source:
vendors/XIOS/current/extern/boost/include/boost/functional/hash/detail/hash_float_x86.hpp
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3428
Last change on this file since 3428 was 3428, checked in by rblod, 12 years ago | |
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1 | |
2 | // Copyright 2005-2009 Daniel James. |
3 | // Distributed under the Boost Software License, Version 1.0. (See accompanying |
4 | // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt) |
5 | |
6 | // A non-portable hash function form non-zero floats on x86. |
7 | // |
8 | // Even if you're on an x86 platform, this might not work if their floating |
9 | // point isn't set up as this expects. So this should only be used if it's |
10 | // absolutely certain that it will work. |
11 | |
12 | #if !defined(BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_X86_HEADER) |
13 | #define BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_X86_HEADER |
14 | |
15 | #include <boost/cstdint.hpp> |
16 | |
17 | #if defined(_MSC_VER) && (_MSC_VER >= 1020) |
18 | # pragma once |
19 | #endif |
20 | |
21 | namespace boost |
22 | { |
23 | namespace hash_detail |
24 | { |
25 | inline void hash_float_combine(std::size_t& seed, std::size_t value) |
26 | { |
27 | seed ^= value + (seed<<6) + (seed>>2); |
28 | } |
29 | |
30 | inline std::size_t float_hash_impl(float v) |
31 | { |
32 | boost::uint32_t* ptr = (boost::uint32_t*)&v; |
33 | std::size_t seed = *ptr; |
34 | return seed; |
35 | } |
36 | |
37 | inline std::size_t float_hash_impl(double v) |
38 | { |
39 | boost::uint32_t* ptr = (boost::uint32_t*)&v; |
40 | std::size_t seed = *ptr++; |
41 | hash_float_combine(seed, *ptr); |
42 | return seed; |
43 | } |
44 | |
45 | inline std::size_t float_hash_impl(long double v) |
46 | { |
47 | boost::uint32_t* ptr = (boost::uint32_t*)&v; |
48 | std::size_t seed = *ptr++; |
49 | hash_float_combine(seed, *ptr++); |
50 | hash_float_combine(seed, *(boost::uint16_t*)ptr); |
51 | return seed; |
52 | } |
53 | } |
54 | } |
55 | |
56 | #endif |
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