[apple/libc.git] / db / hash / hash_func.c

/*
 * Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
 *
 * @APPLE_LICENSE_HEADER_START@
 * 
 * Copyright (c) 1999-2003 Apple Computer, Inc.  All Rights Reserved.
 * 
 * This file contains Original Code and/or Modifications of Original Code
 * as defined in and that are subject to the Apple Public Source License
 * Version 2.0 (the 'License'). You may not use this file except in
 * compliance with the License. Please obtain a copy of the License at
 * http://www.opensource.apple.com/apsl/ and read it before using this
 * file.
 * 
 * The Original Code and all software distributed under the License are
 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
 * Please see the License for the specific language governing rights and
 * limitations under the License.
 * 
 * @APPLE_LICENSE_HEADER_END@
 */
/*-
 * Copyright (c) 1990, 1993
 *	The Regents of the University of California.  All rights reserved.
 *
 * This code is derived from software contributed to Berkeley by
 * Margo Seltzer.
 *
 * 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 by the University of
 *	California, Berkeley and its contributors.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
 */

#if defined(LIBC_SCCS) && !defined(lint)
static char sccsid[] = "@(#)hash_func.c	8.2 (Berkeley) 2/21/94";
#endif /* LIBC_SCCS and not lint */
#include <sys/cdefs.h>

#include <sys/types.h>

#include <db.h>
#include "hash.h"
#include "page.h"
#include "extern.h"

static u_int32_t hash1(const void *, size_t) ;
static u_int32_t hash2(const void *, size_t) ;
static u_int32_t hash3(const void *, size_t) ;
static u_int32_t hash4(const void *, size_t);

/* Global default hash function */
u_int32_t (*__default_hash)(const void *, size_t) = hash4;

/*
 * HASH FUNCTIONS
 *
 * Assume that we've already split the bucket to which this key hashes,
 * calculate that bucket, and check that in fact we did already split it.
 *
 * This came from ejb's hsearch.
 */

#define PRIME1		37
#define PRIME2		1048583

static u_int32_t
hash1(keyarg, len)
	const void *keyarg;
	size_t len;
{
	const u_char *key;
	u_int32_t h;

	/* Convert string to integer */
	for (key = keyarg, h = 0; len--;)
		h = h * PRIME1 ^ (*key++ - ' ');
	h %= PRIME2;
	return (h);
}

/*
 * Phong's linear congruential hash
 */
#define dcharhash(h, c)	((h) = 0x63c63cd9*(h) + 0x9c39c33d + (c))

static u_int32_t
hash2(keyarg, len)
	const void *keyarg;
	size_t len;
{
	const u_char *e, *key;
	u_int32_t h;
	u_char c;

	key = keyarg;
	e = key + len;
	for (h = 0; key != e;) {
		c = *key++;
		if (!c && key > e)
			break;
		dcharhash(h, c);
	}
	return (h);
}

/*
 * This is INCREDIBLY ugly, but fast.  We break the string up into 8 byte
 * units.  On the first time through the loop we get the "leftover bytes"
 * (strlen % 8).  On every other iteration, we perform 8 HASHC's so we handle
 * all 8 bytes.  Essentially, this saves us 7 cmp & branch instructions.  If
 * this routine is heavily used enough, it's worth the ugly coding.
 *
 * OZ's original sdbm hash
 */
static u_int32_t
hash3(keyarg, len)
	const void *keyarg;
	size_t len;
{
	const u_char *key;
	size_t loop;
	u_int32_t h;

#define HASHC   h = *key++ + 65599 * h

	h = 0;
	key = keyarg;
	if (len > 0) {
		loop = (len + 8 - 1) >> 3;

		switch (len & (8 - 1)) {
		case 0:
			do {
				HASHC;
				/* FALLTHROUGH */
		case 7:
				HASHC;
				/* FALLTHROUGH */
		case 6:
				HASHC;
				/* FALLTHROUGH */
		case 5:
				HASHC;
				/* FALLTHROUGH */
		case 4:
				HASHC;
				/* FALLTHROUGH */
		case 3:
				HASHC;
				/* FALLTHROUGH */
		case 2:
				HASHC;
				/* FALLTHROUGH */
		case 1:
				HASHC;
			} while (--loop);
		}
	}
	return (h);
}

/* Hash function from Chris Torek. */
static u_int32_t
hash4(keyarg, len)
	const void *keyarg;
	size_t len;
{
	const u_char *key;
	size_t loop;
	u_int32_t h;

