quadrilateralcowboy/idlib/containers/HashIndex.cpp
2020-06-12 14:06:25 -07:00

155 lines
4.1 KiB
C++

/*
===========================================================================
Doom 3 GPL Source Code
Copyright (C) 1999-2011 id Software LLC, a ZeniMax Media company.
This file is part of the Doom 3 GPL Source Code (?Doom 3 Source Code?).
Doom 3 Source Code 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.
Doom 3 Source Code 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 Doom 3 Source Code. If not, see <http://www.gnu.org/licenses/>.
In addition, the Doom 3 Source Code is also subject to certain additional terms. You should have received a copy of these additional terms immediately following the terms and conditions of the GNU General Public License which accompanied the Doom 3 Source Code. If not, please request a copy in writing from id Software at the address below.
If you have questions concerning this license or the applicable additional terms, you may contact in writing id Software LLC, c/o ZeniMax Media Inc., Suite 120, Rockville, Maryland 20850 USA.
===========================================================================
*/
#include "../precompiled.h"
#pragma hdrstop
int idHashIndex::INVALID_INDEX[1] = { -1 };
/*
================
idHashIndex::Init
================
*/
void idHashIndex::Init( const int initialHashSize, const int initialIndexSize ) {
assert( idMath::IsPowerOfTwo( initialHashSize ) );
hashSize = initialHashSize;
hash = INVALID_INDEX;
indexSize = initialIndexSize;
indexChain = INVALID_INDEX;
granularity = DEFAULT_HASH_GRANULARITY;
hashMask = hashSize - 1;
lookupMask = 0;
}
/*
================
idHashIndex::Allocate
================
*/
void idHashIndex::Allocate( const int newHashSize, const int newIndexSize ) {
assert( idMath::IsPowerOfTwo( newHashSize ) );
Free();
hashSize = newHashSize;
hash = new int[hashSize];
memset( hash, 0xff, hashSize * sizeof( hash[0] ) );
indexSize = newIndexSize;
indexChain = new int[indexSize];
memset( indexChain, 0xff, indexSize * sizeof( indexChain[0] ) );
hashMask = hashSize - 1;
lookupMask = -1;
}
/*
================
idHashIndex::Free
================
*/
void idHashIndex::Free( void ) {
if ( hash != INVALID_INDEX ) {
delete[] hash;
hash = INVALID_INDEX;
}
if ( indexChain != INVALID_INDEX ) {
delete[] indexChain;
indexChain = INVALID_INDEX;
}
lookupMask = 0;
}
/*
================
idHashIndex::ResizeIndex
================
*/
void idHashIndex::ResizeIndex( const int newIndexSize ) {
int *oldIndexChain, mod, newSize;
if ( newIndexSize <= indexSize ) {
return;
}
mod = newIndexSize % granularity;
if ( !mod ) {
newSize = newIndexSize;
} else {
newSize = newIndexSize + granularity - mod;
}
if ( indexChain == INVALID_INDEX ) {
indexSize = newSize;
return;
}
oldIndexChain = indexChain;
indexChain = new int[newSize];
memcpy( indexChain, oldIndexChain, indexSize * sizeof(int) );
memset( indexChain + indexSize, 0xff, (newSize - indexSize) * sizeof(int) );
delete[] oldIndexChain;
indexSize = newSize;
}
/*
================
idHashIndex::GetSpread
================
*/
int idHashIndex::GetSpread( void ) const {
int i, index, totalItems, *numHashItems, average, error, e;
if ( hash == INVALID_INDEX ) {
return 100;
}
totalItems = 0;
numHashItems = new int[hashSize];
for ( i = 0; i < hashSize; i++ ) {
numHashItems[i] = 0;
for ( index = hash[i]; index >= 0; index = indexChain[index] ) {
numHashItems[i]++;
}
totalItems += numHashItems[i];
}
// if no items in hash
if ( totalItems <= 1 ) {
delete[] numHashItems;
return 100;
}
average = totalItems / hashSize;
error = 0;
for ( i = 0; i < hashSize; i++ ) {
e = abs( numHashItems[i] - average );
if ( e > 1 ) {
error += e - 1;
}
}
delete[] numHashItems;
return 100 - (error * 100 / totalItems);
}