blob: 27a348ea9b6e27a18e9abf939b3aae96c21f4b29 (
plain)
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
|
/* Copyright (c) 1997-2022 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Lesser General Public
License as published by the Free Software Foundation; either
version 2.1 of the License, or (at your option) any later version.
The GNU C Library 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
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public
License along with the GNU C Library; if not, see
<https://www.gnu.org/licenses/>. */
#include <nss.h>
/* This is from libc/db/hash/hash_func.c, hash3 is static there */
/*
* This is INCREDIBLY ugly, but fast. We break the string up into 8 byte
* units. On the first time through the loop we get the "leftover bytes"
* (strlen % 8). On every other iteration, we perform 8 HASHC's so we handle
* all 8 bytes. Essentially, this saves us 7 cmp & branch instructions. If
* this routine is heavily used enough, it's worth the ugly coding.
*
* OZ's original sdbm hash
*/
uint32_t
__nss_hash (const void *keyarg, size_t len)
{
const unsigned char *key;
size_t loop;
uint32_t h;
#define HASHC h = *key++ + 65599 * h
h = 0;
key = keyarg;
if (len > 0)
{
loop = (len + 8 - 1) >> 3;
switch (len & (8 - 1))
{
case 0:
do
{
HASHC;
/* FALLTHROUGH */
case 7:
HASHC;
/* FALLTHROUGH */
case 6:
HASHC;
/* FALLTHROUGH */
case 5:
HASHC;
/* FALLTHROUGH */
case 4:
HASHC;
/* FALLTHROUGH */
case 3:
HASHC;
/* FALLTHROUGH */
case 2:
HASHC;
/* FALLTHROUGH */
case 1:
HASHC;
}
while (--loop);
}
}
return h;
}
libc_hidden_def (__nss_hash)
|
