Ichthyostega
29ca3a485f
- decided to abstract the scheduler invocations as λ - so this functor contains the bare loop logic Investigation regarding hash-framework: It turns out that boost::hash uses a different hash_combine, than what we have extracted/duplicated in lib/hash-value.hpp (either this was a mistake, or boost::hash did use this weaker function at that time and supplied a dedicated 64bit implementation later) Anyway, should use boost::hash for the time being maybe also fix the duplicated impl in lib/hash-value.hpp
115 lines
3 KiB
C++
115 lines
3 KiB
C++
/*
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HASH-VALUE.hpp - collection of tools and definitions for working with hashes
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Copyright (C) Lumiera.org
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2012, Hermann Vosseler <Ichthyostega@web.de>
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License as
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published by the Free Software Foundation; either version 2 of
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the License, or (at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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*/
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/** @file hash-value.h
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** Hash value types and utilities.
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** This header defines the basic hash value types and provides some simple
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** utilities to support working with hash values.
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**
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** @see HashIndexed
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**
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*/
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#ifndef LIB_HASH_VALUE_H
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#define LIB_HASH_VALUE_H
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#include <stdlib.h>
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/**
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* storage for a Lumiera unique ID,
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* based on a 128bit random number
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*/
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typedef unsigned char lumiera_uid[16];
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typedef lumiera_uid* LumieraUid;
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#ifdef __cplusplus /* =========== C++ definitions ====================== */
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namespace lib {
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/** a STL compatible hash value */
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typedef size_t HashVal;
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/** a Lumiera UID */
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typedef lumiera_uid* LUID;
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namespace hash {
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/** meld the additional hash value into the given
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* base hash value. This is the standard formula
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* used by the STL and Boost to combine the
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* hash values of parts into a composite.
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*/
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inline void
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combine (size_t & combinedHash, size_t additionalHash)
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{
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combinedHash ^= additionalHash
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+ 0x9e3779b9
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+ (combinedHash<<6)
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+ (combinedHash>>2);
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}
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/////////////////////////////////////////////////////////////////////////////////////////////////////////TICKET #722 : Boost uses a stronger impl here on 64bit platforms
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/// see: Boost 1.67 <include>/boost/container_has/hash.hpp
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///
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/*
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// Don't define 64-bit hash combine on platforms without 64 bit integers,
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// and also not for 32-bit gcc as it warns about the 64-bit constant.
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#if !defined(BOOST_NO_INT64_T) && \
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!(defined(__GNUC__) && ULONG_MAX == 0xffffffff)
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inline void hash_combine_impl(boost::uint64_t& h,
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boost::uint64_t k)
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{
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const boost::uint64_t m = UINT64_C(0xc6a4a7935bd1e995);
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const int r = 47;
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k *= m;
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k ^= k >> r;
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k *= m;
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h ^= k;
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h *= m;
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// Completely arbitrary number, to prevent 0's
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// from hashing to 0.
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h += 0xe6546b64;
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}
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#endif // BOOST_NO_INT64_T
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*/
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//
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// WIP more utils to come here....
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}
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} // namespace lib
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#endif /* C++ */
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#endif /*LIB_HASH_UTIL_H*/
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