source/libs/mpfr/mpfr-3.1.3/src/ieee_floats.h

   1 /* auxiliary data to generate special IEEE floats (NaN, +Inf, -Inf)
   2
   3 Copyright 1999-2015 Free Software Foundation, Inc.
   4 Contributed by the AriC and Caramel projects, INRIA.
   5
   6 This file is part of the GNU MPFR Library.
   7
   8 The GNU MPFR Library is free software; you can redistribute it and/or modify
   9 it under the terms of the GNU Lesser General Public License as published by
  10 the Free Software Foundation; either version 3 of the License, or (at your
  11 option) any later version.
  12
  13 The GNU MPFR Library is distributed in the hope that it will be useful, but
  14 WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
  15 or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
  16 License for more details.
  17
  18 You should have received a copy of the GNU Lesser General Public License
  19 along with the GNU MPFR Library; see the file COPYING.LESSER.  If not, see
  20 http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
  21 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
  22
  23 /* "double" NaN and infinities are written as explicit bytes to be sure of
  24    getting what we want, and to be sure of not depending on libm.
  25
  26    Could use 4-byte "float" values and let the code convert them, but it
  27    seems more direct to give exactly what we want.  Certainly for gcc 3.0.2
  28    on alphaev56-unknown-freebsd4.3 the NaN must be 8-bytes, since that
  29    compiler+system was seen incorrectly converting from a "float" NaN.  */
  30
  31 #if _GMP_IEEE_FLOATS
  32
  33 /* The "d" field guarantees alignment to a suitable boundary for a double.
  34    Could use a union instead, if we checked the compiler supports union
  35    initializers.  */
  36 union dbl_bytes {
  37   unsigned char b[8];
  38   double d;
  39 };
  40
  41 #define MPFR_DBL_INFP  (dbl_infp.d)
  42 #define MPFR_DBL_INFM  (dbl_infm.d)
  43 #define MPFR_DBL_NAN   (dbl_nan.d)
  44
  45 /* Warning! dbl_nan.d is not consistently the same NaN on all the
  46    processors: it can be either a qNaN (quiet) or sNaN (signaling).
  47    Processors are known to differ... */
  48
  49 #if HAVE_DOUBLE_IEEE_LITTLE_ENDIAN
  50 static const union dbl_bytes dbl_infp =
  51   { { 0, 0, 0, 0, 0, 0, 0xF0, 0x7F } };
  52 static const union dbl_bytes dbl_infm =
  53   { { 0, 0, 0, 0, 0, 0, 0xF0, 0xFF } };
  54 static const union dbl_bytes dbl_nan  =
  55   { { 0, 0, 0, 0, 0, 0, 0xF8, 0x7F } };
  56 #endif
  57 #if HAVE_DOUBLE_IEEE_LITTLE_SWAPPED
  58 static const union dbl_bytes dbl_infp =
  59   { { 0, 0, 0xF0, 0x7F, 0, 0, 0, 0 } };
  60 static const union dbl_bytes dbl_infm =
  61   { { 0, 0, 0xF0, 0xFF, 0, 0, 0, 0 } };
  62 static const union dbl_bytes dbl_nan  =
  63   { { 0, 0, 0xF8, 0x7F, 0, 0, 0, 0 } };
  64 #endif
  65 #if HAVE_DOUBLE_IEEE_BIG_ENDIAN
  66 static const union dbl_bytes dbl_infp =
  67   { { 0x7F, 0xF0, 0, 0, 0, 0, 0, 0 } };
  68 static const union dbl_bytes dbl_infm =
  69   { { 0xFF, 0xF0, 0, 0, 0, 0, 0, 0 } };
  70 static const union dbl_bytes dbl_nan  =
  71   { { 0x7F, 0xF8, 0, 0, 0, 0, 0, 0 } };
  72 #endif
  73
  74 #else /* _GMP_IEEE_FLOATS */
  75
  76 #define MPFR_DBL_INFP DBL_POS_INF
  77 #define MPFR_DBL_INFM DBL_NEG_INF
  78 #define MPFR_DBL_NAN DBL_NAN
  79
  80 #endif /* _GMP_IEEE_FLOATS */