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annotate libiberty/hashtab.c @ 158:494b0b89df80 default tip
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| author | Shinji KONO <kono@ie.u-ryukyu.ac.jp> |
|---|---|
| date | Mon, 25 May 2020 18:13:55 +0900 |
| parents | 1830386684a0 |
| children |
| rev | line source |
|---|---|
| 0 | 1 /* An expandable hash tables datatype. |
| 145 | 2 Copyright (C) 1999-2020 Free Software Foundation, Inc. |
| 0 | 3 Contributed by Vladimir Makarov (vmakarov@cygnus.com). |
| 4 | |
| 5 This file is part of the libiberty library. | |
| 6 Libiberty is free software; you can redistribute it and/or | |
| 7 modify it under the terms of the GNU Library General Public | |
| 8 License as published by the Free Software Foundation; either | |
| 9 version 2 of the License, or (at your option) any later version. | |
| 10 | |
| 11 Libiberty is distributed in the hope that it will be useful, | |
| 12 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
| 14 Library General Public License for more details. | |
| 15 | |
| 16 You should have received a copy of the GNU Library General Public | |
| 17 License along with libiberty; see the file COPYING.LIB. If | |
| 18 not, write to the Free Software Foundation, Inc., 51 Franklin Street - Fifth Floor, | |
| 19 Boston, MA 02110-1301, USA. */ | |
| 20 | |
| 21 /* This package implements basic hash table functionality. It is possible | |
| 22 to search for an entry, create an entry and destroy an entry. | |
| 23 | |
| 24 Elements in the table are generic pointers. | |
| 25 | |
| 26 The size of the table is not fixed; if the occupancy of the table | |
| 27 grows too high the hash table will be expanded. | |
| 28 | |
| 29 The abstract data implementation is based on generalized Algorithm D | |
| 30 from Knuth's book "The art of computer programming". Hash table is | |
| 31 expanded by creation of new hash table and transferring elements from | |
| 32 the old table to the new table. */ | |
| 33 | |
| 34 #ifdef HAVE_CONFIG_H | |
| 35 #include "config.h" | |
| 36 #endif | |
| 37 | |
| 38 #include <sys/types.h> | |
| 39 | |
| 40 #ifdef HAVE_STDLIB_H | |
| 41 #include <stdlib.h> | |
| 42 #endif | |
| 43 #ifdef HAVE_STRING_H | |
| 44 #include <string.h> | |
| 45 #endif | |
| 46 #ifdef HAVE_MALLOC_H | |
| 47 #include <malloc.h> | |
| 48 #endif | |
| 49 #ifdef HAVE_LIMITS_H | |
| 50 #include <limits.h> | |
| 51 #endif | |
|
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52 #ifdef HAVE_INTTYPES_H |
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53 #include <inttypes.h> |
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54 #endif |
| 0 | 55 #ifdef HAVE_STDINT_H |
| 56 #include <stdint.h> | |
| 57 #endif | |
| 58 | |
| 59 #include <stdio.h> | |
| 60 | |
| 61 #include "libiberty.h" | |
| 62 #include "ansidecl.h" | |
| 63 #include "hashtab.h" | |
| 64 | |
| 65 #ifndef CHAR_BIT | |
| 66 #define CHAR_BIT 8 | |
| 67 #endif | |
| 68 | |
| 69 static unsigned int higher_prime_index (unsigned long); | |
| 70 static hashval_t htab_mod_1 (hashval_t, hashval_t, hashval_t, int); | |
| 71 static hashval_t htab_mod (hashval_t, htab_t); | |
| 72 static hashval_t htab_mod_m2 (hashval_t, htab_t); | |
| 73 static hashval_t hash_pointer (const void *); | |
| 74 static int eq_pointer (const void *, const void *); | |
| 75 static int htab_expand (htab_t); | |
| 76 static PTR *find_empty_slot_for_expand (htab_t, hashval_t); | |
| 77 | |
| 78 /* At some point, we could make these be NULL, and modify the | |
| 79 hash-table routines to handle NULL specially; that would avoid | |
| 80 function-call overhead for the common case of hashing pointers. */ | |
| 81 htab_hash htab_hash_pointer = hash_pointer; | |
| 82 htab_eq htab_eq_pointer = eq_pointer; | |
| 83 | |
| 84 /* Table of primes and multiplicative inverses. | |
| 85 | |
| 86 Note that these are not minimally reduced inverses. Unlike when generating | |
| 87 code to divide by a constant, we want to be able to use the same algorithm | |
| 88 all the time. All of these inverses (are implied to) have bit 32 set. | |
| 89 | |
| 90 For the record, here's the function that computed the table; it's a | |
| 91 vastly simplified version of the function of the same name from gcc. */ | |
| 92 | |
| 93 #if 0 | |
| 94 unsigned int | |
| 95 ceil_log2 (unsigned int x) | |
| 96 { | |
| 97 int i; | |
| 98 for (i = 31; i >= 0 ; --i) | |
| 99 if (x > (1u << i)) | |
| 100 return i+1; | |
| 101 abort (); | |
| 102 } | |
| 103 | |
| 104 unsigned int | |
| 105 choose_multiplier (unsigned int d, unsigned int *mlp, unsigned char *shiftp) | |
| 106 { | |
| 107 unsigned long long mhigh; | |
| 108 double nx; | |
| 109 int lgup, post_shift; | |
| 110 int pow, pow2; | |
| 111 int n = 32, precision = 32; | |
| 112 | |
| 113 lgup = ceil_log2 (d); | |
| 114 pow = n + lgup; | |
| 115 pow2 = n + lgup - precision; | |
| 116 | |
| 117 nx = ldexp (1.0, pow) + ldexp (1.0, pow2); | |
| 118 mhigh = nx / d; | |
| 119 | |
| 120 *shiftp = lgup - 1; | |
| 121 *mlp = mhigh; | |
| 122 return mhigh >> 32; | |
