forked from bartvdbraak/blender
155 lines
4.0 KiB
C++
155 lines
4.0 KiB
C++
/*
|
|
* ***** BEGIN GPL LICENSE BLOCK *****
|
|
*
|
|
* This program 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 2
|
|
* of the License, or (at your option) any later version.
|
|
*
|
|
* This program 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 this program; if not, write to the Free Software Foundation,
|
|
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
|
*
|
|
* The Original Code is Copyright (C) 2001-2002 by NaN Holding BV.
|
|
* All rights reserved.
|
|
*
|
|
* The Original Code is: all of this file.
|
|
*
|
|
* Contributor(s): none yet.
|
|
*
|
|
* ***** END GPL LICENSE BLOCK *****
|
|
*/
|
|
|
|
/** \file string/STR_HashedString.h
|
|
* \ingroup string
|
|
*/
|
|
|
|
|
|
/**
|
|
|
|
* Copyright (C) 2001 NaN Technologies B.V.
|
|
* This file was formerly known as: GEN_StdString.cpp.
|
|
* @date November, 14, 2001
|
|
*/
|
|
|
|
#ifndef __STR_HASHSTRING
|
|
#define __STR_HASHSTRING
|
|
|
|
#include "STR_String.h"
|
|
|
|
|
|
// Hash Mix utility function, by Bob Jenkins - Mix 3 32-bit values reversibly
|
|
//
|
|
// - If gHashMix() is run forward or backward, at least 32 bits in a,b,c have at
|
|
// least 1/4 probability of changing.
|
|
//
|
|
// - If gHashMix() is run forward, every bit of c will change between 1/3 and
|
|
// 2/3 of the time.
|
|
//
|
|
static inline void STR_gHashMix(dword& a, dword& b, dword& c)
|
|
{
|
|
a -= b; a -= c; a ^= (c>>13);
|
|
b -= c; b -= a; b ^= (a<<8);
|
|
c -= a; c -= b; c ^= (b>>13);
|
|
a -= b; a -= c; a ^= (c>>12);
|
|
b -= c; b -= a; b ^= (a<<16);
|
|
c -= a; c -= b; c ^= (b>>5);
|
|
a -= b; a -= c; a ^= (c>>3);
|
|
b -= c; b -= a; b ^= (a<<10);
|
|
c -= a; c -= b; c ^= (b>>15);
|
|
}
|
|
|
|
//
|
|
// Fast Hashable<int32> functionality
|
|
// http://www.concentric.net/~Ttwang/tech/inthash.htm
|
|
//
|
|
static inline dword STR_gHash(dword inDWord)
|
|
{
|
|
dword key = inDWord;
|
|
key += ~(key << 16);
|
|
key ^= (key >> 5);
|
|
key += (key << 3);
|
|
key ^= (key >> 13);
|
|
key += ~(key << 9);
|
|
key ^= (key >> 17);
|
|
return key;
|
|
}
|
|
|
|
enum { GOLDEN_RATIO = 0x9e3779b9 }; // arbitrary value to initialize hash funtion, well not so arbitrary
|
|
// as this value is taken from the pigs library (Orange Games/Lost Boys)
|
|
|
|
|
|
|
|
static dword STR_gHash(const void* in, int len, dword init_val)
|
|
{
|
|
unsigned int length = len;
|
|
dword a = (dword)GOLDEN_RATIO;
|
|
dword b = (dword)GOLDEN_RATIO;
|
|
dword c = init_val; // the previous hash value
|
|
byte *p_in = (byte *)in;
|
|
|
|
// Do the largest part of the key
|
|
while (length >= 12)
|
|
{
|
|
a += (p_in[0] + ((dword)p_in[1]<<8) + ((dword)p_in[2] <<16) + ((dword)p_in[3] <<24));
|
|
b += (p_in[4] + ((dword)p_in[5]<<8) + ((dword)p_in[6] <<16) + ((dword)p_in[7] <<24));
|
|
c += (p_in[8] + ((dword)p_in[9]<<8) + ((dword)p_in[10]<<16) + ((dword)p_in[11]<<24));
|
|
STR_gHashMix(a, b, c);
|
|
p_in += 12; length -= 12;
|
|
}
|
|
|
|
// Handle the last 11 bytes
|
|
c += len;
|
|
switch(length) {
|
|
case 11: c+=((dword)p_in[10]<<24);
|
|
case 10: c+=((dword)p_in[9]<<16);
|
|
case 9 : c+=((dword)p_in[8]<<8); // the first byte of c is reserved for the length
|
|
case 8 : b+=((dword)p_in[7]<<24);
|
|
case 7 : b+=((dword)p_in[6]<<16);
|
|
case 6 : b+=((dword)p_in[5]<<8);
|
|
case 5 : b+=p_in[4];
|
|
case 4 : a+=((dword)p_in[3]<<24);
|
|
case 3 : a+=((dword)p_in[2]<<16);
|
|
case 2 : a+=((dword)p_in[1]<<8);
|
|
case 1 : a+=p_in[0];
|
|
}
|
|
STR_gHashMix(a, b, c);
|
|
|
|
return c;
|
|
}
|
|
|
|
|
|
|
|
|
|
class STR_HashedString : public STR_String
|
|
{
|
|
public:
|
|
STR_HashedString() : STR_String(),m_Hashed(false) {}
|
|
STR_HashedString(const char* str) : STR_String(str),m_Hashed(false) {}
|
|
STR_HashedString(const STR_String& str) : STR_String(str),m_Hashed(false) {}
|
|
|
|
inline dword hash(dword init=0) const
|
|
{
|
|
if (!m_Hashed)
|
|
{
|
|
const char* str = *this;
|
|
int length = this->Length();
|
|
m_CachedHash = STR_gHash(str,length,init);
|
|
m_Hashed=true;
|
|
}
|
|
return m_CachedHash;
|
|
}
|
|
|
|
private:
|
|
mutable bool m_Hashed;
|
|
mutable dword m_CachedHash;
|
|
};
|
|
|
|
#endif //__STR_HASHSTRING
|
|
|