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Added simple integer and pointer hashes

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This commit is contained in:
Danny Robson 2011-10-26 23:45:01 +11:00
parent 2cf895daf9
commit 796a3d3639
3 changed files with 84 additions and 0 deletions
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2
Makefile.am
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@ -29,6 +29,8 @@ UTIL_FILES = \
fwd.hpp \
guid.cpp \
guid.hpp \
hash.cpp \
hash.hpp \
io.cpp \
io.hpp \
ip.cpp \

53
hash.cpp Normal file
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@ -0,0 +1,53 @@
/*
* This file is part of libgim.
*
* Waif 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 of the License, or (at your option) any later
* version.
*
* Waif 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.
*
* You should have received a copy of the GNU General Public License
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2010 Danny Robson <danny@blubinc.net>
*/
#include "hash.hpp"
// Thomas Wang's 32 bit mixing function
uint32_t
hash (uint32_t key) {
uint32_t c2 = 0x27d4eb2d; // a prime or an odd constant
key = (key ^ 61) ^ (key >> 16);
key = key + (key << 3);
key = key ^ (key >> 4);
key = key * c2;
key = key ^ (key >> 15);
return key;
}
// Thomas Wang's 64 bit mixing function
uint64_t
hash (uint64_t key) {
key = (~key) + (key << 21); // key = (key << 21) - key - 1;
key = key ^ (key >> 24);
key = (key + (key << 3)) + (key << 8); // key * 265
key = key ^ (key >> 14);
key = (key + (key << 2)) + (key << 4); // key * 21
key = key ^ (key >> 28);
key = key + (key << 31);
return key;
}
uintptr_t
hash (void *const key)
{ return hash ((uintptr_t)key); }

29
hash.hpp Normal file
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@ -0,0 +1,29 @@
/*
* This file is part of libgim.
*
* Waif 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 of the License, or (at your option) any later
* version.
*
* Waif 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.
*
* You should have received a copy of the GNU General Public License
* along with libgim. If not, see <http://www.gnu.org/licenses/>.
*
* Copyright 2010 Danny Robson <danny@blubinc.net>
*/
#ifndef __UTIL_HASH_HPP
#define __UTIL_HASH_HPP
#include <cstdint>
uint32_t hash (uint32_t key);
uint64_t hash (uint64_t key);
uintptr_t hash (void * const);
#endif