1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
|
/**
* $Id: STR_HashedString.h,v 1.4 2002/12/26 18:25:17 mein Exp $
* ***** BEGIN GPL/BL DUAL 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. The Blender
* Foundation also sells licenses for use in proprietary software under
* the Blender License. See http://www.blender.org/BL/ for information
* about this.
*
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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/BL DUAL LICENSE BLOCK *****
*/
/**
* $Id: STR_HashedString.h,v 1.4 2002/12/26 18:25:17 mein Exp $
* 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
|