| 123 } | |
| 124 #endif | |
| 125 | |
| 126 struct prime_ent | |
| 127 { | |
| 128 hashval_t prime; | |
| 129 hashval_t inv; | |
| 130 hashval_t inv_m2; /* inverse of prime-2 */ | |
| 131 hashval_t shift; | |
| 132 }; | |
| 133 | |
| 134 static struct prime_ent const prime_tab[] = { | |
| 135 { 7, 0x24924925, 0x9999999b, 2 }, | |
| 136 { 13, 0x3b13b13c, 0x745d1747, 3 }, | |
| 137 { 31, 0x08421085, 0x1a7b9612, 4 }, | |
| 138 { 61, 0x0c9714fc, 0x15b1e5f8, 5 }, | |
| 139 { 127, 0x02040811, 0x0624dd30, 6 }, | |
| 140 { 251, 0x05197f7e, 0x073260a5, 7 }, | |
| 141 { 509, 0x01824366, 0x02864fc8, 8 }, | |
| 142 { 1021, 0x00c0906d, 0x014191f7, 9 }, | |
| 143 { 2039, 0x0121456f, 0x0161e69e, 10 }, | |
| 144 { 4093, 0x00300902, 0x00501908, 11 }, | |
| 145 { 8191, 0x00080041, 0x00180241, 12 }, | |
| 146 { 16381, 0x000c0091, 0x00140191, 13 }, | |
| 147 { 32749, 0x002605a5, 0x002a06e6, 14 }, | |
| 148 { 65521, 0x000f00e2, 0x00110122, 15 }, | |
| 149 { 131071, 0x00008001, 0x00018003, 16 }, | |
| 150 { 262139, 0x00014002, 0x0001c004, 17 }, | |
| 151 { 524287, 0x00002001, 0x00006001, 18 }, | |
| 152 { 1048573, 0x00003001, 0x00005001, 19 }, | |
| 153 { 2097143, 0x00004801, 0x00005801, 20 }, | |
| 154 { 4194301, 0x00000c01, 0x00001401, 21 }, | |
| 155 { 8388593, 0x00001e01, 0x00002201, 22 }, | |
| 156 { 16777213, 0x00000301, 0x00000501, 23 }, | |
| 157 { 33554393, 0x00001381, 0x00001481, 24 }, | |
| 158 { 67108859, 0x00000141, 0x000001c1, 25 }, | |
| 159 { 134217689, 0x000004e1, 0x00000521, 26 }, | |
| 160 { 268435399, 0x00000391, 0x000003b1, 27 }, | |
| 161 { 536870909, 0x00000019, 0x00000029, 28 }, | |
| 162 { 1073741789, 0x0000008d, 0x00000095, 29 }, | |
| 163 { 2147483647, 0x00000003, 0x00000007, 30 }, | |
| 164 /* Avoid "decimal constant so large it is unsigned" for 4294967291. */ | |
| 165 { 0xfffffffb, 0x00000006, 0x00000008, 31 } | |
| 166 }; | |
| 167 | |
| 168 /* The following function returns an index into the above table of the | |
| 169 nearest prime number which is greater than N, and near a power of two. */ | |
| 170 | |
| 171 static unsigned int | |
| 172 higher_prime_index (unsigned long n) | |
| 173 { | |
| 174 unsigned int low = 0; | |
| 175 unsigned int high = sizeof(prime_tab) / sizeof(prime_tab[0]); | |
| 176 | |
| 177 while (low != high) | |
| 178 { | |
| 179 unsigned int mid = low + (high - low) / 2; | |
| 180 if (n > prime_tab[mid].prime) | |
| 181 low = mid + 1; | |
| 182 else | |
| 183 high = mid; | |
| 184 } | |
| 185 | |
| 186 /* If we've run out of primes, abort. */ | |
| 187 if (n > prime_tab[low].prime) | |
| 188 { | |
| 189 fprintf (stderr, "Cannot find prime bigger than %lu\n", n); | |
| 190 abort (); | |
| 191 } | |
| 192 | |
| 193 return low; | |
| 194 } | |
| 195 | |
| 196 /* Returns non-zero if P1 and P2 are equal. */ | |
| 197 | |
| 198 static int | |
| 199 eq_pointer (const PTR p1, const PTR p2) | |
| 200 { | |
| 201 return p1 == p2; | |
| 202 } | |
| 203 | |
| 204 | |
| 205 /* The parens around the function names in the next two definitions | |
| 206 are essential in order to prevent macro expansions of the name. | |
| 207 The bodies, however, are expanded as expected, so they are not | |
| 208 recursive definitions. */ | |
| 209 | |
| 210 /* Return the current size of given hash table. */ | |
| 211 | |
| 212 #define htab_size(htab) ((htab)->size) | |
| 213 | |
| 214 size_t | |
| 215 (htab_size) (htab_t htab) | |
| 216 { | |
| 217 return htab_size (htab); | |
| 218 } | |
| 219 | |
| 220 /* Return the current number of elements in given hash table. */ | |
| 221 | |
| 222 #define htab_elements(htab) ((htab)->n_elements - (htab)->n_deleted) | |
| 223 | |
| 224 size_t | |
| 225 (htab_elements) (htab_t htab) | |
| 226 { | |
| 227 return htab_elements (htab); | |
| 228 } | |
| 229 | |
| 230 /* Return X % Y. */ | |
| 231 | |
| 232 static inline hashval_t | |
| 233 htab_mod_1 (hashval_t x, hashval_t y, hashval_t inv, int shift) | |
| 234 { | |
| 235 /* The multiplicative inverses computed above are for 32-bit types, and | |
| 236 requires that we be able to compute a highpart multiply. */ | |
| 237 #ifdef UNSIGNED_64BIT_TYPE | |
| 238 __extension__ typedef UNSIGNED_64BIT_TYPE ull; | |
| 239 if (sizeof (hashval_t) * CHAR_BIT <= 32) | |
| 240 { | |
| 241 hashval_t t1, t2, t3, t4, q, r; | |
| 242 | |
| 243 t1 = ((ull)x * inv) >> 32; | |
| 244 t2 = x - t1; | |
| 245 t3 = t2 >> 1; | |
| 246 t4 = t1 + t3; | |
| 247 q = t4 >> shift; | |
| 248 r = x - (q * y); | |
| 249 | |
| 250 return r; | |
| 251 } | |
| 252 #endif | |
| 253 | |
| 254 /* Otherwise just use the native division routines. */ | |
| 255 return x % y; | |
| 256 } | |
| 257 | |
| 258 /* Compute the primary hash for HASH given HTAB's current size. */ | |
| 259 | |
| 260 static inline hashval_t | |
| 261 htab_mod (hashval_t hash, htab_t htab) | |
| 262 { | |
| 263 const struct prime_ent *p = &prime_tab[htab->size_prime_index]; | |
| 264 return htab_mod_1 (hash, p->prime, p->inv, p->shift); | |
| 265 } | |
| 266 | |
| 267 /* Compute the secondary hash for HASH given HTAB's current size. */ | |
