Tesseract
3.02
Main Page
Related Pages
Modules
Namespaces
Classes
Files
File List
File Members
All
Classes
Namespaces
Files
Functions
Variables
Typedefs
Enumerations
Enumerator
Friends
Macros
Groups
Pages
hashfn.cpp
Go to the documentation of this file.
1
/**********************************************************************
2
* File: hashfn.c (Formerly hash.c)
3
* Description: Simple hash function.
4
* Author: Ray Smith
5
* Created: Thu Jan 16 11:47:59 GMT 1992
6
*
7
* (C) Copyright 1992, Hewlett-Packard Ltd.
8
** Licensed under the Apache License, Version 2.0 (the "License");
9
** you may not use this file except in compliance with the License.
10
** You may obtain a copy of the License at
11
** http://www.apache.org/licenses/LICENSE-2.0
12
** Unless required by applicable law or agreed to in writing, software
13
** distributed under the License is distributed on an "AS IS" BASIS,
14
** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
15
** See the License for the specific language governing permissions and
16
** limitations under the License.
17
*
18
**********************************************************************/
19
20
#include "
mfcpch.h
"
//precompiled headers
21
#include "
hashfn.h
"
22
23
/**********************************************************************
24
* hash
25
*
26
* Simple hash function working on power of 2 table sizes.
27
* Uses xor function. Needs linear rehash.
28
**********************************************************************/
29
30
inT32
hash
(
//hash function
31
inT32
bits,
//bits in hash function
32
void
*key,
//key to hash
33
inT32
keysize
//size of key
34
) {
35
inT32
bitindex;
//current bit count
36
uinT32
keybits;
//bit buffer
37
uinT32
hcode;
//current hash code
38
uinT32
mask;
//bit mask
39
40
mask = (1 << bits) - 1;
41
keysize *= 8;
//in bits
42
bitindex = 0;
43
keybits = 0;
44
hcode = 0;
45
do
{
46
while
(keysize > 0 && bitindex <= 24) {
47
keybits |= *((
uinT8
*) key) << bitindex;
48
key = (
uinT8
*) key + 1;
49
bitindex += 8;
50
keysize -= 8;
51
}
52
hcode ^= keybits & mask;
//key new key
53
keybits >>= bits;
54
}
55
while
(keysize > 0);
56
return
hcode;
//initial hash
57
}
mnt
data
src
tesseract-ocr
ccutil
hashfn.cpp
Generated on Thu Nov 1 2012 20:19:45 for Tesseract by
1.8.1