#define HASH4a   h = (h << 5) - h + *key++;
#define HASH4b   h = (h << 5) + h + *key++;
#define HASH4 HASH4b

	h = 0;
	key = keyarg;
	if (len > 0) {
		loop = (len + 8 - 1) >> 3;

		switch (len & (8 - 1)) {
		case 0:
			do {
				HASH4;
				/* FALLTHROUGH */
		case 7:
				HASH4;
				/* FALLTHROUGH */
		case 6:
				HASH4;
				/* FALLTHROUGH */
		case 5:
				HASH4;
				/* FALLTHROUGH */
		case 4:
				HASH4;
				/* FALLTHROUGH */
		case 3:
				HASH4;
				/* FALLTHROUGH */
		case 2:
				HASH4;
				/* FALLTHROUGH */
		case 1:
				HASH4;
			} while (--loop);
		}
	}
	return (h);
}
Commit	Line	Data
e9ce8d39	1	/*
9385eb3d	2	* Copyright (c) 2003 Apple Computer, Inc. All rights reserved.
e9ce8d39 A	3	*
	4	* @APPLE_LICENSE_HEADER_START@
	5	*
734aad71	6	* Copyright (c) 1999-2003 Apple Computer, Inc. All Rights Reserved.
e9ce8d39	7	*
734aad71 A	8	* This file contains Original Code and/or Modifications of Original Code
	9	* as defined in and that are subject to the Apple Public Source License
	10	* Version 2.0 (the 'License'). You may not use this file except in
	11	* compliance with the License. Please obtain a copy of the License at
	12	* http://www.opensource.apple.com/apsl/ and read it before using this
	13	* file.
	14	*
	15	* The Original Code and all software distributed under the License are
	16	* distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
e9ce8d39 A	17	* EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
e9ce8d39 A	18	* INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
734aad71 A	19	* FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
	20	* Please see the License for the specific language governing rights and
	21	* limitations under the License.
e9ce8d39 A	22	*
	23	* @APPLE_LICENSE_HEADER_END@
	24	*/
9385eb3d	25	/*-
e9ce8d39 A	26	* Copyright (c) 1990, 1993
	27	* The Regents of the University of California. All rights reserved.
	28	*
	29	* This code is derived from software contributed to Berkeley by
	30	* Margo Seltzer.
	31	*
	32	* Redistribution and use in source and binary forms, with or without
	33	* modification, are permitted provided that the following conditions
	34	* are met:
	35	* 1. Redistributions of source code must retain the above copyright
	36	* notice, this list of conditions and the following disclaimer.
	37	* 2. Redistributions in binary form must reproduce the above copyright
	38	* notice, this list of conditions and the following disclaimer in the
	39	* documentation and/or other materials provided with the distribution.
	40	* 3. All advertising materials mentioning features or use of this software
	41	* must display the following acknowledgement:
	42	* This product includes software developed by the University of
	43	* California, Berkeley and its contributors.
	44	* 4. Neither the name of the University nor the names of its contributors
	45	* may be used to endorse or promote products derived from this software
	46	* without specific prior written permission.
	47	*
	48	* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
	49	* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
	50	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
	51	* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
	52	* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
	53	* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
	54	* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
	55	* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
	56	* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
	57	* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
	58	* SUCH DAMAGE.
	59	*/
	60
9385eb3d A	61	#if defined(LIBC_SCCS) && !defined(lint)
	62	static char sccsid[] = "@(#)hash_func.c 8.2 (Berkeley) 2/21/94";
	63	#endif /* LIBC_SCCS and not lint */
	64	#include <sys/cdefs.h>