| 268 | |
| 269 static inline hashval_t | |
| 270 htab_mod_m2 (hashval_t hash, htab_t htab) | |
| 271 { | |
| 272 const struct prime_ent *p = &prime_tab[htab->size_prime_index]; | |
| 273 return 1 + htab_mod_1 (hash, p->prime - 2, p->inv_m2, p->shift); | |
| 274 } | |
| 275 | |
| 276 /* This function creates table with length slightly longer than given | |
| 277 source length. Created hash table is initiated as empty (all the | |
| 278 hash table entries are HTAB_EMPTY_ENTRY). The function returns the | |
| 279 created hash table, or NULL if memory allocation fails. */ | |
| 280 | |
| 281 htab_t | |
| 282 htab_create_alloc (size_t size, htab_hash hash_f, htab_eq eq_f, | |
| 283 htab_del del_f, htab_alloc alloc_f, htab_free free_f) | |
| 284 { | |
|
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285 return htab_create_typed_alloc (size, hash_f, eq_f, del_f, alloc_f, alloc_f, |
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286 free_f); |
| 0 | 287 } |
| 288 | |
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289 /* As above, but uses the variants of ALLOC_F and FREE_F which accept |
| 0 | 290 an extra argument. */ |
| 291 | |
| 292 htab_t | |
| 293 htab_create_alloc_ex (size_t size, htab_hash hash_f, htab_eq eq_f, | |
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294 htab_del del_f, void *alloc_arg, |
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295 htab_alloc_with_arg alloc_f, |
| 0 | 296 htab_free_with_arg free_f) |
| 297 { | |
| 298 htab_t result; | |
| 299 unsigned int size_prime_index; | |
| 300 | |
| 301 size_prime_index = higher_prime_index (size); | |
| 302 size = prime_tab[size_prime_index].prime; | |
| 303 | |
| 304 result = (htab_t) (*alloc_f) (alloc_arg, 1, sizeof (struct htab)); | |
| 305 if (result == NULL) | |
| 306 return NULL; | |
| 307 result->entries = (PTR *) (*alloc_f) (alloc_arg, size, sizeof (PTR)); | |
| 308 if (result->entries == NULL) | |
| 309 { | |
| 310 if (free_f != NULL) | |
| 311 (*free_f) (alloc_arg, result); | |
| 312 return NULL; | |
| 313 } | |
| 314 result->size = size; | |
| 315 result->size_prime_index = size_prime_index; | |
| 316 result->hash_f = hash_f; | |
| 317 result->eq_f = eq_f; | |
| 318 result->del_f = del_f; | |
| 319 result->alloc_arg = alloc_arg; | |
| 320 result->alloc_with_arg_f = alloc_f; | |
| 321 result->free_with_arg_f = free_f; | |
| 322 return result; | |
| 323 } | |
| 324 | |
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325 /* |
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326 |
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327 @deftypefn Supplemental htab_t htab_create_typed_alloc (size_t @var{size}, @ |
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328 htab_hash @var{hash_f}, htab_eq @var{eq_f}, htab_del @var{del_f}, @ |
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329 htab_alloc @var{alloc_tab_f}, htab_alloc @var{alloc_f}, @ |
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330 htab_free @var{free_f}) |
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331 |
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332 This function creates a hash table that uses two different allocators |
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333 @var{alloc_tab_f} and @var{alloc_f} to use for allocating the table itself |
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334 and its entries respectively. This is useful when variables of different |
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335 types need to be allocated with different allocators. |
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336 |
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337 The created hash table is slightly larger than @var{size} and it is |
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338 initially empty (all the hash table entries are @code{HTAB_EMPTY_ENTRY}). |
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339 The function returns the created hash table, or @code{NULL} if memory |
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340 allocation fails. |
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341 |
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342 @end deftypefn |
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343 |
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344 */ |
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345 |
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346 htab_t |
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347 htab_create_typed_alloc (size_t size, htab_hash hash_f, htab_eq eq_f, |
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348 htab_del del_f, htab_alloc alloc_tab_f, |
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349 htab_alloc alloc_f, htab_free free_f) |
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350 { |
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351 htab_t result; |
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352 unsigned int size_prime_index; |
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353 |
