/****************************************************************************
|                         Digital Audio Processor
|                         =======================
|
| Filename    : ieee.c
|
| Object      : None
|
| Description : Audiofile replacement code for linux
|
| (c) Richard Kent 1997
|
| $Id: ieee.c,v 1.1 2003/09/10 00:06:24 rk Exp $
|
****************************************************************************/

static char ieee_c [] = "$Id: ieee.c,v 1.1 2003/09/10 00:06:24 rk Exp $";

#include "ieee.h"

#ifndef HUGE_VAL
#define HUGE_VAL HUGE
#endif

#define FloatToUnsigned(f) \
  ((unsigned int)(((int)(f - 2147483648.0)) + 2147483647L) + 1)
#define UnsignedToFloat(u)\
  (((double)((int)(u - 2147483647L - 1))) + 2147483648.0)

/*---------------------------------------------------------------------------
| FUNCTION convertToIeeeExtended
---------------------------------------------------------------------------*/
void convertToIeeeExtended (double num,unsigned char *bytes)
{
  int sign;
  int expon;
  double fMant;
  double fsMant;
  unsigned int hiMant;
  unsigned int loMant;

  if (num < 0)
  {
    sign = 0x8000;
    num *= -1;
  }
  else
  {
    sign = 0;
  }

  if (num == 0)
  {
    expon  = 0;
    hiMant = 0;
    loMant = 0;
  }
  else
  {
    fMant = frexp (num,&expon);
    if ((expon > 16384) || !(fMant < 1))
    {
      // Infinity or NaN
      expon  = sign|0x7FFF;
      hiMant = 0;
      loMant = 0; /* infinity */
    }
    else
    {
      // Finite
      expon += 16382;
      if (expon < 0)
      {
        // denormalized
        fMant = ldexp (fMant,expon);
        expon = 0;
      }
      expon |= sign;
      fMant = ldexp (fMant,32);          
      fsMant = floor (fMant); 
      hiMant = FloatToUnsigned (fsMant);
      fMant = ldexp (fMant-fsMant,32); 
      fsMant = floor (fMant); 
      loMant = FloatToUnsigned (fsMant);
    }
  }
    
  bytes[0] = expon >> 8;
  bytes[1] = expon;
  bytes[2] = hiMant >> 24;
  bytes[3] = hiMant >> 16;
  bytes[4] = hiMant >> 8;
  bytes[5] = hiMant;
  bytes[6] = loMant >> 24;
  bytes[7] = loMant >> 16;
  bytes[8] = loMant >> 8;
  bytes[9] = loMant;
}

/*---------------------------------------------------------------------------
| FUNCTION convertFromIeeeExtended
---------------------------------------------------------------------------*/
double convertFromIeeeExtended (unsigned char *bytes)
{
  int expon;
  double f;
  unsigned int hiMant;
  unsigned int loMant;
  
  expon = ((bytes[0] & 0x7F) << 8) | (bytes[1] & 0xFF);
  hiMant = ((unsigned int)(bytes[2] & 0xFF) << 24)
    | ((unsigned int)(bytes[3] & 0xFF) << 16)
    | ((unsigned int)(bytes[4] & 0xFF) << 8)
    | ((unsigned int)(bytes[5] & 0xFF));
    
  loMant = ((unsigned int)(bytes[6] & 0xFF) << 24)
    | ((unsigned int)(bytes[7] & 0xFF) << 16)
    | ((unsigned int)(bytes[8] & 0xFF) << 8)
    | ((unsigned int)(bytes[9] & 0xFF));

  if (expon == 0 && hiMant == 0 && loMant == 0)
  {
    f = 0;
  }
  else
  {
    if (expon == 0x7FFF)
    {
      // Infinity or NaN
      f = HUGE_VAL;
    }
    else
    {
      expon -= 16383;
      f = ldexp (UnsignedToFloat (hiMant),expon-=31);
      f += ldexp (UnsignedToFloat (loMant),expon-=32);
    }
  }

  if (bytes[0] & 0x80)
    return -f;
  else
    return f;
}

/***************************************************************************/