platform/gp2x/uClibc/math_private.h

   1 /*
   2  * ====================================================
   3  * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
   4  *
   5  * Developed at SunPro, a Sun Microsystems, Inc. business.
   6  * Permission to use, copy, modify, and distribute this
   7  * software is freely granted, provided that this notice
   8  * is preserved.
   9  * ====================================================
  10  */
  11
  12 /*
  13  * from: @(#)fdlibm.h 5.1 93/09/24
  14  * $Id: math_private.h,v 1.3 2004/02/09 07:10:38 andersen Exp $
  15  */
  16
  17 #ifndef _MATH_PRIVATE_H_
  18 #define _MATH_PRIVATE_H_
  19
  20 #include <endian.h>
  21 #include <sys/types.h>
  22
  23 /* The original fdlibm code used statements like:
  24         n0 = ((*(int*)&one)>>29)^1;             * index of high word *
  25         ix0 = *(n0+(int*)&x);                   * high word of x *
  26         ix1 = *((1-n0)+(int*)&x);               * low word of x *
  27    to dig two 32 bit words out of the 64 bit IEEE floating point
  28    value.  That is non-ANSI, and, moreover, the gcc instruction
  29    scheduler gets it wrong.  We instead use the following macros.
  30    Unlike the original code, we determine the endianness at compile
  31    time, not at run time; I don't see much benefit to selecting
  32    endianness at run time.  */
  33
  34 /* A union which permits us to convert between a double and two 32 bit
  35    ints.  */
  36
  37 /*
  38  * Math on arm is special:
  39  * For FPA, float words are always big-endian.
  40  * For VFP, floats words follow the memory system mode.
  41  */
  42
  43 #if (__BYTE_ORDER == __BIG_ENDIAN) || \
  44     (!defined(__VFP_FP__) && (defined(__arm__) || defined(__thumb__)))
  45
  46 typedef union
  47 {
  48   double value;
  49   struct
  50   {
  51     u_int32_t msw;
  52     u_int32_t lsw;
  53   } parts;
  54 } ieee_double_shape_type;
  55
  56 #else
  57
  58 typedef union
  59 {
  60   double value;
  61   struct
  62   {
  63     u_int32_t lsw;
  64     u_int32_t msw;
  65   } parts;
  66 } ieee_double_shape_type;
  67
  68 #endif
  69
  70 /* Get two 32 bit ints from a double.  */
  71
  72 #define EXTRACT_WORDS(ix0,ix1,d)                                \
  73 do {                                                            \
  74   ieee_double_shape_type ew_u;                                  \
  75   ew_u.value = (d);                                             \
  76   (ix0) = ew_u.parts.msw;                                       \
  77   (ix1) = ew_u.parts.lsw;                                       \
  78 } while (0)
  79
  80 /* Get the more significant 32 bit int from a double.  */
  81
  82 #define GET_HIGH_WORD(i,d)                                      \
  83 do {                                                            \
  84   ieee_double_shape_type gh_u;                                  \
  85   gh_u.value = (d);                                             \
  86   (i) = gh_u.parts.msw;                                         \
  87 } while (0)
  88
  89 /* Get the less significant 32 bit int from a double.  */
  90
  91 #define GET_LOW_WORD(i,d)                                       \
  92 do {                                                            \
  93   ieee_double_shape_type gl_u;                                  \
  94   gl_u.value = (d);                                             \
  95   (i) = gl_u.parts.lsw;                                         \
  96 } while (0)
  97
  98 /* Set a double from two 32 bit ints.  */
  99
 100 #define INSERT_WORDS(d,ix0,ix1)                                 \
 101 do {                                                            \
 102   ieee_double_shape_type iw_u;                                  \
 103   iw_u.parts.msw = (ix0);                                       \
 104   iw_u.parts.lsw = (ix1);                                       \
 105   (d) = iw_u.value;                                             \
 106 } while (0)
 107
 108 /* Set the more significant 32 bits of a double from an int.  */
 109
 110 #define SET_HIGH_WORD(d,v)                                      \
 111 do {                                                            \
 112   ieee_double_shape_type sh_u;                                  \
 113   sh_u.value = (d);                                             \
 114   sh_u.parts.msw = (v);                                         \
 115   (d) = sh_u.value;                                             \
 116 } while (0)
 117
 118 /* Set the less significant 32 bits of a double from an int.  */
 119
 120 #define SET_LOW_WORD(d,v)                                       \
 121 do {                                                            \
 122   ieee_double_shape_type sl_u;                                  \
 123   sl_u.value = (d);                                             \
 124   sl_u.parts.lsw = (v);                                         \
 125   (d) = sl_u.value;                                             \
 126 } while (0)
 127
 128
 129 #endif /* _MATH_PRIVATE_H_ */