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354 size_prime_index = higher_prime_index (size); |
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355 size = prime_tab[size_prime_index].prime; |
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356 |
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357 result = (htab_t) (*alloc_tab_f) (1, sizeof (struct htab)); |
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358 if (result == NULL) |
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359 return NULL; |
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360 result->entries = (PTR *) (*alloc_f) (size, sizeof (PTR)); |
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361 if (result->entries == NULL) |
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362 { |
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363 if (free_f != NULL) |
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364 (*free_f) (result); |
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365 return NULL; |
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366 } |
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367 result->size = size; |
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368 result->size_prime_index = size_prime_index; |
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369 result->hash_f = hash_f; |
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370 result->eq_f = eq_f; |
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371 result->del_f = del_f; |
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372 result->alloc_f = alloc_f; |
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373 result->free_f = free_f; |
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374 return result; |
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375 } |
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376 |
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377 |
| 0 | 378 /* Update the function pointers and allocation parameter in the htab_t. */ |
| 379 | |
| 380 void | |
| 381 htab_set_functions_ex (htab_t htab, htab_hash hash_f, htab_eq eq_f, | |
| 382 htab_del del_f, PTR alloc_arg, | |
| 383 htab_alloc_with_arg alloc_f, htab_free_with_arg free_f) | |
| 384 { | |
| 385 htab->hash_f = hash_f; | |
| 386 htab->eq_f = eq_f; | |
| 387 htab->del_f = del_f; | |
| 388 htab->alloc_arg = alloc_arg; | |
| 389 htab->alloc_with_arg_f = alloc_f; | |
| 390 htab->free_with_arg_f = free_f; | |
| 391 } | |
| 392 | |
| 393 /* These functions exist solely for backward compatibility. */ | |
| 394 | |
| 395 #undef htab_create | |
| 396 htab_t | |
| 397 htab_create (size_t size, htab_hash hash_f, htab_eq eq_f, htab_del del_f) | |
| 398 { | |
| 399 return htab_create_alloc (size, hash_f, eq_f, del_f, xcalloc, free); | |
| 400 } | |
| 401 | |
| 402 htab_t | |
| 403 htab_try_create (size_t size, htab_hash hash_f, htab_eq eq_f, htab_del del_f) | |
| 404 { | |
| 405 return htab_create_alloc (size, hash_f, eq_f, del_f, calloc, free); | |
| 406 } | |
| 407 | |
| 408 /* This function frees all memory allocated for given hash table. | |
| 409 Naturally the hash table must already exist. */ | |
| 410 | |
| 411 void | |
| 412 htab_delete (htab_t htab) | |
| 413 { | |
| 414 size_t size = htab_size (htab); | |
| 415 PTR *entries = htab->entries; | |
| 416 int i; | |
| 417 | |
| 418 if (htab->del_f) | |
| 419 for (i = size - 1; i >= 0; i--) | |
| 420 if (entries[i] != HTAB_EMPTY_ENTRY && entries[i] != HTAB_DELETED_ENTRY) | |
| 421 (*htab->del_f) (entries[i]); | |
| 422 | |
| 423 if (htab->free_f != NULL) | |
| 424 { | |
| 425 (*htab->free_f) (entries); | |
| 426 (*htab->free_f) (htab); | |
| 427 } | |
| 428 else if (htab->free_with_arg_f != NULL) | |
| 429 { | |
| 430 (*htab->free_with_arg_f) (htab->alloc_arg, entries); | |
| 431 (*htab->free_with_arg_f) (htab->alloc_arg, htab); | |
| 432 } | |
| 433 } | |
| 434 | |
| 435 /* This function clears all entries in the given hash table. */ | |
| 436 | |
| 437 void | |
| 438 htab_empty (htab_t htab) | |
| 439 { | |
| 440 size_t size = htab_size (htab); | |
| 441 PTR *entries = htab->entries; | |
| 442 int i; | |
| 443 | |
| 444 if (htab->del_f) | |
| 445 for (i = size - 1; i >= 0; i--) | |
| 446 if (entries[i] != HTAB_EMPTY_ENTRY && entries[i] != HTAB_DELETED_ENTRY) | |
| 447 (*htab->del_f) (entries[i]); | |
| 448 | |
| 449 /* Instead of clearing megabyte, downsize the table. */ | |
| 450 if (size > 1024*1024 / sizeof (PTR)) | |
| 451 { | |
| 452 int nindex = higher_prime_index (1024 / sizeof (PTR)); | |
| 453 int nsize = prime_tab[nindex].prime; | |
| 454 | |
| 455 if (htab->free_f != NULL) | |
| 456 (*htab->free_f) (htab->entries); | |
| 457 else if (htab->free_with_arg_f != NULL) | |
| 458 (*htab->free_with_arg_f) (htab->alloc_arg, htab->entries); | |
| 459 if (htab->alloc_with_arg_f != NULL) | |
| 460 htab->entries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize, | |
| 461 sizeof (PTR *)); | |
| 462 else | |
| 463 htab->entries = (PTR *) (*htab->alloc_f) (nsize, sizeof (PTR *)); | |