e9ce8d39 A	65
	66	#include <sys/types.h>
	67
	68	#include <db.h>
	69	#include "hash.h"
	70	#include "page.h"
	71	#include "extern.h"
	72
9385eb3d A	73	static u_int32_t hash1(const void *, size_t) ;
	74	static u_int32_t hash2(const void *, size_t) ;
	75	static u_int32_t hash3(const void *, size_t) ;
	76	static u_int32_t hash4(const void *, size_t);
e9ce8d39 A	77
e9ce8d39 A	78	/* Global default hash function */
9385eb3d	79	u_int32_t (__default_hash)(const void , size_t) = hash4;
e9ce8d39 A	80
	81	/*
	82	* HASH FUNCTIONS
	83	*
	84	* Assume that we've already split the bucket to which this key hashes,
	85	* calculate that bucket, and check that in fact we did already split it.
	86	*
	87	* This came from ejb's hsearch.
	88	*/
	89
	90	#define PRIME1 37
	91	#define PRIME2 1048583
	92
	93	static u_int32_t
	94	hash1(keyarg, len)
	95	const void *keyarg;
9385eb3d	96	size_t len;
e9ce8d39	97	{
9385eb3d A	98	const u_char *key;
9385eb3d A	99	u_int32_t h;
e9ce8d39 A	100
	101	/* Convert string to integer */
	102	for (key = keyarg, h = 0; len--;)
	103	h = h * PRIME1 ^ (*key++ - ' ');
	104	h %= PRIME2;
	105	return (h);
	106	}
	107
	108	/*
	109	* Phong's linear congruential hash
	110	*/
	111	#define dcharhash(h, c) ((h) = 0x63c63cd9*(h) + 0x9c39c33d + (c))
	112
	113	static u_int32_t
	114	hash2(keyarg, len)
	115	const void *keyarg;
	116	size_t len;
	117	{
9385eb3d A	118	const u_char e, key;
	119	u_int32_t h;
	120	u_char c;
e9ce8d39 A	121
	122	key = keyarg;
	123	e = key + len;
	124	for (h = 0; key != e;) {
	125	c = *key++;
	126	if (!c && key > e)
	127	break;
	128	dcharhash(h, c);
	129	}
	130	return (h);
	131	}
	132
	133	/*
	134	* This is INCREDIBLY ugly, but fast. We break the string up into 8 byte
	135	* units. On the first time through the loop we get the "leftover bytes"
	136	* (strlen % 8). On every other iteration, we perform 8 HASHC's so we handle
	137	* all 8 bytes. Essentially, this saves us 7 cmp & branch instructions. If
	138	* this routine is heavily used enough, it's worth the ugly coding.
	139	*
	140	* OZ's original sdbm hash
	141	*/
	142	static u_int32_t
	143	hash3(keyarg, len)
	144	const void *keyarg;
9385eb3d	145	size_t len;
e9ce8d39	146	{
9385eb3d A	147	const u_char *key;
	148	size_t loop;
	149	u_int32_t h;
e9ce8d39 A	150
	151	#define HASHC h = key++ + 65599 h
	152
	153	h = 0;
	154	key = keyarg;
	155	if (len > 0) {
	156	loop = (len + 8 - 1) >> 3;
	157
	158	switch (len & (8 - 1)) {
	159	case 0:
	160	do {
	161	HASHC;
	162	/* FALLTHROUGH */
	163	case 7:
	164	HASHC;
	165	/* FALLTHROUGH */
	166	case 6:
	167	HASHC;
	168	/* FALLTHROUGH */
	169	case 5:
	170	HASHC;
	171	/* FALLTHROUGH */
	172	case 4:
	173	HASHC;
	174	/* FALLTHROUGH */
	175	case 3:
	176	HASHC;
	177	/* FALLTHROUGH */
	178	case 2:
	179	HASHC;
	180	/* FALLTHROUGH */
	181	case 1:
	182	HASHC;
	183	} while (--loop);
	184	}
	185	}
	186	return (h);
	187	}
	188
	189	/* Hash function from Chris Torek. */
	190	static u_int32_t
	191	hash4(keyarg, len)
	192	const void *keyarg;
9385eb3d	193	size_t len;
e9ce8d39	194	{
9385eb3d A	195	const u_char *key;
	196	size_t loop;
	197	u_int32_t h;
e9ce8d39 A	198
	199	#define HASH4a h = (h << 5) - h + *key++;
	200	#define HASH4b h = (h << 5) + h + *key++;
	201	#define HASH4 HASH4b
	202
	203	h = 0;
	204	key = keyarg;
	205	if (len > 0) {
	206	loop = (len + 8 - 1) >> 3;
	207
	208	switch (len & (8 - 1)) {
	209	case 0:
	210	do {
	211	HASH4;
	212	/* FALLTHROUGH */
	213	case 7:
	214	HASH4;
	215	/* FALLTHROUGH */
	216	case 6:
	217	HASH4;
	218	/* FALLTHROUGH */
	219	case 5:
	220	HASH4;
	221	/* FALLTHROUGH */
	222	case 4:
	223	HASH4;
	224	/* FALLTHROUGH */
	225	case 3:
	226	HASH4;
	227	/* FALLTHROUGH */
	228	case 2:
	229	HASH4;
	230	/* FALLTHROUGH */
	231	case 1:
	232	HASH4;
	233	} while (--loop);
	234	}
	235	}
	236	return (h);
	237	}