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[/] [openrisc/] [trunk/] [gnu-dev/] [or1k-gcc/] [libstdc++-v3/] [src/] [c++98/] [hash-long-double-tr1-aux.cc] - Rev 753
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// std::tr1::hash definitions, long double bits -*- C++ -*- // Copyright (C) 2010, 2011 Free Software Foundation, Inc. // // This file is part of the GNU ISO C++ Library. This library is free // software; you can redistribute it and/or modify it under the // terms of the GNU General Public License as published by the // Free Software Foundation; either version 3, or (at your option) // any later version. // This 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 General Public License for more details. // Under Section 7 of GPL version 3, you are granted additional // permissions described in the GCC Runtime Library Exception, version // 3.1, as published by the Free Software Foundation. // You should have received a copy of the GNU General Public License and // a copy of the GCC Runtime Library Exception along with this program; // see the files COPYING3 and COPYING.RUNTIME respectively. If not, see // <http://www.gnu.org/licenses/>. namespace std _GLIBCXX_VISIBILITY(default) { namespace tr1 { // For long double, careful with random padding bits (e.g., on x86, // 10 bytes -> 12 bytes) and resort to frexp. template<> size_t hash<long double>::operator()(long double __val) const { // 0 and -0 both hash to zero. if (__val == 0.0L) return 0; int __exponent; __val = __builtin_frexpl(__val, &__exponent); __val = __val < 0.0l ? -(__val + 0.5l) : __val; const long double __mult = __SIZE_MAX__ + 1.0l; __val *= __mult; // Try to use all the bits of the mantissa (really necessary only // on 32-bit targets, at least for 80-bit floating point formats). const size_t __hibits = (size_t)__val; __val = (__val - (long double)__hibits) * __mult; const size_t __coeff = __SIZE_MAX__ / __LDBL_MAX_EXP__; return __hibits + (size_t)__val + __coeff * __exponent; } } }
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