-/*-
- * Copyright (c) 2015 Nuxi, https://nuxi.nl/
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. 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.
- *
- * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
- */
-
-#include <sys/cdefs.h>
-//__FBSDID("$FreeBSD$");
-
-#include <errno.h>
-#include <limits.h>
-#include "search.h"
-#include <stdint.h>
-#include <stdlib.h>
-#include <string.h>
-
-#include "hsearch.h"
-
-/*
- * Look up an unused entry in the hash table for a given hash. For this
- * implementation we use quadratic probing. Quadratic probing has the
- * advantage of preventing primary clustering.
- */
-static ENTRY *
-hsearch_lookup_free(struct __hsearch *hsearch, size_t hash)
-{
- size_t index, i;
-
- for (index = hash, i = 0;; index += ++i) {
- ENTRY *entry = &hsearch->entries[index & hsearch->index_mask];
- if (entry->key == NULL)
- return (entry);
- }
-}
-
-/*
- * Computes an FNV-1a hash of the key. Depending on the pointer size, this
- * either uses the 32- or 64-bit FNV prime.
- */
-static size_t
-hsearch_hash(size_t offset_basis, const char *str)
-{
- size_t hash;
-
- hash = offset_basis;
- while (*str != '\0') {
- hash ^= (uint8_t)*str++;
- if (sizeof(size_t) * CHAR_BIT <= 32)
- hash *= UINT32_C(16777619);
- else
- hash *= UINT64_C(1099511628211);
- }
- return (hash);
-}
-
-int
-hsearch_r(ENTRY item, ACTION action, ENTRY **retval, struct hsearch_data *htab)
-{
- struct __hsearch *hsearch;
- ENTRY *entry, *old_entries, *new_entries;
- size_t hash, index, i, old_hash, old_count, new_count;
-
- hsearch = htab->__hsearch;
- hash = hsearch_hash(hsearch->offset_basis, item.key);
-
- /*
- * Search the hash table for an existing entry for this key.
- * Stop searching if we run into an unused hash table entry.
- */
- for (index = hash, i = 0;; index += ++i) {
- entry = &hsearch->entries[index & hsearch->index_mask];
- if (entry->key == NULL)
- break;
- if (strcmp(entry->key, item.key) == 0) {
- *retval = entry;
- return (1);
- }
- }
-
- /* Only perform the insertion if action is set to ENTER. */
- if (action == FIND) {
- errno = ESRCH;
- return (0);
- }
-
- if (hsearch->entries_used * 2 >= hsearch->index_mask) {
- /* Preserve the old hash table entries. */
- old_count = hsearch->index_mask + 1;
- old_entries = hsearch->entries;
-
- /*
- * Allocate and install a new table if insertion would
- * yield a hash table that is more than 50% used. By
- * using 50% as a threshold, a lookup will only take up
- * to two steps on average.
- */
- new_count = (hsearch->index_mask + 1) * 2;
- new_entries = calloc(new_count, sizeof(ENTRY));
- if (new_entries == NULL)
- return (0);
- hsearch->entries = new_entries;
- hsearch->index_mask = new_count - 1;
-
- /* Copy over the entries from the old table to the new table. */
- for (i = 0; i < old_count; ++i) {
- entry = &old_entries[i];
- if (entry->key != NULL) {
- old_hash = hsearch_hash(hsearch->offset_basis,
- entry->key);
- *hsearch_lookup_free(hsearch, old_hash) =
- *entry;
- }
- }
-
- /* Destroy the old hash table entries. */
- free(old_entries);
-
- /*
- * Perform a new lookup for a free table entry, so that
- * we insert the entry into the new hash table.
- */
- hsearch = htab->__hsearch;
- entry = hsearch_lookup_free(hsearch, hash);
- }
-
- /* Insert the new entry into the hash table. */
- *entry = item;
- ++hsearch->entries_used;
- *retval = entry;
- return (1);
-}
~mdw / termux-packages / commitdiff