/* $OpenBSD: hcreate.c,v 1.7 2016/05/29 20:47:49 guenther Exp $ */ /* $NetBSD: hcreate.c,v 1.5 2004/04/23 02:48:12 simonb Exp $ */ /* * Copyright (c) 2001 Christopher G. Demetriou * All rights reserved. * * 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. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed for the * NetBSD Project. See http://www.NetBSD.org/ for * information about NetBSD. * 4. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 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. * * <> */ /* * hcreate() / hsearch() / hdestroy() * * SysV/XPG4 hash table functions. * * Implementation done based on NetBSD manual page and Solaris manual page, * plus my own personal experience about how they're supposed to work. * * I tried to look at Knuth (as cited by the Solaris manual page), but * nobody had a copy in the office, so... */ #include #include #include #include #include #include #include #include /* for __default_hash */ #ifndef _DIAGASSERT #define _DIAGASSERT(x) #endif /* * DO NOT MAKE THIS STRUCTURE LARGER THAN 32 BYTES (4 ptrs on 64-bit * ptr machine) without adjusting MAX_BUCKETS_LG2 below. */ struct internal_entry { SLIST_ENTRY(internal_entry) link; ENTRY ent; }; SLIST_HEAD(internal_head, internal_entry); #define MIN_BUCKETS_LG2 4 #define MIN_BUCKETS (1 << MIN_BUCKETS_LG2) /* * max * sizeof internal_entry must fit into size_t. * assumes internal_entry is <= 32 (2^5) bytes. */ #define MAX_BUCKETS_LG2 (sizeof (size_t) * 8 - 1 - 5) #define MAX_BUCKETS ((size_t)1 << MAX_BUCKETS_LG2) static struct internal_head *htable; static size_t htablesize; int hcreate(size_t nel) { size_t idx; unsigned int p2; /* Make sure this isn't called when a table already exists. */ _DIAGASSERT(htable == NULL); if (htable != NULL) { errno = EINVAL; return 0; } /* If nel is too small, make it min sized. */ if (nel < MIN_BUCKETS) nel = MIN_BUCKETS; /* If it's too large, cap it. */ if (nel > MAX_BUCKETS) nel = MAX_BUCKETS; /* If it's is not a power of two in size, round up. */ if ((nel & (nel - 1)) != 0) { for (p2 = 0; nel != 0; p2++) nel >>= 1; _DIAGASSERT(p2 <= MAX_BUCKETS_LG2); nel = 1 << p2; } /* Allocate the table. */ htablesize = nel; htable = calloc(htablesize, sizeof htable[0]); if (htable == NULL) { errno = ENOMEM; return 0; } /* Initialize it. */ for (idx = 0; idx < htablesize; idx++) SLIST_INIT(&htable[idx]); return 1; } void hdestroy(void) { struct internal_entry *ie; size_t idx; _DIAGASSERT(htable != NULL); if (htable == NULL) return; for (idx = 0; idx < htablesize; idx++) { while (!SLIST_EMPTY(&htable[idx])) { ie = SLIST_FIRST(&htable[idx]); SLIST_REMOVE_HEAD(&htable[idx], link); free(ie->ent.key); free(ie); } } free(htable); htable = NULL; } ENTRY * hsearch(ENTRY item, ACTION action) { struct internal_head *head; struct internal_entry *ie; uint32_t hashval; size_t len; _DIAGASSERT(htable != NULL); _DIAGASSERT(item.key != NULL); _DIAGASSERT(action == ENTER || action == FIND); len = strlen(item.key); hashval = __default_hash(item.key, len); head = &htable[hashval & (htablesize - 1)]; ie = SLIST_FIRST(head); while (ie != NULL) { if (strcmp(ie->ent.key, item.key) == 0) break; ie = SLIST_NEXT(ie, link); } if (ie != NULL) return &ie->ent; else if (action == FIND) return NULL; ie = malloc(sizeof *ie); if (ie == NULL) return NULL; ie->ent.key = item.key; ie->ent.data = item.data; SLIST_INSERT_HEAD(head, ie, link); return &ie->ent; }