| 464 htab->size = nsize; | |
| 465 htab->size_prime_index = nindex; | |
| 466 } | |
| 467 else | |
| 468 memset (entries, 0, size * sizeof (PTR)); | |
| 469 htab->n_deleted = 0; | |
| 470 htab->n_elements = 0; | |
| 471 } | |
| 472 | |
| 473 /* Similar to htab_find_slot, but without several unwanted side effects: | |
| 474 - Does not call htab->eq_f when it finds an existing entry. | |
| 475 - Does not change the count of elements/searches/collisions in the | |
| 476 hash table. | |
| 477 This function also assumes there are no deleted entries in the table. | |
| 478 HASH is the hash value for the element to be inserted. */ | |
| 479 | |
| 480 static PTR * | |
| 481 find_empty_slot_for_expand (htab_t htab, hashval_t hash) | |
| 482 { | |
| 483 hashval_t index = htab_mod (hash, htab); | |
| 484 size_t size = htab_size (htab); | |
| 485 PTR *slot = htab->entries + index; | |
| 486 hashval_t hash2; | |
| 487 | |
| 488 if (*slot == HTAB_EMPTY_ENTRY) | |
| 489 return slot; | |
| 490 else if (*slot == HTAB_DELETED_ENTRY) | |
| 491 abort (); | |
| 492 | |
| 493 hash2 = htab_mod_m2 (hash, htab); | |
| 494 for (;;) | |
| 495 { | |
| 496 index += hash2; | |
| 497 if (index >= size) | |
| 498 index -= size; | |
| 499 | |
| 500 slot = htab->entries + index; | |
| 501 if (*slot == HTAB_EMPTY_ENTRY) | |
| 502 return slot; | |
| 503 else if (*slot == HTAB_DELETED_ENTRY) | |
| 504 abort (); | |
| 505 } | |
| 506 } | |
| 507 | |
| 508 /* The following function changes size of memory allocated for the | |
| 509 entries and repeatedly inserts the table elements. The occupancy | |
| 510 of the table after the call will be about 50%. Naturally the hash | |
| 511 table must already exist. Remember also that the place of the | |
| 512 table entries is changed. If memory allocation failures are allowed, | |
| 513 this function will return zero, indicating that the table could not be | |
| 514 expanded. If all goes well, it will return a non-zero value. */ | |
| 515 | |
| 516 static int | |
| 517 htab_expand (htab_t htab) | |
| 518 { | |
| 519 PTR *oentries; | |
| 520 PTR *olimit; | |
| 521 PTR *p; | |
| 522 PTR *nentries; | |
| 523 size_t nsize, osize, elts; | |
| 524 unsigned int oindex, nindex; | |
| 525 | |
| 526 oentries = htab->entries; | |
| 527 oindex = htab->size_prime_index; | |
| 528 osize = htab->size; | |
| 529 olimit = oentries + osize; | |
| 530 elts = htab_elements (htab); | |
| 531 | |
| 532 /* Resize only when table after removal of unused elements is either | |
| 533 too full or too empty. */ | |
| 534 if (elts * 2 > osize || (elts * 8 < osize && osize > 32)) | |
| 535 { | |
| 536 nindex = higher_prime_index (elts * 2); | |
| 537 nsize = prime_tab[nindex].prime; | |
| 538 } | |
| 539 else | |
| 540 { | |
| 541 nindex = oindex; | |
| 542 nsize = osize; | |
| 543 } | |
| 544 | |
| 545 if (htab->alloc_with_arg_f != NULL) | |
| 546 nentries = (PTR *) (*htab->alloc_with_arg_f) (htab->alloc_arg, nsize, | |
| 547 sizeof (PTR *)); | |
| 548 else | |
| 549 nentries = (PTR *) (*htab->alloc_f) (nsize, sizeof (PTR *)); | |
| 550 if (nentries == NULL) | |
| 551 return 0; | |
| 552 htab->entries = nentries; | |
| 553 htab->size = nsize; | |
| 554 htab->size_prime_index = nindex; | |
| 555 htab->n_elements -= htab->n_deleted; | |
| 556 htab->n_deleted = 0; | |
| 557 | |
| 558 p = oentries; | |
| 559 do | |
| 560 { | |
| 561 PTR x = *p; | |
| 562 | |
| 563 if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY) | |
| 564 { | |
| 565 PTR *q = find_empty_slot_for_expand (htab, (*htab->hash_f) (x)); | |
| 566 | |
| 567 *q = x; | |
| 568 } | |
| 569 | |
| 570 p++; | |
| 571 } | |
| 572 while (p < olimit); | |
| 573 | |
| 574 if (htab->free_f != NULL) | |
| 575 (*htab->free_f) (oentries); | |
| 576 else if (htab->free_with_arg_f != NULL) | |
| 577 (*htab->free_with_arg_f) (htab->alloc_arg, oentries); | |
| 578 return 1; | |
| 579 } | |
| 580 | |
| 581 /* This function searches for a hash table entry equal to the given | |
| 582 element. It cannot be used to insert or delete an element. */ | |
| 583 | |
| 584 PTR | |
| 585 htab_find_with_hash (htab_t htab, const PTR element, hashval_t hash) | |
| 586 { | |
| 587 hashval_t index, hash2; | |
| 588 size_t size; | |
| 589 PTR entry; | |
| 590 | |
| 591 htab->searches++; | |
| 592 size = htab_size (htab); | |
| 593 index = htab_mod (hash, htab); | |
| 594 | |
| 595 entry = htab->entries[index]; | |
| 596 if (entry == HTAB_EMPTY_ENTRY | |
| 597 || (entry != HTAB_DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
| 598 return entry; | |
| 599 | |
| 600 hash2 = htab_mod_m2 (hash, htab); | |
| 601 for (;;) | |
| 602 { | |
| 603 htab->collisions++; | |
| 604 index += hash2; | |
| 605 if (index >= size) | |
| 606 index -= size; | |
| 607 | |
| 608 entry = htab->entries[index]; | |
| 609 if (entry == HTAB_EMPTY_ENTRY | |
| 610 || (entry != HTAB_DELETED_ENTRY && (*htab->eq_f) (entry, element))) | |
| 611 return entry; | |
| 612 } | |
| 613 } | |
| 614 | |
| 615 /* Like htab_find_slot_with_hash, but compute the hash value from the | |
