mirror of
https://github.com/UberGames/GtkRadiant.git
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d584d94549
git-svn-id: svn://svn.icculus.org/gtkradiant/GtkRadiant/trunk@26 8a3a26a2-13c4-0310-b231-cf6edde360e5
434 lines
12 KiB
C++
434 lines
12 KiB
C++
/*
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Copyright (C) 2001-2006, William Joseph.
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All Rights Reserved.
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This file is part of GtkRadiant.
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GtkRadiant is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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GtkRadiant 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 GtkRadiant; if not, write to the Free Software
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Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#if !defined(INCLUDED_CONTAINER_HASHFUNC_H)
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#define INCLUDED_CONTAINER_HASHFUNC_H
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#include <cctype>
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#include "string/string.h"
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#include "container/array.h"
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typedef unsigned long int ub4; /* unsigned 4-byte quantities */
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typedef unsigned char ub1;
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inline ub1 ub1_as_ub1_nocase(ub1 byte)
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{
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return std::tolower(byte);
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}
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inline ub4 ub1x4_as_ub4_nocase(const ub1 bytes[4])
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{
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ub4 result;
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reinterpret_cast<ub1*>(&result)[0] = ub1_as_ub1_nocase(bytes[0]);
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reinterpret_cast<ub1*>(&result)[1] = ub1_as_ub1_nocase(bytes[1]);
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reinterpret_cast<ub1*>(&result)[2] = ub1_as_ub1_nocase(bytes[2]);
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reinterpret_cast<ub1*>(&result)[3] = ub1_as_ub1_nocase(bytes[3]);
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return result;
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}
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class ub1_default_traits
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{
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public:
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static ub1 as_ub1(ub1 byte)
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{
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return byte;
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}
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};
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class ub1_nocase_traits
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{
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public:
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static ub1 as_ub1(ub1 byte)
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{
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return ub1_as_ub1_nocase(byte);
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}
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};
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class ub1x4_default_traits
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{
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public:
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static ub4 as_ub4(const ub1 bytes[4])
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{
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return *reinterpret_cast<const ub4*>(bytes);
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}
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};
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class ub1x4_nocase_traits
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{
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public:
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static ub4 as_ub4(const ub1 bytes[4])
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{
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return ub1x4_as_ub4_nocase(bytes);
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}
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};
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class ub4_default_traits
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{
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public:
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static ub4 as_ub4(ub4 i)
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{
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return i;
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}
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};
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class ub4_nocase_traits
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{
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public:
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static ub4 as_ub4(ub4 i)
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{
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return ub1x4_as_ub4_nocase(reinterpret_cast<const ub1*>(&i));
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}
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};
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// lookup2.c
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// By Bob Jenkins, 1996. bob_jenkins@burtleburtle.net. You may use this
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// code any way you wish, private, educational, or commercial. It's free.
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#define hashsize(n) ((ub4)1<<(n))
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#define hashmask(n) (hashsize(n)-1)
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/*
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--------------------------------------------------------------------
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mix -- mix 3 32-bit values reversibly.
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For every delta with one or two bit set, and the deltas of all three
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high bits or all three low bits, whether the original value of a,b,c
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is almost all zero or is uniformly distributed,
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* If mix() is run forward or backward, at least 32 bits in a,b,c
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have at least 1/4 probability of changing.
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* If mix() is run forward, every bit of c will change between 1/3 and
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2/3 of the time. (Well, 22/100 and 78/100 for some 2-bit deltas.)
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mix() was built out of 36 single-cycle latency instructions in a
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structure that could supported 2x parallelism, like so:
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a -= b;
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a -= c; x = (c>>13);
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b -= c; a ^= x;
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b -= a; x = (a<<8);
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c -= a; b ^= x;
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c -= b; x = (b>>13);
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...
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Unfortunately, superscalar Pentiums and Sparcs can't take advantage
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of that parallelism. They've also turned some of those single-cycle
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latency instructions into multi-cycle latency instructions. Still,
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this is the fastest good hash I could find. There were about 2^^68
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to choose from. I only looked at a billion or so.
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--------------------------------------------------------------------
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*/
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#define mix(a,b,c) \
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{ \
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a -= b; a -= c; a ^= (c>>13); \
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b -= c; b -= a; b ^= (a<<8); \
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c -= a; c -= b; c ^= (b>>13); \
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a -= b; a -= c; a ^= (c>>12); \
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b -= c; b -= a; b ^= (a<<16); \
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c -= a; c -= b; c ^= (b>>5); \
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a -= b; a -= c; a ^= (c>>3); \
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b -= c; b -= a; b ^= (a<<10); \
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c -= a; c -= b; c ^= (b>>15); \
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}
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/* same, but slower, works on systems that might have 8 byte ub4's */
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#define mix2(a,b,c) \
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{ \
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a -= b; a -= c; a ^= (c>>13); \
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b -= c; b -= a; b ^= (a<< 8); \
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c -= a; c -= b; c ^= ((b&0xffffffff)>>13); \
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a -= b; a -= c; a ^= ((c&0xffffffff)>>12); \
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b -= c; b -= a; b = (b ^ (a<<16)) & 0xffffffff; \
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c -= a; c -= b; c = (c ^ (b>> 5)) & 0xffffffff; \
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a -= b; a -= c; a = (a ^ (c>> 3)) & 0xffffffff; \
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b -= c; b -= a; b = (b ^ (a<<10)) & 0xffffffff; \
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c -= a; c -= b; c = (c ^ (b>>15)) & 0xffffffff; \
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}
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/*
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--------------------------------------------------------------------
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hash() -- hash a variable-length key into a 32-bit value
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k : the key (the unaligned variable-length array of bytes)
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len : the length of the key, counting by bytes
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level : can be any 4-byte value
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Returns a 32-bit value. Every bit of the key affects every bit of
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the return value. Every 1-bit and 2-bit delta achieves avalanche.
