1 /* auxiliary data to generate special IEEE floats (NaN, +Inf, -Inf) 2 3 Copyright 1999-2023 Free Software Foundation, Inc. 4 Contributed by the AriC and Caramba 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 https://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 _MPFR_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 44 45 /* For NaN, we use DBL_NAN since the memory representation of a NaN depends 46 on the processor: a fixed memory representation could yield either a 47 quiet NaN (qNaN) or a signaling NaN (sNaN). For instance, HP PA-RISC 48 is known to do the opposite way of the usual choice recommended in 49 IEEE 754-2008; see: 50 https://grouper.ieee.org/groups/1788/email/msg03272.html 51 52 Moreover, the right choice is to generate a qNaN in particular because 53 signaling NaNs are not supported by all compilers (note that the support 54 must be in the compiler used to build the user-end application because 55 this is where the sNaN will be obtained). */ 56 57 #ifdef HAVE_DOUBLE_IEEE_LITTLE_ENDIAN 58 static const union dbl_bytes dbl_infp = 59 { { 0, 0, 0, 0, 0, 0, 0xF0, 0x7F } }; 60 static const union dbl_bytes dbl_infm = 61 { { 0, 0, 0, 0, 0, 0, 0xF0, 0xFF } }; 62 #endif 63 64 #ifdef HAVE_DOUBLE_IEEE_BIG_ENDIAN 65 static const union dbl_bytes dbl_infp = 66 { { 0x7F, 0xF0, 0, 0, 0, 0, 0, 0 } }; 67 static const union dbl_bytes dbl_infm = 68 { { 0xFF, 0xF0, 0, 0, 0, 0, 0, 0 } }; 69 #endif 70 71 #else /* _MPFR_IEEE_FLOATS */ 72 73 #define MPFR_DBL_INFP DBL_POS_INF 74 #define MPFR_DBL_INFM DBL_NEG_INF 75 #define MPFR_DBL_NAN DBL_NAN 76 77 #endif /* _MPFR_IEEE_FLOATS */ 78