From 3ef6719f47b734b12c0b11c725b7f12e3fb3c08a Mon Sep 17 00:00:00 2001 From: Uros Majstorovic Date: Tue, 23 May 2017 14:19:26 +0200 Subject: fs layout updated --- code/core/htable/hashtable.c | 263 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 263 insertions(+) create mode 100755 code/core/htable/hashtable.c (limited to 'code/core/htable/hashtable.c') diff --git a/code/core/htable/hashtable.c b/code/core/htable/hashtable.c new file mode 100755 index 0000000..8174a5d --- /dev/null +++ b/code/core/htable/hashtable.c @@ -0,0 +1,263 @@ +/* Copyright (C) 2004 Christopher Clark */ + +#include "hashtable.h" +#include "hashtable_private.h" +#include +#include +#include + +/* +Credit for primes table: Aaron Krowne + http://br.endernet.org/~akrowne/ + http://planetmath.org/encyclopedia/GoodHashTablePrimes.html +*/ +static const unsigned int primes[] = { +53, 97, 193, 389, +769, 1543, 3079, 6151, +12289, 24593, 49157, 98317, +196613, 393241, 786433, 1572869, +3145739, 6291469, 12582917, 25165843, +50331653, 100663319, 201326611, 402653189, +805306457, 1610612741 +}; +const unsigned int prime_table_length = sizeof(primes)/sizeof(primes[0]); +const float max_load_factor = 0.65; + +/*****************************************************************************/ +int +create_hashtable(struct hashtable *h, unsigned int minsize, + unsigned int (*hash_fn) (void*), + int (*eq_fn) (void*,void*), + void *(*malloc_fn) (size_t), + void *(*realloc_fn) (void*,size_t), + void (*free_fn) (void*)) +{ + unsigned int pindex, size = primes[0]; + /* Check requested hashtable isn't too large */ + if (minsize > (1u << 30)) return 0; + /* Enforce size as prime */ + for (pindex=0; pindex < prime_table_length; pindex++) { + if (primes[pindex] > minsize) { size = primes[pindex]; break; } + } + h->fn_malloc = malloc_fn ? malloc_fn : malloc; + h->fn_realloc = realloc_fn ? realloc_fn : realloc; + h->fn_free = free_fn ? free_fn : free; + h->tablelength = size; + h->primeindex = pindex; + h->entrycount = 0; + h->fn_hash = hash_fn; + h->fn_eq = eq_fn; + h->loadlimit = (unsigned int) ceil(size * max_load_factor); + h->table = h->fn_malloc(sizeof(struct entry *) * size); + if (NULL == h->table) return 0; /*oom*/ + memset(h->table, 0, size * sizeof(struct entry *)); + return -1; +} + +/*****************************************************************************/ +unsigned int +hashtable_hash(struct hashtable *h, void *k) +{ + /* Aim to protect against poor hash functions by adding logic here + * - logic taken from java 1.4 hashtable source */ + unsigned int i = h->fn_hash(k); + i += ~(i << 9); + i ^= ((i >> 14) | (i << 18)); /* >>> */ + i += (i << 4); + i ^= ((i >> 10) | (i << 22)); /* >>> */ + return i; +} + +/*****************************************************************************/ +static int +hashtable_expand(struct hashtable *h) +{ + /* Double the size of the table to accomodate more entries */ + struct entry **newtable; + struct entry *e; + struct entry **pE; + unsigned int newsize, i, index; + /* Check we're not hitting max capacity */ + if (h->primeindex == (prime_table_length - 1)) return 0; + newsize = primes[++(h->primeindex)]; + + newtable = h->fn_malloc(sizeof(struct entry *) * newsize); + if (NULL != newtable) + { + memset(newtable, 0, newsize * sizeof(struct entry *)); + /* This algorithm is not 'stable'. ie. it reverses the list + * when it transfers entries between the tables */ + for (i = 0; i < h->tablelength; i++) { + while (NULL != (e = h->table[i])) { + h->table[i] = e->next; + index = indexFor(newsize,e->h); + e->next = newtable[index]; + newtable[index] = e; + } + } + h->fn_free(h->table); + h->table = newtable; + } + /* Plan B: realloc instead */ + else + { + newtable = h->fn_realloc(h->table, newsize * sizeof(struct entry *)); + if (NULL == newtable) { (h->primeindex)--; return 0; } + h->table = newtable; + memset(newtable[h->tablelength], 0, newsize - h->tablelength); + for (i = 0; i < h->tablelength; i++) { + for (pE = &(newtable[i]), e = *pE; e != NULL; e = *pE) { + index = indexFor(newsize,e->h); + if (index == i) + { + pE = &(e->next); + } + else + { + *pE = e->next; + e->next = newtable[index]; + newtable[index] = e; + } + } + } + } + h->tablelength = newsize; + h->loadlimit = (unsigned int) ceil(newsize * max_load_factor); + return -1; +} + +/*****************************************************************************/ +unsigned int +hashtable_count(struct hashtable *h) +{ + return h->entrycount; +} + +/*****************************************************************************/ +int +hashtable_insert(struct hashtable *h, void *k, void *v) +{ + /* This method allows duplicate keys - but they shouldn't be used */ + unsigned int index; + struct entry *e; + if (++(h->entrycount) > h->loadlimit) + { + /* Ignore the return value. If expand fails, we should + * still try cramming just this value into the existing table + * -- we may not have memory for a larger table, but one more + * element may be ok. Next time we insert, we'll try expanding again.*/ + hashtable_expand(h); + } + e = h->fn_malloc(sizeof(struct entry)); + if (NULL == e) { --(h->entrycount); return 0; } /*oom*/ + e->h = hashtable_hash(h,k); + index = indexFor(h->tablelength,e->h); + e->k = k; + e->v = v; + e->next = h->table[index]; + h->table[index] = e; + return -1; +} + +/*****************************************************************************/ +void * /* returns value associated with key */ +hashtable_search(struct hashtable *h, void *k) +{ + struct entry *e; + unsigned int hashvalue, index; + hashvalue = hashtable_hash(h,k); + index = indexFor(h->tablelength,hashvalue); + e = h->table[index]; + while (NULL != e) + { + /* Check hash value to short circuit heavier comparison */ + if ((hashvalue == e->h) && (h->fn_eq(k, e->k))) return e->v; + e = e->next; + } + return NULL; +} + +/*****************************************************************************/ +void * /* returns value associated with key --- modified by majstor */ +hashtable_remove(struct hashtable *h, void *k) +{ + /* TODO: consider compacting the table when the load factor drops enough, + * or provide a 'compact' method. */ + + struct entry *e; + struct entry **pE; + void *v; + unsigned int hashvalue, index; + + hashvalue = hashtable_hash(h,k); + index = indexFor(h->tablelength,hashtable_hash(h,k)); + pE = &(h->table[index]); + e = *pE; + while (NULL != e) + { + /* Check hash value to short circuit heavier comparison */ + if ((hashvalue == e->h) && (h->fn_eq(k, e->k))) + { + *pE = e->next; + h->entrycount--; + v = e->v; + if (h->fn_free_k) h->fn_free_k(e->k); + h->fn_free(e); + return v; + } + pE = &(e->next); + e = e->next; + } + return NULL; +} + +/*****************************************************************************/ +/* destroy --- modified by majstor */ +void +hashtable_destroy(struct hashtable *h) +{ + unsigned int i; + struct entry *e, *f; + struct entry **table = h->table; + + for (i = 0; i < h->tablelength; i++) + { + e = table[i]; + while (NULL != e) + { f = e; e = e->next; if (h->fn_free_k) h->fn_free_k(f->k); if (h->fn_free_v) h->fn_free_v(f->v); h->fn_free(f); } + } + h->fn_free(h->table); +} + +/* + * Copyright (c) 2002, Christopher Clark + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * * Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * * Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * * Neither the name of the original author; nor the names of any contributors + * may be used to endorse or promote products derived from this software + * without specific prior written permission. + * + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR + * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER + * OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, + * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, + * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR + * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF + * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING + * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS + * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +*/ -- cgit v1.2.3