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/* auxiliary data to generate special IEEE floats (NaN, +Inf, -Inf)
Copyright 1999-2017 Free Software Foundation, Inc.
Contributed by the AriC and Caramba projects, INRIA.
This file is part of the GNU MPFR Library.
The GNU MPFR Library is free software; you can redistribute it and/or modify
it under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 3 of the License, or (at your
option) any later version.
The GNU MPFR Library is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
License for more details.
You should have received a copy of the GNU Lesser General Public License
along with the GNU MPFR Library; see the file COPYING.LESSER. If not, see
http://www.gnu.org/licenses/ or write to the Free Software Foundation, Inc.,
51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA. */
/* "double" NaN and infinities are written as explicit bytes to be sure of
getting what we want, and to be sure of not depending on libm.
Could use 4-byte "float" values and let the code convert them, but it
seems more direct to give exactly what we want. Certainly for gcc 3.0.2
on alphaev56-unknown-freebsd4.3 the NaN must be 8-bytes, since that
compiler+system was seen incorrectly converting from a "float" NaN. */
#if _MPFR_IEEE_FLOATS
/* The "d" field guarantees alignment to a suitable boundary for a double.
Could use a union instead, if we checked the compiler supports union
initializers. */
union dbl_bytes {
unsigned char b[8];
double d;
};
#define MPFR_DBL_INFP (dbl_infp.d)
#define MPFR_DBL_INFM (dbl_infm.d)
#define MPFR_DBL_NAN DBL_NAN
/* For NaN, we use DBL_NAN since the memory representation of a NaN depends
on the processor: a fixed memory representation could yield either a
quiet NaN (qNaN) or a signaling NaN (sNaN). For instance, HP PA-RISC
is known to do the opposite way of the usual choice recommended in
IEEE 754-2008; see:
http://grouper.ieee.org/groups/1788/email/msg03272.html
Moreover, the right choice is to generate a qNaN in particular because
signaling NaNs are not supported by all compilers (note that the support
must be in the compiler used to build the user-end application because
this is where the sNaN will be obtained). */
#ifdef HAVE_DOUBLE_IEEE_LITTLE_ENDIAN
static const union dbl_bytes dbl_infp =
{ { 0, 0, 0, 0, 0, 0, 0xF0, 0x7F } };
static const union dbl_bytes dbl_infm =
{ { 0, 0, 0, 0, 0, 0, 0xF0, 0xFF } };
#endif
#ifdef HAVE_DOUBLE_IEEE_BIG_ENDIAN
static const union dbl_bytes dbl_infp =
{ { 0x7F, 0xF0, 0, 0, 0, 0, 0, 0 } };
static const union dbl_bytes dbl_infm =
{ { 0xFF, 0xF0, 0, 0, 0, 0, 0, 0 } };
#endif
#else /* _MPFR_IEEE_FLOATS */
#define MPFR_DBL_INFP DBL_POS_INF
#define MPFR_DBL_INFM DBL_NEG_INF
#define MPFR_DBL_NAN DBL_NAN
#endif /* _MPFR_IEEE_FLOATS */
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