diff options
Diffstat (limited to 'gcc-4.6/libstdc++-v3/src/hash_c++0x.cc')
| -rw-r--r-- | gcc-4.6/libstdc++-v3/src/hash_c++0x.cc | 26 |
1 files changed, 24 insertions, 2 deletions
diff --git a/gcc-4.6/libstdc++-v3/src/hash_c++0x.cc b/gcc-4.6/libstdc++-v3/src/hash_c++0x.cc index 852498d..d685074 100644 --- a/gcc-4.6/libstdc++-v3/src/hash_c++0x.cc +++ b/gcc-4.6/libstdc++-v3/src/hash_c++0x.cc @@ -1,6 +1,6 @@ // std::hash definitions -*- C++ -*- -// Copyright (C) 2010 Free Software Foundation, Inc. +// 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 @@ -30,5 +30,27 @@ namespace std _GLIBCXX_VISIBILITY(default) { -#include "hash-long-double-aux.cc" + _GLIBCXX_PURE size_t + hash<long double>::operator()(long double __val) const noexcept + { + // 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; + } } |