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About 36+6len instructions.
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The best hash table sizes are powers of 2. There is no need to do
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mod a prime (mod is sooo slow!). If you need less than 32 bits,
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use a bitmask. For example, if you need only 10 bits, do
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h = (h & hashmask(10));
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In which case, the hash table should have hashsize(10) elements.
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If you are hashing n strings (ub1 **)k, do it like this:
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for (i=0, h=0; i<n; ++i) h = hash( k[i], len[i], h);
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See http://burlteburtle.net/bob/hash/evahash.html
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Use for hash table lookup, or anything where one collision in 2^32 is
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acceptable. Do NOT use for cryptographic purposes.
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--------------------------------------------------------------------
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*/
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template<typename UB1Traits, typename UB4x1Traits>
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inline ub4 hash(
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const ub1 *k, /* the key */
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ub4 length, /* the length of the key */
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ub4 initval, /* the previous hash, or an arbitrary value */
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const UB1Traits& ub1traits,
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const UB4x1Traits& ub4x1traits
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)
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{
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register ub4 a,b,c,len;
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/* Set up the internal state */
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len = length;
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a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
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c = initval; /* the previous hash value */
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/*---------------------------------------- handle most of the key */
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while (len >= 12)
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{
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a += (k[0] +((ub4)UB1Traits::as_ub1(k[1])<<8) +((ub4)UB1Traits::as_ub1(k[2])<<16) +((ub4)UB1Traits::as_ub1(k[3])<<24));
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b += (k[4] +((ub4)UB1Traits::as_ub1(k[5])<<8) +((ub4)UB1Traits::as_ub1(k[6])<<16) +((ub4)UB1Traits::as_ub1(k[7])<<24));
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c += (k[8] +((ub4)UB1Traits::as_ub1(k[9])<<8) +((ub4)UB1Traits::as_ub1(k[10])<<16)+((ub4)UB1Traits::as_ub1(k[11])<<24));
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mix(a,b,c);
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k += 12; len -= 12;
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}
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/*------------------------------------- handle the last 11 bytes */
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c += length;
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switch(len) /* all the case statements fall through */
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{
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case 11: c += ((ub4)UB1Traits::as_ub1(k[10]) << 24);
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case 10: c += ((ub4)UB1Traits::as_ub1(k[9]) << 16);
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case 9 : c += ((ub4)UB1Traits::as_ub1(k[8]) << 8);
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/* the first byte of c is reserved for the length */
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case 8 : b += ((ub4)UB1Traits::as_ub1(k[7]) << 24);
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case 7 : b += ((ub4)UB1Traits::as_ub1(k[6]) << 16);
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case 6 : b += ((ub4)UB1Traits::as_ub1(k[5]) << 8);
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case 5 : b += UB1Traits::as_ub1(k[4]);
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case 4 : a += ((ub4)UB1Traits::as_ub1(k[3]) << 24);
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case 3 : a += ((ub4)UB1Traits::as_ub1(k[2]) << 16);
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case 2 : a += ((ub4)UB1Traits::as_ub1(k[1]) << 8);
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case 1 : a += UB1Traits::as_ub1(k[0]);
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/* case 0: nothing left to add */
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}
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mix(a,b,c);
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/*-------------------------------------------- report the result */
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return c;
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}
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/*
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--------------------------------------------------------------------
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This works on all machines. hash2() is identical to hash() on
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little-endian machines, except that the length has to be measured
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in ub4s instead of bytes. It is much faster than hash(). It
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requires
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-- that the key be an array of ub4's, and
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-- that all your machines have the same endianness, and
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-- that the length be the number of ub4's in the key
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--------------------------------------------------------------------
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*/
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template<typename UB4Traits>
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inline ub4 hash2(
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const ub4 *k, /* the key */
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ub4 length, /* the length of the key, in ub4s */
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ub4 initval, /* the previous hash, or an arbitrary value */
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const UB4Traits& ub4traits
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)
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{
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register ub4 a,b,c,len;
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/* Set up the internal state */
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len = length;
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a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */
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c = initval; /* the previous hash value */
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/*---------------------------------------- handle most of the key */
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while (len >= 3)
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{
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a += UB4Traits::as_ub4(k[0]);
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b += UB4Traits::as_ub4(k[1]);
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c += UB4Traits::as_ub4(k[2]);
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mix(a,b,c);
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k += 3; len -= 3;
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}
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/*-------------------------------------- handle the last 2 ub4's */
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c += length;
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switch(len) /* all the case statements fall through */
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{
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/* c is reserved for the length */
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case 2 : b += UB4Traits::as_ub4(k[1]);
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case 1 : a += UB4Traits::as_ub4(k[0]);
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/* case 0: nothing left to add */
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}
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mix(a,b,c);
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/*-------------------------------------------- report the result */
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return c;
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}
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typedef ub4 hash_t;
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inline hash_t hash_ub1(const ub1* key, std::size_t len, hash_t previous = 0)
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{
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return hash(key, ub4(len), previous, ub1_default_traits(), ub1x4_default_traits());
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}
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inline hash_t hash_ub1_nocase(const ub1* key, std::size_t len, hash_t previous = 0)
