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comparison: security/nss/lib/dbm/src/h_func.c
security/nss/lib/dbm/src/h_func.c
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- TOR_BUG_9701
- changeset 15
- b8a032363ba2
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| -1:000000000000 | 0:a3fdcf412a10 |
|---|---|
| 1 /*- | |
| 2 * Copyright (c) 1990, 1993 | |
| 3 * The Regents of the University of California. All rights reserved. | |
| 4 * | |
| 5 * This code is derived from software contributed to Berkeley by | |
| 6 * Margo Seltzer. | |
| 7 * | |
| 8 * Redistribution and use in source and binary forms, with or without | |
| 9 * modification, are permitted provided that the following conditions | |
| 10 * are met: | |
| 11 * 1. Redistributions of source code must retain the above copyright | |
| 12 * notice, this list of conditions and the following disclaimer. | |
| 13 * 2. Redistributions in binary form must reproduce the above copyright | |
| 14 * notice, this list of conditions and the following disclaimer in the | |
| 15 * documentation and/or other materials provided with the distribution. | |
| 16 * 3. ***REMOVED*** - see | |
| 17 * ftp://ftp.cs.berkeley.edu/pub/4bsd/README.Impt.License.Change | |
| 18 * 4. Neither the name of the University nor the names of its contributors | |
| 19 * may be used to endorse or promote products derived from this software | |
| 20 * without specific prior written permission. | |
| 21 * | |
| 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND | |
| 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
| 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
| 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE | |
| 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
| 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
| 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
| 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
| 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
| 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
| 32 * SUCH DAMAGE. | |
| 33 */ | |
| 34 | |
| 35 #if defined(LIBC_SCCS) && !defined(lint) | |
| 36 static char sccsid[] = "@(#)hash_func.c 8.2 (Berkeley) 2/21/94"; | |
| 37 #endif /* LIBC_SCCS and not lint */ | |
| 38 | |
| 39 #ifndef macintosh | |
| 40 #include <sys/types.h> | |
| 41 #endif | |
| 42 #include "mcom_db.h" | |
| 43 #include "hash.h" | |
| 44 #include "page.h" | |
| 45 /* #include "extern.h" */ | |
| 46 | |
| 47 #if 0 | |
| 48 static uint32 hash1 __P((const void *, size_t)); | |
| 49 static uint32 hash2 __P((const void *, size_t)); | |
| 50 static uint32 hash3 __P((const void *, size_t)); | |
| 51 #endif | |
| 52 static uint32 hash4 __P((const void *, size_t)); | |
| 53 | |
| 54 /* Global default hash function */ | |
| 55 uint32 (*__default_hash) __P((const void *, size_t)) = hash4; | |
| 56 | |
| 57 /* | |
| 58 * HASH FUNCTIONS | |
| 59 * | |
| 60 * Assume that we've already split the bucket to which this key hashes, | |
| 61 * calculate that bucket, and check that in fact we did already split it. | |
| 62 * | |
| 63 * This came from ejb's hsearch. | |
| 64 */ | |
| 65 | |
| 66 #define PRIME1 37 | |
| 67 #define PRIME2 1048583 | |
| 68 | |
| 69 #if 0 | |
| 70 static uint32 | |
| 71 hash1(const void *keyarg, register size_t len) | |
| 72 { | |
| 73 register const uint8 *key; | |
| 74 register uint32 h; | |
| 75 | |
| 76 /* Convert string to integer */ | |
