/* This program reads a wave file from the standard input
   and verifies that it has the
   correct format, which for us is monaural, 8 bits per sample,
   and 11025 samples/per second. If the file is incorrect, the
   program prints an error message and exits.  If the file is
   correct, it prints the sampled data to standard output, using
   the following format:
   
   0   0.834
   1   0.876
   .
   .
   .

   The bytes making up the data sample are translated from the
   range 0..255 to the range -1 to 1.

   Note an idiosyncrasy in the use of getchar. This function returns
   an int, so when we read a byte with it, we get a value between 0
   and 255.  However when we assign it to a char, and then back to
   an int, we get a value between -128 and 127, so we need to be careful!
*/

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
main()
{
  char buf[16];
  int intbuf[4],sample;
  int i,length;
  float sampleval;
  for(i=0;i<16;i++)
    buf[i]=getchar();
  /* Check to see if this contain the correct header information
     for a wave file. */
  if((buf[0]!='R')||(buf[1]!='I')||(buf[2]!='F')||(buf[3]!='F')||
     (buf[8]!='W')||(buf[9]!='A')||(buf[10]!='V')||(buf[11]!='E')||
     (buf[12]!='f')||(buf[13]!='m')||(buf[14]!='t')||(buf[15]!=' '))
    {
      fprintf(stderr,"Bad header for WAV file.\n");
      exit(0);
    }
  for(i=0;i<16;i++)
    buf[i]=getchar();
  /* Check chunk length */
  if(((int)buf[0]!=16)||((int)buf[1]!=0)||((int)buf[2]!=0)||((int)buf[3]!=0))
    {
      fprintf(stderr,"Can't process file with this data format(1).\n");
      exit(0);
    }
  /* Check for compression and single-channel */
   if(((int)buf[4]!=1)||((int)buf[5]!=0)||((int)buf[6]!=1)||((int)buf[7]!=0))
     {
       fprintf(stderr,"Can't process file with this data format.(2)\n");
       exit(0);
     }
   /* Check sample rate */
    if(((int)buf[8]!=17)||((int)buf[9]!=43)||((int)buf[10]!=0)||((int)buf[11]!=0))
      {
	 fprintf(stderr,"Can't process file with this sampling rate.\n");
	 exit(0);
      }
    /* Check number of bits per sample */
    if(((int)buf[12]!=17)||((int)buf[13]!=43)||((int)buf[14]!=0)||((int)buf[15]!=0))
      {
	 fprintf(stderr,"Can't process file with this number of bits per sample.\n");
	 exit(0);
      }
    for(i=0;i<8;i++)
      buf[i]=getchar();
    if((buf[4]!='d')||(buf[5]!='a')||(buf[6]!='t')||(buf[7]!='a'))
      {
	fprintf(stderr,"Can't process file with this data format(3).\n");
	exit(0);
      }
    /* Now everything is all right.  The next four bytes contain
       the number of samples. */
    length=0;
    for(i=0;i<4;i++)
      {
	intbuf[i]=getchar();
      }
    for(i=3;i>=0;i--)
      length=256*length+intbuf[i];
    /*just to check 
      printf("Number of samples: %d\n",length); */
    for(i=0;i<length;i++)
      {
	sample=getchar();
	sampleval=(2.0*sample)/256-1;
	printf("%d\t%g\n",i,sampleval);
      }
}