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Diffstat (limited to 'lib/fixedsizehash.h')
| -rw-r--r-- | lib/fixedsizehash.h | 267 |
1 files changed, 267 insertions, 0 deletions
diff --git a/lib/fixedsizehash.h b/lib/fixedsizehash.h new file mode 100644 index 00000000..06ce6a25 --- /dev/null +++ b/lib/fixedsizehash.h @@ -0,0 +1,267 @@ +/* Fixed size hash table with internal linking. + Copyright (C) 2000, 2001, 2002, 2004, 2005 Red Hat, Inc. + This file is part of elfutils. + Written by Ulrich Drepper <drepper@redhat.com>, 2000. + + This file is free software; you can redistribute it and/or modify + it under the terms of either + + * the GNU Lesser General Public License as published by the Free + Software Foundation; either version 3 of the License, or (at + your option) any later version + + or + + * the GNU General Public License as published by the Free + Software Foundation; either version 2 of the License, or (at + your option) any later version + + or both in parallel, as here. + + elfutils 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 + General Public License for more details. + + You should have received copies of the GNU General Public License and + the GNU Lesser General Public License along with this program. If + not, see <http://www.gnu.org/licenses/>. */ + +#include <errno.h> +#include <stdlib.h> +#include <string.h> +#include <sys/cdefs.h> +#include <sys/param.h> + +#include <system.h> + +#define CONCAT(t1,t2) __CONCAT (t1,t2) + +/* Before including this file the following macros must be defined: + + TYPE data type of the hash table entries + HASHFCT name of the hashing function to use + HASHTYPE type used for the hashing value + COMPARE comparison function taking two pointers to TYPE objects + CLASS can be defined to `static' to avoid exporting the functions + PREFIX prefix to be used for function and data type names + STORE_POINTER if defined the table stores a pointer and not an element + of type TYPE + INSERT_HASH if defined alternate insert function which takes a hash + value is defined + NO_FINI_FCT if defined the fini function is not defined +*/ + + +/* Defined separately. */ +extern size_t next_prime (size_t seed); + + +/* Set default values. */ +#ifndef HASHTYPE +# define HASHTYPE size_t +#endif + +#ifndef CLASS +# define CLASS +#endif + +#ifndef PREFIX +# define PREFIX +#endif + + +/* The data structure. */ +struct CONCAT(PREFIX,fshash) +{ + size_t nslots; + struct CONCAT(PREFIX,fshashent) + { + HASHTYPE hval; +#ifdef STORE_POINTER +# define ENTRYP(el) (el).entry + TYPE *entry; +#else +# define ENTRYP(el) &(el).entry + TYPE entry; +#endif + } table[0]; +}; + + +/* Constructor for the hashing table. */ +CLASS struct CONCAT(PREFIX,fshash) * +CONCAT(PREFIX,fshash_init) (size_t nelems) +{ + struct CONCAT(PREFIX,fshash) *result; + /* We choose a size for the hashing table 150% over the number of + entries. This will guarantee short medium search lengths. */ + const size_t max_size_t = ~((size_t) 0); + + if (nelems >= (max_size_t / 3) * 2) + { + errno = EINVAL; + return NULL; + } + + /* Adjust the size to be used for the hashing table. */ + nelems = next_prime (MAX ((nelems * 3) / 2, 10)); + + /* Allocate the data structure for the result. */ + result = (struct