forked from boostorg/functional
Daniel James
1c701a70bb
in hash and seperate out some of the detail headers. Merged revisions 53159-53161,53167-53169,53175,53185,53205,53247-53248,53254 via svnmerge from https://svn.boost.org/svn/boost/trunk ........ r53159 | danieljames | 2009-05-21 22:21:11 +0100 (Thu, 21 May 2009) | 1 line Move the hash limits workaround into its own file. ........ r53160 | danieljames | 2009-05-21 22:21:44 +0100 (Thu, 21 May 2009) | 1 line Move the two different hash float implementation into their own header. ........ r53161 | danieljames | 2009-05-21 22:22:04 +0100 (Thu, 21 May 2009) | 1 line Try to automatically detect which float functions are available. ........ r53167 | danieljames | 2009-05-22 07:00:56 +0100 (Fri, 22 May 2009) | 1 line Fix a typo. ........ r53168 | danieljames | 2009-05-22 07:01:19 +0100 (Fri, 22 May 2009) | 3 lines Spell out exactly which functions can be used with which types. I was hitting some ambiguity errors when the function was for the wrong type. ........ r53169 | danieljames | 2009-05-22 07:01:35 +0100 (Fri, 22 May 2009) | 1 line Some STLport fixes for hash. ........ r53175 | danieljames | 2009-05-22 14:35:56 +0100 (Fri, 22 May 2009) | 2 lines Rename struct to avoid using 'type::'type' which confuses some compilers. ........ r53185 | danieljames | 2009-05-22 20:00:35 +0100 (Fri, 22 May 2009) | 1 line Explicitly qualify 'none' to avoid confusion with boost::none. ........ r53205 | danieljames | 2009-05-23 16:21:38 +0100 (Sat, 23 May 2009) | 4 lines Try to deal with macros for frexpl and ldexpl. The error message for msvc-9.0~wm5~stlport5.2 suggests that frexpl and ldexpl are macros. ........ r53247 | danieljames | 2009-05-25 14:45:16 +0100 (Mon, 25 May 2009) | 4 lines Check for float functions with less templates. The only template mechanism now used is full specialization, so this should hopefully be more portable to compilers we don't test. ........ r53248 | danieljames | 2009-05-25 15:27:00 +0100 (Mon, 25 May 2009) | 1 line Fix a couple of clumsy errors in the last commit. ........ r53254 | danieljames | 2009-05-25 20:44:52 +0100 (Mon, 25 May 2009) | 1 line Hash change log. ........ [SVN r53361]
57 lines
1.6 KiB
C++
57 lines
1.6 KiB
C++
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// Copyright 2005-2009 Daniel James.
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// Distributed under the Boost Software License, Version 1.0. (See accompanying
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// file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
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// A non-portable hash function form non-zero floats on x86.
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//
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// Even if you're on an x86 platform, this might not work if their floating
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// point isn't set up as this expects. So this should only be used if it's
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// absolutely certain that it will work.
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#if !defined(BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_X86_HEADER)
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#define BOOST_FUNCTIONAL_HASH_DETAIL_HASH_FLOAT_X86_HEADER
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#include <boost/cstdint.hpp>
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#if defined(_MSC_VER) && (_MSC_VER >= 1020)
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# pragma once
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#endif
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namespace boost
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{
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namespace hash_detail
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{
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inline void hash_float_combine(std::size_t& seed, std::size_t value)
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{
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seed ^= value + (seed<<6) + (seed>>2);
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}
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inline std::size_t float_hash_impl(float v)
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{
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boost::uint32_t* ptr = (boost::uint32_t*)&v;
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std::size_t seed = *ptr;
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return seed;
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}
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inline std::size_t float_hash_impl(double v)
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{
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boost::uint32_t* ptr = (boost::uint32_t*)&v;
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std::size_t seed = *ptr++;
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hash_float_combine(seed, *ptr);
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return seed;
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}
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inline std::size_t float_hash_impl(long double v)
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{
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boost::uint32_t* ptr = (boost::uint32_t*)&v;
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std::size_t seed = *ptr++;
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hash_float_combine(seed, *ptr++);
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hash_float_combine(seed, *(boost::uint16_t*)ptr);
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return seed;
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}
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}
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}
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#endif
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