/*

convert to WAV audio encoding

handles only 8000 Hz. 16-bit single channel data

R. Perry, March 2014

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <math.h>
#include <errno.h>

#include "audio.h"

/* global argv[0] for error messages */

char *progname;

/* input buffer for encoding */

double *buf = NULL;
int size = 0;
int n = 0;

int push( double s)
{
  if( n == size)
  {
    int newsize = 1.5*size + 65536;

    if( newsize > 1048576)
    {
      fprintf( stderr, "%s: buffer limit reached\n", progname);
      return 1;
    }

    double *newbuf = realloc( buf, newsize*sizeof(double));

    if( newbuf == NULL)
    {
      fprintf( stderr, "%s: realloc() failed\n", progname);
      exit(1);
    }

    size = newsize;
    buf = newbuf;
  }

  buf[n++] = s;

  return 0;
}

/* convert text/PCM samples to WAV file */

void do_encode( void)
{
  double s;

  while( scanf( "%lf", &s) == 1)
    if( push(s)) break;

  if( n == 0)
  {
    fprintf( stderr, "%s: empty input\n", progname);
    exit(2);
  }

  int *data = malloc( n * sizeof(int));

  if( data == NULL)
  {
    fprintf( stderr, "%s: malloc() failed\n", progname);
    exit(3);
  }

  double max = fabs( buf[0]);

  for( int i = 1; i < n; ++i)
  {
    double t = fabs( buf[i]);
    if( t > max) max = t;
  }

  if( max == 0) max = 1;

  for( int i = 0; i < n; ++i)
  {
    double t = 32767.0*(buf[i]/max);
    if( t > 0) t += 0.5; else t -= 0.5;
    data[i] = t;
  }

  write_wav( n, data, 8000);
}

int main( int argc, char *argv[])
{
  progname = argv[0];

  do_encode();

  return 0;
}