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Diffstat (limited to 'pjlib/src/pj/hash.c')
-rw-r--r-- | pjlib/src/pj/hash.c | 349 |
1 files changed, 349 insertions, 0 deletions
diff --git a/pjlib/src/pj/hash.c b/pjlib/src/pj/hash.c new file mode 100644 index 0000000..00f167f --- /dev/null +++ b/pjlib/src/pj/hash.c @@ -0,0 +1,349 @@ +/* $Id: hash.c 3553 2011-05-05 06:14:19Z nanang $ */ +/* + * Copyright (C) 2008-2011 Teluu Inc. (http://www.teluu.com) + * Copyright (C) 2003-2008 Benny Prijono <benny@prijono.org> + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of 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. + * + * This program 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 a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA + */ +#include <pj/hash.h> +#include <pj/log.h> +#include <pj/string.h> +#include <pj/pool.h> +#include <pj/os.h> +#include <pj/ctype.h> +#include <pj/assert.h> + +/** + * The hash multiplier used to calculate hash value. + */ +#define PJ_HASH_MULTIPLIER 33 + + +struct pj_hash_entry +{ + struct pj_hash_entry *next; + void *key; + pj_uint32_t hash; + pj_uint32_t keylen; + void *value; +}; + + +struct pj_hash_table_t +{ + pj_hash_entry **table; + unsigned count, rows; + pj_hash_iterator_t iterator; +}; + + + +PJ_DEF(pj_uint32_t) pj_hash_calc(pj_uint32_t hash, const void *key, + unsigned keylen) +{ + PJ_CHECK_STACK(); + + if (keylen==PJ_HASH_KEY_STRING) { + const pj_uint8_t *p = (const pj_uint8_t*)key; + for ( ; *p; ++p ) { + hash = (hash * PJ_HASH_MULTIPLIER) + *p; + } + } else { + const pj_uint8_t *p = (const pj_uint8_t*)key, + *end = p + keylen; + for ( ; p!=end; ++p) { + hash = (hash * PJ_HASH_MULTIPLIER) + *p; + } + } + return hash; +} + +PJ_DEF(pj_uint32_t) pj_hash_calc_tolower( pj_uint32_t hval, + char *result, + const pj_str_t *key) +{ + long i; + +#if defined(PJ_HASH_USE_OWN_TOLOWER) && PJ_HASH_USE_OWN_TOLOWER != 0 + for (i=0; i<key->slen; ++i) { + pj_uint8_t c = key->ptr[i]; + if (c & 64) + result[i] = (char)(c | 32); + else + result[i] = (char)c; + hval = hval * PJ_HASH_MULTIPLIER + result[i]; + } +#else + for (i=0; i<key->slen; ++i) { + result[i] = (char)pj_tolower(key->ptr[i]); + hval = hval * PJ_HASH_MULTIPLIER + result[i]; + } +#endif + + return hval; +} + + +PJ_DEF(pj_hash_table_t*) pj_hash_create(pj_pool_t *pool, unsigned size) +{ + pj_hash_table_t *h; + unsigned table_size; + + /* Check that PJ_HASH_ENTRY_BUF_SIZE is correct. */ + PJ_ASSERT_RETURN(sizeof(pj_hash_entry)<=PJ_HASH_ENTRY_BUF_SIZE, NULL); + + h = PJ_POOL_ALLOC_T(pool, pj_hash_table_t); + h->count = 0; + + PJ_LOG( 6, ("hashtbl", "hash table %p created from pool %s", h, pj_pool_getobjname(pool))); + + /* size must be 2^n - 1. + round-up the size to this rule, except when size is 2^n, then size + will be round-down to 2^n-1. + */ + table_size = 8; + do { + table_size <<= 1; + } while (table_size < size); + table_size -= 1; + + h->rows = table_size; + h->table = (pj_hash_entry**) + pj_pool_calloc(pool, table_size+1, sizeof(pj_hash_entry*)); + return h; +} + +static pj_hash_entry **find_entry( pj_pool_t *pool, pj_hash_table_t *ht, + const void *key, unsigned keylen, + void *val, pj_uint32_t *hval, + void *entry_buf) +{ + pj_uint32_t hash; + pj_hash_entry **p_entry, *entry; + + if (hval && *hval != 0) { + hash = *hval; + if (keylen==PJ_HASH_KEY_STRING) { + keylen = pj_ansi_strlen((const char*)key); + } + } else { + /* This slightly differs with pj_hash_calc() because we need + * to get the keylen when keylen is PJ_HASH_KEY_STRING. + */ + hash=0; + if (keylen==PJ_HASH_KEY_STRING) { + const pj_uint8_t *p = (const pj_uint8_t*)key; + for ( ; *p; ++p ) { + hash = hash * PJ_HASH_MULTIPLIER + *p; + } + keylen = p - (const unsigned char*)key; + } else { + const pj_uint8_t *p = (const pj_uint8_t*)key, + *end = p + keylen; + for ( ; p!