kolibrios/programs/media/ac97snd/trunk/mp3dec/math_private.h

/*
 * ====================================================
 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
 *
 * Developed at SunPro, a Sun Microsystems, Inc. business.
 * Permission to use, copy, modify, and distribute this
 * software is freely granted, provided that this notice
 * is preserved.
 * ====================================================
 */

/*
 * from: @(#)fdlibm.h 5.1 93/09/24
 * $Id: math_private.h,v 1.8 1998/11/27 11:33:46 drepper Exp $
 */

#ifndef _MATH_PRIVATE_H_
#define _MATH_PRIVATE_H_


/* The original fdlibm code used statements like:
	n0 = ((*(int*)&one)>>29)^1;		* index of high word *
	ix0 = *(n0+(int*)&x);			* high word of x *
	ix1 = *((1-n0)+(int*)&x);		* low word of x *
   to dig two 32 bit words out of the 64 bit IEEE floating point
   value.  That is non-ANSI, and, moreover, the gcc instruction
   scheduler gets it wrong.  We instead use the following macros.
   Unlike the original code, we determine the endianness at compile
   time, not at run time; I don't see much benefit to selecting
   endianness at run time.  */

/* A union which permits us to convert between a double and two 32 bit
   ints.  */

typedef int int32_t; 
typedef unsigned int u_int32_t;

typedef union
{
  double value;
  struct
  {
    u_int32_t lsw;
    u_int32_t msw;
  } parts;
} ieee_double_shape_type;

/* Get two 32 bit ints from a double.  */

#define EXTRACT_WORDS(ix0,ix1,d)				\
do {								\
  ieee_double_shape_type ew_u;					\
  ew_u.value = (d);						\
  (ix0) = ew_u.parts.msw;					\
  (ix1) = ew_u.parts.lsw;					\
} while (0)

/* Get the more significant 32 bit int from a double.  */

#define GET_HIGH_WORD(i,d)					\
do {								\
  ieee_double_shape_type gh_u;					\
  gh_u.value = (d);						\
  (i) = gh_u.parts.msw;						\
} while (0)

/* Get the less significant 32 bit int from a double.  */

#define GET_LOW_WORD(i,d)					\
do {								\
  ieee_double_shape_type gl_u;					\
  gl_u.value = (d);						\
  (i) = gl_u.parts.lsw;						\
} while (0)

/* Set a double from two 32 bit ints.  */

#define INSERT_WORDS(d,ix0,ix1)					\
do {								\
  ieee_double_shape_type iw_u;					\
  iw_u.parts.msw = (ix0);					\
  iw_u.parts.lsw = (ix1);					\
  (d) = iw_u.value;						\
} while (0)

/* Set the more significant 32 bits of a double from an int.  */

#define SET_HIGH_WORD(d,v)					\
do {								\
  ieee_double_shape_type sh_u;					\
  sh_u.value = (d);						\
  sh_u.parts.msw = (v);						\
  (d) = sh_u.value;						\
} while (0)

/* Set the less significant 32 bits of a double from an int.  */

#define SET_LOW_WORD(d,v)					\
do {								\
  ieee_double_shape_type sl_u;					\
  sl_u.value = (d);						\
  sl_u.parts.lsw = (v);						\
  (d) = sl_u.value;						\
} while (0)

/* A union which permits us to convert between a float and a 32 bit
   int.  */

typedef union
{
  float value;
  u_int32_t word;
} ieee_float_shape_type;

/* Get a 32 bit int from a float.  */

#define GET_FLOAT_WORD(i,d)					\
do {								\
  ieee_float_shape_type gf_u;					\
  gf_u.value = (d);						\
  (i) = gf_u.word;						\
} while (0)

/* Set a float from a 32 bit int.  */

#define SET_FLOAT_WORD(d,i)					\
do {								\
  ieee_float_shape_type sf_u;					\
  sf_u.word = (i);						\
  (d) = sf_u.value;						\
} while (0)

/* A union which permits us to convert between a long double and
   three 32 bit ints.  */


typedef union
{
  long double value;
  struct
  {
    u_int32_t lsw;
    u_int32_t msw;
    unsigned int sign_exponent:16;
    unsigned int empty:16;
  } parts;
} ieee_long_double_shape_type;

/* Get three 32 bit ints from a double.  */

#define GET_LDOUBLE_WORDS(exp,ix0,ix1,d)			\
do {								\
  ieee_long_double_shape_type ew_u;				\
  ew_u.value = (d);						\
  (exp) = ew_u.parts.sign_exponent;				\
  (ix0) = ew_u.parts.msw;					\
  (ix1) = ew_u.parts.lsw;					\
} while (0)

/* Set a double from two 32 bit ints.  */

#define SET_LDOUBLE_WORDS(d,exp,ix0,ix1)			\
do {								\
  ieee_long_double_shape_type iw_u;				\
  iw_u.parts.sign_exponent = (exp);				\
  iw_u.parts.msw = (ix0);					\
  iw_u.parts.lsw = (ix1);					\
  (d) = iw_u.value;						\
} while (0)

/* Get the more significant 32 bits of a long double mantissa.  */

#define GET_LDOUBLE_MSW(v,d)					\
do {								\
  ieee_long_double_shape_type sh_u;				\
  sh_u.value = (d);						\
  (v) = sh_u.parts.msw;						\
} while (0)

/* Set the more significant 32 bits of a long double mantissa from an int.  */

#define SET_LDOUBLE_MSW(d,v)					\
do {								\
  ieee_long_double_shape_type sh_u;				\
  sh_u.value = (d);						\
  sh_u.parts.msw = (v);						\
  (d) = sh_u.value;						\
} while (0)

/* Get int from the exponent of a long double.  */

#define GET_LDOUBLE_EXP(exp,d)					\
do {								\
  ieee_long_double_shape_type ge_u;				\
  ge_u.value = (d);						\
  (exp) = ge_u.parts.sign_exponent;				\
} while (0)

/* Set exponent of a long double from an int.  */

#define SET_LDOUBLE_EXP(d,exp)					\
do {								\
  ieee_long_double_shape_type se_u;				\
  se_u.value = (d);						\
  se_u.parts.sign_exponent = (exp);				\
  (d) = se_u.value;						\
} while (0)

#endif /* _MATH_PRIVATE_H_ */