| 616 element. */ | |
| 617 | |
| 618 PTR | |
| 619 htab_find (htab_t htab, const PTR element) | |
| 620 { | |
| 621 return htab_find_with_hash (htab, element, (*htab->hash_f) (element)); | |
| 622 } | |
| 623 | |
| 624 /* This function searches for a hash table slot containing an entry | |
| 625 equal to the given element. To delete an entry, call this with | |
| 626 insert=NO_INSERT, then call htab_clear_slot on the slot returned | |
| 627 (possibly after doing some checks). To insert an entry, call this | |
| 628 with insert=INSERT, then write the value you want into the returned | |
| 629 slot. When inserting an entry, NULL may be returned if memory | |
| 630 allocation fails. */ | |
| 631 | |
| 632 PTR * | |
| 633 htab_find_slot_with_hash (htab_t htab, const PTR element, | |
| 634 hashval_t hash, enum insert_option insert) | |
| 635 { | |
| 636 PTR *first_deleted_slot; | |
| 637 hashval_t index, hash2; | |
| 638 size_t size; | |
| 639 PTR entry; | |
| 640 | |
| 641 size = htab_size (htab); | |
| 642 if (insert == INSERT && size * 3 <= htab->n_elements * 4) | |
| 643 { | |
| 644 if (htab_expand (htab) == 0) | |
| 645 return NULL; | |
| 646 size = htab_size (htab); | |
| 647 } | |
| 648 | |
| 649 index = htab_mod (hash, htab); | |
| 650 | |
| 651 htab->searches++; | |
| 652 first_deleted_slot = NULL; | |
| 653 | |
| 654 entry = htab->entries[index]; | |
| 655 if (entry == HTAB_EMPTY_ENTRY) | |
| 656 goto empty_entry; | |
| 657 else if (entry == HTAB_DELETED_ENTRY) | |
| 658 first_deleted_slot = &htab->entries[index]; | |
| 659 else if ((*htab->eq_f) (entry, element)) | |
| 660 return &htab->entries[index]; | |
| 661 | |
| 662 hash2 = htab_mod_m2 (hash, htab); | |
| 663 for (;;) | |
| 664 { | |
| 665 htab->collisions++; | |
| 666 index += hash2; | |
| 667 if (index >= size) | |
| 668 index -= size; | |
| 669 | |
| 670 entry = htab->entries[index]; | |
| 671 if (entry == HTAB_EMPTY_ENTRY) | |
| 672 goto empty_entry; | |
| 673 else if (entry == HTAB_DELETED_ENTRY) | |
| 674 { | |
| 675 if (!first_deleted_slot) | |
| 676 first_deleted_slot = &htab->entries[index]; | |
| 677 } | |
| 678 else if ((*htab->eq_f) (entry, element)) | |
| 679 return &htab->entries[index]; | |
| 680 } | |
| 681 | |
| 682 empty_entry: | |
| 683 if (insert == NO_INSERT) | |
| 684 return NULL; | |
| 685 | |
| 686 if (first_deleted_slot) | |
| 687 { | |
| 688 htab->n_deleted--; | |
| 689 *first_deleted_slot = HTAB_EMPTY_ENTRY; | |
| 690 return first_deleted_slot; | |
| 691 } | |
| 692 | |
| 693 htab->n_elements++; | |
| 694 return &htab->entries[index]; | |
| 695 } | |
| 696 | |
| 697 /* Like htab_find_slot_with_hash, but compute the hash value from the | |
| 698 element. */ | |
| 699 | |
| 700 PTR * | |
| 701 htab_find_slot (htab_t htab, const PTR element, enum insert_option insert) | |
| 702 { | |
| 703 return htab_find_slot_with_hash (htab, element, (*htab->hash_f) (element), | |
| 704 insert); | |
| 705 } | |
| 706 | |
| 707 /* This function deletes an element with the given value from hash | |
| 708 table (the hash is computed from the element). If there is no matching | |
| 709 element in the hash table, this function does nothing. */ | |
| 710 | |
| 711 void | |
| 145 | 712 htab_remove_elt (htab_t htab, const PTR element) |
| 0 | 713 { |
| 714 htab_remove_elt_with_hash (htab, element, (*htab->hash_f) (element)); | |
| 715 } | |
| 716 | |
| 717 | |
| 718 /* This function deletes an element with the given value from hash | |
| 719 table. If there is no matching element in the hash table, this | |
| 720 function does nothing. */ | |
| 721 | |
| 722 void | |
| 145 | 723 htab_remove_elt_with_hash (htab_t htab, const PTR element, hashval_t hash) |
| 0 | 724 { |
| 725 PTR *slot; | |
| 726 | |
| 727 slot = htab_find_slot_with_hash (htab, element, hash, NO_INSERT); | |
| 145 | 728 if (slot == NULL) |
| 0 | 729 return; |
| 730 | |
| 731 if (htab->del_f) | |
| 732 (*htab->del_f) (*slot); | |
| 733 | |
| 734 *slot = HTAB_DELETED_ENTRY; | |
| 735 htab->n_deleted++; | |
| 736 } | |
| 737 | |
| 738 /* This function clears a specified slot in a hash table. It is | |
| 739 useful when you've already done the lookup and don't want to do it | |
| 740 again. */ | |
| 741 | |
| 742 void | |
| 743 htab_clear_slot (htab_t htab, PTR *slot) | |
| 744 { | |
| 745 if (slot < htab->entries || slot >= htab->entries + htab_size (htab) | |
| 746 || *slot == HTAB_EMPTY_ENTRY || *slot == HTAB_DELETED_ENTRY) | |
| 747 abort (); | |
| 748 | |
| 749 if (htab->del_f) | |
| 750 (*htab->del_f) (*slot); | |
| 751 | |
| 752 *slot = HTAB_DELETED_ENTRY; | |
| 753 htab->n_deleted++; | |
| 754 } | |
| 755 | |
| 756 /* This function scans over the entire hash table calling | |
| 757 CALLBACK for each live entry. If CALLBACK returns false, | |
| 758 the iteration stops. INFO is passed as CALLBACK's second | |
| 759 argument. */ | |
| 760 | |
| 761 void | |
| 762 htab_traverse_noresize (htab_t htab, htab_trav callback, PTR info) | |
| 763 { | |
| 764 PTR *slot; | |
| 765 PTR *limit; | |
| 766 | |
| 767 slot = htab->entries; | |
