/* sound_read.c -- Write samples to a SoundStream. */

#include <stdio.h>
#include <math.h>
#include "sound.h"


/* Returns: 2 for success, 0 for error or eof. */
int sound_read_short( SoundStream *pSS, short *p_n ) {
  int msb, lsb;

  if( pSS->little_endian ) {
    lsb = getc( pSS->byte_stream );
    msb = getc( pSS->byte_stream );
  } else {
    msb = getc( pSS->byte_stream );
    lsb = getc( pSS->byte_stream );
  }
  if( msb < 0  ||  lsb < 0 ) {
    return( 0 );
  }
  *p_n = msb * 256 + lsb;
  return( 2 );
}


/* Returns: 2 for success, 0 for error or eof. */
int read_sample( SoundStream *pSS, double *p_sample ) {
  short y, readed;

  if( readed = sound_read_short( pSS, &y ) ) {
    *p_sample = decode_sample( y );
  }
  return( readed );
}


/* Returns: 4 for success, 0 for error or eof. */
int read_LR_short( SoundStream *pSS, short *p_left, short *p_right ) {
  int readed;

  readed = sound_read_short( pSS, p_left ) + 
           sound_read_short( pSS, p_right );
  return( readed == 4?  4 : 0 );
}


/* Read 4 bytes, store into a signed long, however big that is.
   Returns: 4 for success, 0 for error or eof.
*/
int sound_read_32bit( SoundStream *pSS, long *p_n ) {
  short msw;
  unsigned short lsw;
  int readed;

  if( pSS->little_endian ) {
    readed = sound_read_short( pSS, &lsw )
	    + sound_read_short( pSS, &msw );
  } else {
    readed = sound_read_short( pSS, &msw )
	    + sound_read_short( pSS, &lsw );
  }
  if( readed == 4 ) {
    *p_n = msw * 65536 + lsw;
    return( readed );
  } else {
    return( 0 );
  }
}


/* Returns: 4 for success, 0 for error or eof. */
int read_LR( SoundStream *pSS, double *p_left, double *p_right ) {
  int readed;

  readed = read_sample( pSS, p_left ) + read_sample( pSS, p_right );
  return( readed == 4?  4 : 0 );
}