i = 0; i < num_samples; i++) {

    // compute the argument to sin
    //
    float sum = (float)i / fsamp * freq * M_2PI;
    //    float val = ampl * sin(sum);
    float val = i;

    // clip the signal:
    //  note the range of a short int is [-32768, 32767]
    //
    if (val > MAX_VAL) {
      val = MAX_VAL;
    }
    else if (val < -MAX_VAL) {
      val = -MAX_VAL;
    }

    // assign the value
    //
    sig[i] = (short int)val;
  }

  // write the signal to a file
  //
  long num_written = fwrite(sig, sizeof(short int), num_samples, fp);
  if (num_written != num_samples) {
    fprintf(stdout, "**> (%s): incorrect number of samples written (%d %d)\n",
	    num_written, num_samples);
  }

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

  // exit gracefully
  //
  return(0);
}