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{
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return hash(key, ub4(len), previous, ub1_nocase_traits(), ub1x4_nocase_traits());
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}
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template<typename UB4Traits>
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inline hash_t hash_ub4(const ub4* key, std::size_t len, const UB4Traits& traits, hash_t previous = 0)
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{
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return hash2(key,ub4(len), previous, traits);
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}
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inline ub4 hash_combine(ub4 left, ub4 right)
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{
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return hash_ub1(reinterpret_cast<const ub1*>(&left), 4, right);
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}
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template<typename POD>
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inline hash_t pod_hash(const POD& pod)
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{
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return hash_ub1(reinterpret_cast<const ub1*>(&pod), sizeof(POD));
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}
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inline hash_t string_hash(const char* string, hash_t previous = 0)
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{
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return hash_ub1(reinterpret_cast<const ub1*>(string), string_length(string), previous);
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}
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inline hash_t string_hash_nocase(const char* string, hash_t previous = 0)
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{
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return hash_ub1_nocase(reinterpret_cast<const ub1*>(string), string_length(string), previous);
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}
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struct RawStringHash
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{
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typedef hash_t hash_type;
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hash_type operator()(const char* string) const
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{
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return string_hash(string);
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}
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};
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struct HashString
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{
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typedef hash_t hash_type;
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hash_type operator()(const CopiedString& string) const
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{
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return string_hash(string.c_str());
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}
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};
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struct HashStringNoCase
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{
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typedef hash_t hash_type;
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hash_type operator()(const CopiedString& string) const
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{
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return string_hash_nocase(string.c_str());
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}
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};
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/// \brief Length of a string in ub4.
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/// "wibble" (6) gives 2,
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/// "and" (3) gives 1,
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/// "bleh" (4) gives 2
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inline std::size_t string_length_ub4(const char* string)
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{
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return ((string_length(string)>>2)+1)<<2;
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}
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/// \brief Hashable key type that stores a string as an array of ub4 - making hashing faster.
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/// Also caches the 32-bit result of the hash to speed up comparison of keys.
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template<typename UB4Traits = ub4_default_traits>
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class HashKey
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{
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Array<ub4> m_key;
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hash_t m_hash;
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void copy(const HashKey& other)
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{
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std::copy(other.m_key.begin(), other.m_key.end(), m_key.begin());
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m_hash = other.m_hash;
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}
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void copy(const char* string)
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{
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strncpy(reinterpret_cast<char*>(m_key.data()), string, m_key.size());
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for(Array<ub4>::iterator i = m_key.begin(); i != m_key.end(); ++i)
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{
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*i = UB4Traits::as_ub4(*i);
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}
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m_hash = hash_ub4(m_key.data(), m_key.size(), ub4_default_traits());
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}
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bool equal(const HashKey& other) const
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{
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return m_hash == other.m_hash && m_key.size() == other.m_key.size()
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&& std::equal(m_key.begin(), m_key.end(), other.m_key.begin());
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}
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public:
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HashKey(const HashKey& other) : m_key(other.m_key.size())
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{
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copy(other);
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}
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HashKey(const char* string) : m_key(string_length_ub4(string))
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{
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copy(string);
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}
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HashKey& operator=(const char* string)
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{
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m_key.resize(string_length_ub4(string));
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copy(string);
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return *this;
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}
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bool operator==(const HashKey& other) const
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{
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return equal(other);
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}
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bool operator!=(const HashKey& other) const
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{
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return !equal(other);
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}
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hash_t hash() const
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{
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return m_hash;
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}
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#if 0
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const char* c_str() const
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{
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return reinterpret_cast<const char*>(m_key.data());
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}
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#endif
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};
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/// \brief Hash function to use with HashKey.
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struct HashKeyHasher
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{
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typedef hash_t hash_type;
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hash_type operator()(const HashKey<ub4_default_traits>& key) const
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{
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return key.hash();
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}
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};
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#endif
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