=end; ++p) { + hash = hash * PJ_HASH_MULTIPLIER + *p; + } + } + + /* Report back the computed hash. */ + if (hval) + *hval = hash; + } + + /* scan the linked list */ + for (p_entry = &ht->table[hash & ht->rows], entry=*p_entry; + entry; + p_entry = &entry->next, entry = *p_entry) + { + if (entry->hash==hash && entry->keylen==keylen && + pj_memcmp(entry->key, key, keylen)==0) + { + break; + } + } + + if (entry || val==NULL) + return p_entry; + + /* Entry not found, create a new one. + * If entry_buf is specified, use it. Otherwise allocate from pool. + */ + if (entry_buf) { + entry = (pj_hash_entry*)entry_buf; + } else { + /* Pool must be specified! */ + PJ_ASSERT_RETURN(pool != NULL, NULL); + + entry = PJ_POOL_ALLOC_T(pool, pj_hash_entry); + PJ_LOG(6, ("hashtbl", + "%p: New p_entry %p created, pool used=%u, cap=%u", + ht, entry, pj_pool_get_used_size(pool), + pj_pool_get_capacity(pool))); + } + entry->next = NULL; + entry->hash = hash; + if (pool) { + entry->key = pj_pool_alloc(pool, keylen); + pj_memcpy(entry->key, key, keylen); + } else { + entry->key = (void*)key; + } + entry->keylen = keylen; + entry->value = val; + *p_entry = entry; + + ++ht->count; + + return p_entry; +} + +PJ_DEF(void *) pj_hash_get( pj_hash_table_t *ht, + const void *key, unsigned keylen, + pj_uint32_t *hval) +{ + pj_hash_entry *entry; + entry = *find_entry( NULL, ht, key, keylen, NULL, hval, NULL); + return entry ? entry->value : NULL; +} + +PJ_DEF(void) pj_hash_set( pj_pool_t *pool, pj_hash_table_t *ht, + const void *key, unsigned keylen, pj_uint32_t hval, + void *value ) +{ + pj_hash_entry **p_entry; + + p_entry = find_entry( pool, ht, key, keylen, value, &hval, NULL); + if (*p_entry) { + if (value == NULL) { + /* delete entry */ + PJ_LOG(6, ("hashtbl", "%p: p_entry %p deleted", ht, *p_entry)); + *p_entry = (*p_entry)->next; + --ht->count; + + } else { + /* overwrite */ + (*p_entry)->value = value; + PJ_LOG(6, ("hashtbl", "%p: p_entry %p value set to %p", ht, + *p_entry, value)); + } + } +} + +PJ_DEF(void) pj_hash_set_np( pj_hash_table_t *ht, + const void *key, unsigned keylen, + pj_uint32_t hval, pj_hash_entry_buf entry_buf, + void *value) +{ + pj_hash_entry **p_entry; + + p_entry = find_entry( NULL, ht, key, keylen, value, &hval, + (void*)entry_buf ); + if (*p_entry) { + if (value == NULL) { + /* delete entry */ + PJ_LOG(6, ("hashtbl", "%p: p_entry %p deleted", ht, *p_entry)); + *p_entry = (*p_entry)->next; + --ht->count; + + } else { + /* overwrite */ + (*p_entry)->value = value; + PJ_LOG(6, ("hashtbl", "%p: p_entry %p value set to %p", ht, + *p_entry, value)); + } + } +} + +PJ_DEF(unsigned) pj_hash_count( pj_hash_table_t *ht ) +{ + return ht->count; +} + +PJ_DEF(pj_hash_iterator_t*) pj_hash_first( pj_hash_table_t *ht, + pj_hash_iterator_t *it ) +{ + it->index = 0; + it->entry = NULL; + + for (; it->index <= ht->rows; ++it->index) { + it->entry = ht->table[it->index]; + if (it->entry) { + break; + } + } + + return it->entry ? it : NULL; +} + +PJ_DEF(pj_hash_iterator_t*) pj_hash_next( pj_hash_table_t *ht, + pj_hash_iterator_t *it ) +{ + it->entry = it->entry->next; + if (it->entry) { + return it; + } + + for (++it->index; it->index <= ht->rows; ++it->index) { + it->entry = ht->table[it->index]; + if (it->entry) { + break; + } + } + + return it->entry ? it : NULL; +} + +PJ_DEF(void*) pj_hash_this( pj_hash_table_t *ht, pj_hash_iterator_t *it ) +{ + PJ_CHECK_STACK(); + PJ_UNUSED_ARG(ht); + return it->entry->value; +} + +#if 0 +void pj_hash_dump_collision( pj_hash_table_t *ht ) +{ + unsigned min=0xFFFFFFFF, max=0; + unsigned i; + char line[120]; + int len, totlen = 0; + + for (i=0; i<=ht->rows; ++i) { + unsigned count = 0; + pj_hash_entry *entry = ht->table[i]; + while (entry) { + ++count; + entry = entry->next; + } + if (count < min) + min = count; + if (count > max) + max = count; + len = pj_snprintf( line+totlen, sizeof(line)-totlen, "%3d:%3d ", i, count); + if (len < 1) + break; + totlen += len; + + if ((i+1) % 10 == 0) { + line[totlen] = '\0'; + PJ_LOG(4,(__FILE__, line)); + } + } + + PJ_LOG(4,(__FILE__,"Count: %d, min: %d, max: %d\n", ht->count, min, max)); +} +#endif + + |