| 768 limit = slot + htab_size (htab); | |
| 769 | |
| 770 do | |
| 771 { | |
| 772 PTR x = *slot; | |
| 773 | |
| 774 if (x != HTAB_EMPTY_ENTRY && x != HTAB_DELETED_ENTRY) | |
| 775 if (!(*callback) (slot, info)) | |
| 776 break; | |
| 777 } | |
| 778 while (++slot < limit); | |
| 779 } | |
| 780 | |
| 781 /* Like htab_traverse_noresize, but does resize the table when it is | |
| 782 too empty to improve effectivity of subsequent calls. */ | |
| 783 | |
| 784 void | |
| 785 htab_traverse (htab_t htab, htab_trav callback, PTR info) | |
| 786 { | |
|
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787 size_t size = htab_size (htab); |
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|
788 if (htab_elements (htab) * 8 < size && size > 32) |
| 0 | 789 htab_expand (htab); |
| 790 | |
| 791 htab_traverse_noresize (htab, callback, info); | |
| 792 } | |
| 793 | |
| 794 /* Return the fraction of fixed collisions during all work with given | |
| 795 hash table. */ | |
| 796 | |
| 797 double | |
| 798 htab_collisions (htab_t htab) | |
| 799 { | |
| 800 if (htab->searches == 0) | |
| 801 return 0.0; | |
| 802 | |
| 803 return (double) htab->collisions / (double) htab->searches; | |
| 804 } | |
| 805 | |
| 806 /* Hash P as a null-terminated string. | |
| 807 | |
| 808 Copied from gcc/hashtable.c. Zack had the following to say with respect | |
| 809 to applicability, though note that unlike hashtable.c, this hash table | |
| 810 implementation re-hashes rather than chain buckets. | |
| 811 | |
| 812 http://gcc.gnu.org/ml/gcc-patches/2001-08/msg01021.html | |
| 813 From: Zack Weinberg <zackw@panix.com> | |
| 814 Date: Fri, 17 Aug 2001 02:15:56 -0400 | |
| 815 | |
| 816 I got it by extracting all the identifiers from all the source code | |
| 817 I had lying around in mid-1999, and testing many recurrences of | |
| 818 the form "H_n = H_{n-1} * K + c_n * L + M" where K, L, M were either | |
| 819 prime numbers or the appropriate identity. This was the best one. | |
| 820 I don't remember exactly what constituted "best", except I was | |
| 821 looking at bucket-length distributions mostly. | |
| 822 | |
| 823 So it should be very good at hashing identifiers, but might not be | |
| 824 as good at arbitrary strings. | |
| 825 | |
| 826 I'll add that it thoroughly trounces the hash functions recommended | |
| 827 for this use at http://burtleburtle.net/bob/hash/index.html, both | |
| 828 on speed and bucket distribution. I haven't tried it against the | |
| 829 function they just started using for Perl's hashes. */ | |
| 830 | |
| 831 hashval_t | |
| 832 htab_hash_string (const PTR p) | |
| 833 { | |
| 834 const unsigned char *str = (const unsigned char *) p; | |
| 835 hashval_t r = 0; | |
| 836 unsigned char c; | |
| 837 | |
| 838 while ((c = *str++) != 0) | |
| 839 r = r * 67 + c - 113; | |
| 840 | |
| 841 return r; | |
| 842 } | |
| 843 | |
| 844 /* DERIVED FROM: | |
| 845 -------------------------------------------------------------------- | |
| 846 lookup2.c, by Bob Jenkins, December 1996, Public Domain. | |
| 847 hash(), hash2(), hash3, and mix() are externally useful functions. | |
| 848 Routines to test the hash are included if SELF_TEST is defined. | |
| 849 You can use this free for any purpose. It has no warranty. | |
| 850 -------------------------------------------------------------------- | |
| 851 */ | |
| 852 | |
| 853 /* | |
| 854 -------------------------------------------------------------------- | |
| 855 mix -- mix 3 32-bit values reversibly. | |
| 856 For every delta with one or two bit set, and the deltas of all three | |
| 857 high bits or all three low bits, whether the original value of a,b,c | |
| 858 is almost all zero or is uniformly distributed, | |
| 859 * If mix() is run forward or backward, at least 32 bits in a,b,c | |
| 860 have at least 1/4 probability of changing. | |
| 861 * If mix() is run forward, every bit of c will change between 1/3 and | |
| 862 2/3 of the time. (Well, 22/100 and 78/100 for some 2-bit deltas.) | |
| 863 mix() was built out of 36 single-cycle latency instructions in a | |
| 864 structure that could supported 2x parallelism, like so: | |
| 865 a -= b; | |
| 866 a -= c; x = (c>>13); | |
| 867 b -= c; a ^= x; | |
| 868 b -= a; x = (a<<8); | |
| 869 c -= a; b ^= x; | |
| 870 c -= b; x = (b>>13); | |
| 871 ... | |
| 872 Unfortunately, superscalar Pentiums and Sparcs can't take advantage | |
| 873 of that parallelism. They've also turned some of those single-cycle | |
| 874 latency instructions into multi-cycle latency instructions. Still, | |
| 875 this is the fastest good hash I could find. There were about 2^^68 | |
| 876 to choose from. I only looked at a billion or so. | |
| 877 -------------------------------------------------------------------- | |
| 878 */ | |
| 879 /* same, but slower, works on systems that might have 8 byte hashval_t's */ | |
| 880 #define mix(a,b,c) \ | |
| 881 { \ | |
| 882 a -= b; a -= c; a ^= (c>>13); \ | |
| 883 b -= c; b -= a; b ^= (a<< 8); \ | |
| 884 c -= a; c -= b; c ^= ((b&0xffffffff)>>13); \ | |