CONCAT(PREFIX,fshash) *) + xcalloc (sizeof (struct CONCAT(PREFIX,fshash)) + + (nelems + 1) * sizeof (struct CONCAT(PREFIX,fshashent)), 1); + if (result == NULL) + return NULL; + + result->nslots = nelems; + + return result; +} + + +#ifndef NO_FINI_FCT +CLASS void +CONCAT(PREFIX,fshash_fini) (struct CONCAT(PREFIX,fshash) *htab) +{ + free (htab); +} +#endif + + +static struct CONCAT(PREFIX,fshashent) * +CONCAT(PREFIX,fshash_lookup) (struct CONCAT(PREFIX,fshash) *htab, + HASHTYPE hval, TYPE *data) +{ + size_t idx = 1 + hval % htab->nslots; + + if (htab->table[idx].hval != 0) + { + HASHTYPE hash; + + /* See whether this is the same entry. */ + if (htab->table[idx].hval == hval + && COMPARE (data, ENTRYP (htab->table[idx])) == 0) + return &htab->table[idx]; + + /* Second hash function as suggested in [Knuth]. */ + hash = 1 + hval % (htab->nslots - 2); + + do + { + if (idx <= hash) + idx = htab->nslots + idx - hash; + else + idx -= hash; + + if (htab->table[idx].hval == hval + && COMPARE (data, ENTRYP(htab->table[idx])) == 0) + return &htab->table[idx]; + } + while (htab->table[idx].hval != 0); + } + + return &htab->table[idx]; +} + + +CLASS int +__attribute__ ((unused)) +CONCAT(PREFIX,fshash_insert) (struct CONCAT(PREFIX,fshash) *htab, + const char *str, + size_t len __attribute__ ((unused)), TYPE *data) +{ + HASHTYPE hval = HASHFCT (str, len ?: strlen (str)); + struct CONCAT(PREFIX,fshashent) *slot; + + slot = CONCAT(PREFIX,fshash_lookup) (htab, hval, data); + if (slot->hval != 0) + /* We don't want to overwrite the old value. */ + return -1; + + slot->hval = hval; +#ifdef STORE_POINTER + slot->entry = data; +#else + slot->entry = *data; +#endif + + return 0; +} + + +#ifdef INSERT_HASH +CLASS int +__attribute__ ((unused)) +CONCAT(PREFIX,fshash_insert_hash) (struct CONCAT(PREFIX,fshash) *htab, + HASHTYPE hval, TYPE *data) +{ + struct CONCAT(PREFIX,fshashent) *slot; + + slot = CONCAT(PREFIX,fshash_lookup) (htab, hval, data); + if (slot->hval != 0) + /* We don't want to overwrite the old value. */ + return -1; + + slot->hval = hval; +#ifdef STORE_POINTER + slot->entry = data; +#else + slot->entry = *data; +#endif + + return 0; +} +#endif + + +CLASS int +__attribute__ ((unused)) +CONCAT(PREFIX,fshash_overwrite) (struct CONCAT(PREFIX,fshash) *htab, + const char *str, + size_t len __attribute__ ((unused)), + TYPE *data) +{ + HASHTYPE hval = HASHFCT (str, len ?: strlen (str)); + struct CONCAT(PREFIX,fshashent) *slot; + + slot = CONCAT(PREFIX,fshash_lookup) (htab, hval, data); + slot->hval = hval; +#ifdef STORE_POINTER + slot->entry = data; +#else + slot->entry = *data; +#endif + + return 0; +} + + +CLASS const TYPE * +CONCAT(PREFIX,fshash_find) (const struct CONCAT(PREFIX,fshash) *htab, + const char *str, + size_t len __attribute__ ((unused)), TYPE *data) +{ + HASHTYPE hval = HASHFCT (str, len ?: strlen (str)); + struct CONCAT(PREFIX,fshashent) *slot; + + slot = CONCAT(PREFIX,fshash_lookup) ((struct CONCAT(PREFIX,fshash) *) htab, + hval, data); + if (slot->hval == 0) + /* Not found. */ + return NULL; + + return ENTRYP(*slot); +} + + +/* Unset the macros we expect. */ +#undef TYPE +#undef HASHFCT +#undef HASHTYPE +#undef COMPARE +#undef CLASS +#undef PREFIX +#undef INSERT_HASH +#undef STORE_POINTER +#undef NO_FINI_FCT |