| 77 for (key = (const uint8 *)keyarg, h = 0; len--;) | |
| 78 h = h * PRIME1 ^ (*key++ - ' '); | |
| 79 h %= PRIME2; | |
| 80 return (h); | |
| 81 } | |
| 82 | |
| 83 /* | |
| 84 * Phong's linear congruential hash | |
| 85 */ | |
| 86 #define dcharhash(h, c) ((h) = 0x63c63cd9*(h) + 0x9c39c33d + (c)) | |
| 87 | |
| 88 static uint32 | |
| 89 hash2(const void *keyarg, size_t len) | |
| 90 { | |
| 91 register const uint8 *e, *key; | |
| 92 register uint32 h; | |
| 93 register uint8 c; | |
| 94 | |
| 95 key = (const uint8 *)keyarg; | |
| 96 e = key + len; | |
| 97 for (h = 0; key != e;) { | |
| 98 c = *key++; | |
| 99 if (!c && key > e) | |
| 100 break; | |
| 101 dcharhash(h, c); | |
| 102 } | |
| 103 return (h); | |
| 104 } | |
| 105 | |
| 106 /* | |
| 107 * This is INCREDIBLY ugly, but fast. We break the string up into 8 byte | |
| 108 * units. On the first time through the loop we get the "leftover bytes" | |
| 109 * (strlen % 8). On every other iteration, we perform 8 HASHC's so we handle | |
| 110 * all 8 bytes. Essentially, this saves us 7 cmp & branch instructions. If | |
| 111 * this routine is heavily used enough, it's worth the ugly coding. | |
| 112 * | |
| 113 * OZ's original sdbm hash | |
| 114 */ | |
| 115 static uint32 | |
| 116 hash3(const void *keyarg, register size_t len) | |
| 117 { | |
| 118 register const uint8 *key; | |
| 119 register size_t loop; | |
| 120 register uint32 h; | |
| 121 | |
| 122 #define HASHC h = *key++ + 65599 * h | |
| 123 | |
| 124 h = 0; | |
| 125 key = (const uint8 *)keyarg; | |
| 126 if (len > 0) { | |
| 127 loop = (len + 8 - 1) >> 3; | |
| 128 | |
| 129 switch (len & (8 - 1)) { | |
| 130 case 0: | |
| 131 do { | |
| 132 HASHC; | |
| 133 /* FALLTHROUGH */ | |
| 134 case 7: | |
| 135 HASHC; | |
| 136 /* FALLTHROUGH */ | |
| 137 case 6: | |
| 138 HASHC; | |
| 139 /* FALLTHROUGH */ | |
| 140 case 5: | |
| 141 HASHC; | |
| 142 /* FALLTHROUGH */ | |
| 143 case 4: | |
| 144 HASHC; | |
| 145 /* FALLTHROUGH */ | |
| 146 case 3: | |
| 147 HASHC; | |
| 148 /* FALLTHROUGH */ | |
| 149 case 2: | |
| 150 HASHC; | |
| 151 /* FALLTHROUGH */ | |
| 152 case 1: | |
| 153 HASHC; | |
| 154 } while (--loop); | |
| 155 } | |
| 156 } | |
| 157 return (h); | |
| 158 } | |
| 159 #endif /* 0 */ | |
| 160 | |
| 161 /* Hash function from Chris Torek. */ | |
| 162 static uint32 | |
| 163 hash4(const void *keyarg, register size_t len) | |
| 164 { | |
| 165 register const uint8 *key; | |
| 166 register size_t loop; | |
| 167 register uint32 h; | |
| 168 | |
| 169 #define HASH4a h = (h << 5) - h + *key++; | |
| 170 #define HASH4b h = (h << 5) + h + *key++; | |
| 171 #define HASH4 HASH4b | |
| 172 | |
| 173 h = 0; | |
| 174 key = (const uint8 *)keyarg; | |
| 175 if (len > 0) { | |
| 176 loop = (len + 8 - 1) >> 3; | |
| 177 | |
| 178 switch (len & (8 - 1)) { | |
| 179 case 0: | |
| 180 do { | |
| 181 HASH4; | |
| 182 /* FALLTHROUGH */ | |
| 183 case 7: | |
| 184 HASH4; | |
| 185 /* FALLTHROUGH */ | |
| 186 case 6: | |
| 187 HASH4; | |
| 188 /* FALLTHROUGH */ | |
| 189 case 5: | |
| 190 HASH4; | |
| 191 /* FALLTHROUGH */ | |
| 192 case 4: | |
| 193 HASH4; | |
| 194 /* FALLTHROUGH */ | |
| 195 case 3: | |
| 196 HASH4; | |
| 197 /* FALLTHROUGH */ | |
| 198 case 2: | |
| 199 HASH4; | |
| 200 /* FALLTHROUGH */ | |
| 201 case 1: | |
| 202 HASH4; | |
| 203 } while (--loop); | |
| 204 } | |
| 205 } | |
| 206 return (h); | |
| 207 } |