| 885 a -= b; a -= c; a ^= ((c&0xffffffff)>>12); \ | |
| 886 b -= c; b -= a; b = (b ^ (a<<16)) & 0xffffffff; \ | |
| 887 c -= a; c -= b; c = (c ^ (b>> 5)) & 0xffffffff; \ | |
| 888 a -= b; a -= c; a = (a ^ (c>> 3)) & 0xffffffff; \ | |
| 889 b -= c; b -= a; b = (b ^ (a<<10)) & 0xffffffff; \ | |
| 890 c -= a; c -= b; c = (c ^ (b>>15)) & 0xffffffff; \ | |
| 891 } | |
| 892 | |
| 893 /* | |
| 894 -------------------------------------------------------------------- | |
| 895 hash() -- hash a variable-length key into a 32-bit value | |
| 896 k : the key (the unaligned variable-length array of bytes) | |
| 897 len : the length of the key, counting by bytes | |
| 898 level : can be any 4-byte value | |
| 899 Returns a 32-bit value. Every bit of the key affects every bit of | |
| 900 the return value. Every 1-bit and 2-bit delta achieves avalanche. | |
| 901 About 36+6len instructions. | |
| 902 | |
| 903 The best hash table sizes are powers of 2. There is no need to do | |
| 904 mod a prime (mod is sooo slow!). If you need less than 32 bits, | |
| 905 use a bitmask. For example, if you need only 10 bits, do | |
| 906 h = (h & hashmask(10)); | |
| 907 In which case, the hash table should have hashsize(10) elements. | |
| 908 | |
| 909 If you are hashing n strings (ub1 **)k, do it like this: | |
| 910 for (i=0, h=0; i<n; ++i) h = hash( k[i], len[i], h); | |
| 911 | |
| 912 By Bob Jenkins, 1996. bob_jenkins@burtleburtle.net. You may use this | |
| 913 code any way you wish, private, educational, or commercial. It's free. | |
| 914 | |
| 915 See http://burtleburtle.net/bob/hash/evahash.html | |
| 916 Use for hash table lookup, or anything where one collision in 2^32 is | |
| 917 acceptable. Do NOT use for cryptographic purposes. | |
| 918 -------------------------------------------------------------------- | |
| 919 */ | |
| 920 | |
| 921 hashval_t | |
| 922 iterative_hash (const PTR k_in /* the key */, | |
| 923 register size_t length /* the length of the key */, | |
| 924 register hashval_t initval /* the previous hash, or | |
| 925 an arbitrary value */) | |
| 926 { | |
| 927 register const unsigned char *k = (const unsigned char *)k_in; | |
| 928 register hashval_t a,b,c,len; | |
| 929 | |
| 930 /* Set up the internal state */ | |
| 931 len = length; | |
| 932 a = b = 0x9e3779b9; /* the golden ratio; an arbitrary value */ | |
| 933 c = initval; /* the previous hash value */ | |
| 934 | |
| 935 /*---------------------------------------- handle most of the key */ | |
| 936 #ifndef WORDS_BIGENDIAN | |
| 937 /* On a little-endian machine, if the data is 4-byte aligned we can hash | |
| 938 by word for better speed. This gives nondeterministic results on | |
| 939 big-endian machines. */ | |
| 940 if (sizeof (hashval_t) == 4 && (((size_t)k)&3) == 0) | |
| 941 while (len >= 12) /* aligned */ | |
| 942 { | |
| 943 a += *(hashval_t *)(k+0); | |
| 944 b += *(hashval_t *)(k+4); | |
| 945 c += *(hashval_t *)(k+8); | |
| 946 mix(a,b,c); | |
| 947 k += 12; len -= 12; | |
| 948 } | |
| 949 else /* unaligned */ | |
| 950 #endif | |
| 951 while (len >= 12) | |
| 952 { | |
| 953 a += (k[0] +((hashval_t)k[1]<<8) +((hashval_t)k[2]<<16) +((hashval_t)k[3]<<24)); | |
| 954 b += (k[4] +((hashval_t)k[5]<<8) +((hashval_t)k[6]<<16) +((hashval_t)k[7]<<24)); | |
| 955 c += (k[8] +((hashval_t)k[9]<<8) +((hashval_t)k[10]<<16)+((hashval_t)k[11]<<24)); | |
| 956 mix(a,b,c); | |
| 957 k += 12; len -= 12; | |
| 958 } | |
| 959 | |
| 960 /*------------------------------------- handle the last 11 bytes */ | |
| 961 c += length; | |
| 962 switch(len) /* all the case statements fall through */ | |
| 963 { | |
| 111 | 964 case 11: c+=((hashval_t)k[10]<<24); /* fall through */ |
| 965 case 10: c+=((hashval_t)k[9]<<16); /* fall through */ | |
| 966 case 9 : c+=((hashval_t)k[8]<<8); /* fall through */ | |
| 0 | 967 /* the first byte of c is reserved for the length */ |
| 111 | 968 case 8 : b+=((hashval_t)k[7]<<24); /* fall through */ |
| 969 case 7 : b+=((hashval_t)k[6]<<16); /* fall through */ | |
| 970 case 6 : b+=((hashval_t)k[5]<<8); /* fall through */ | |
| 971 case 5 : b+=k[4]; /* fall through */ | |
| 972 case 4 : a+=((hashval_t)k[3]<<24); /* fall through */ | |
| 973 case 3 : a+=((hashval_t)k[2]<<16); /* fall through */ | |
| 974 case 2 : a+=((hashval_t)k[1]<<8); /* fall through */ | |
| 0 | 975 case 1 : a+=k[0]; |
| 976 /* case 0: nothing left to add */ | |
| 977 } | |
| 978 mix(a,b,c); | |
| 979 /*-------------------------------------------- report the result */ | |
| 980 return c; | |
| 981 } | |
| 111 | 982 |
| 983 /* Returns a hash code for pointer P. Simplified version of evahash */ | |
| 984 | |
| 985 static hashval_t | |
| 986 hash_pointer (const PTR p) | |
| 987 { | |
| 988 intptr_t v = (intptr_t) p; | |
| 989 unsigned a, b, c; | |
| 990 | |
| 991 a = b = 0x9e3779b9; | |
| 992 a += v >> (sizeof (intptr_t) * CHAR_BIT / 2); | |
| 993 b += v & (((intptr_t) 1 << (sizeof (intptr_t) * CHAR_BIT / 2)) - 1); | |
| 994 c = 0x42135234; | |
| 995 mix (a, b, c); | |
| 996 return c; | |
| 997 } |