1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 1997-9, 2000, 2008, 2009 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
18 #include <libpspp/hash-functions.h>
25 /* Based on http://burtleburtle.net/bob/c/lookup3.c, by Bob
26 Jenkins <bob_jenkins@burtleburtle.net>, as retrieved on April
27 8, 2009. The license information there says the following:
28 "You can use this free for any purpose. It's in the public
29 domain. It has no warranty." and "You may use this code any
30 way you wish, private, educational, or commercial. It's
33 #define HASH_ROT(x, k) (((x) << (k)) | ((x) >> (32 - (k))))
35 #define HASH_MIX(a, b, c) \
38 a -= c; a ^= HASH_ROT (c, 4); c += b; \
39 b -= a; b ^= HASH_ROT (a, 6); a += c; \
40 c -= b; c ^= HASH_ROT (b, 8); b += a; \
41 a -= c; a ^= HASH_ROT (c, 16); c += b; \
42 b -= a; b ^= HASH_ROT (a, 19); a += c; \
43 c -= b; c ^= HASH_ROT (b, 4); b += a; \
47 #define HASH_FINAL(a, b, c) \
50 c ^= b; c -= HASH_ROT (b, 14); \
51 a ^= c; a -= HASH_ROT (c, 11); \
52 b ^= a; b -= HASH_ROT (a, 25); \
53 c ^= b; c -= HASH_ROT (b, 16); \
54 a ^= c; a -= HASH_ROT (c, 4); \
55 b ^= a; b -= HASH_ROT (a, 14); \
56 c ^= b; c -= HASH_ROT (b, 24); \
60 /* Returns a hash value for the N bytes starting at P, starting
63 hash_bytes (const void *p_, size_t n, unsigned int basis)
65 const uint8_t *p = p_;
69 a = b = c = 0xdeadbeef + n + basis;
95 /* Returns a hash value for null-terminated string S, starting
98 hash_string (const char *s, unsigned int basis)
100 return hash_bytes (s, strlen (s), basis);
103 /* Returns a hash value for null-terminated string S, with
104 lowercase and uppercase letters treated as equal, starting
107 hash_case_string (const char *s, unsigned int basis)
109 size_t n = strlen (s);
114 a = b = c = 0xdeadbeef + n + basis;
118 for (i = 0; i < 12; i++)
119 ((unsigned char *)tmp)[i] = toupper ((unsigned char) s[i]);
131 for (i = 0; i < n; i++)
132 ((unsigned char *)tmp)[i] = toupper ((unsigned char) s[i]);
138 HASH_FINAL (a, b, c);
142 /* Returns a hash value for integer X, starting from BASIS. */
144 hash_int (int x, unsigned int basis)
156 /* Returns a hash value for double D, starting from BASIS. */
158 hash_double (double d, unsigned int basis)
160 #if SIZEOF_DOUBLE == 8
164 a = b = c = 0xdeadbeef + 8 + basis;
169 HASH_FINAL (a, b, c);
171 #else /* SIZEOF_DOUBLE != 8 */
172 return hash_bytes (&d, sizeof d, basis);
173 #endif /* SIZEOF_DOUBLE != 8 */