minix/lib/libc/db/hash/hash_func.c
Ben Gras 2fe8fb192f Full switch to clang/ELF. Drop ack. Simplify.
There is important information about booting non-ack images in
docs/UPDATING. ack/aout-format images can't be built any more, and
booting clang/ELF-format ones is a little different. Updating to the
new boot monitor is recommended.

Changes in this commit:

	. drop boot monitor -> allowing dropping ack support
	. facility to copy ELF boot files to /boot so that old boot monitor
	  can still boot fairly easily, see UPDATING
	. no more ack-format libraries -> single-case libraries
	. some cleanup of OBJECT_FMT, COMPILER_TYPE, etc cases
	. drop several ack toolchain commands, but not all support
	  commands (e.g. aal is gone but acksize is not yet).
	. a few libc files moved to netbsd libc dir
	. new /bin/date as minix date used code in libc/
	. test compile fix
	. harmonize includes
	. /usr/lib is no longer special: without ack, /usr/lib plays no
	  kind of special bootstrapping role any more and bootstrapping
	  is done exclusively through packages, so releases depend even
	  less on the state of the machine making them now.
	. rename nbsd_lib* to lib*
	. reduce mtree
2012-02-14 14:52:02 +01:00

208 lines
4.9 KiB
C

/* $NetBSD: hash_func.c,v 1.13 2008/09/10 17:52:35 joerg Exp $ */
/*-
* 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. 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 HAVE_NBTOOL_CONFIG_H
#include "nbtool_config.h"
#endif
#include <sys/cdefs.h>
__RCSID("$NetBSD: hash_func.c,v 1.13 2008/09/10 17:52:35 joerg Exp $");
#include <sys/types.h>
#include <db.h>
#include "hash.h"
#include "page.h"
#include "extern.h"
#if 0
static uint32_t hash1(const void *, size_t) __attribute__((__unused__));
static uint32_t hash2(const void *, size_t) __attribute__((__unused__));
static uint32_t hash3(const void *, size_t) __attribute__((__unused__));
#endif
static uint32_t hash4(const void *, size_t) __attribute__((__unused__));
/* Global default hash function */
uint32_t (*__default_hash)(const void *, size_t) = hash4;
#if 0
/*
* 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 uint32_t
hash1(const void *keyarg, size_t len)
{
const uint8_t *key;
uint32_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 uint32_t
hash2(const void *keyarg, size_t len)
{
const uint8_t *e, *key;
uint32_t h;
uint8_t 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 uint32_t
hash3(const void *keyarg, size_t len)
{
const uint8_t *key;
size_t loop;
uint32_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);
}
#endif
/* Hash function from Chris Torek. */
static uint32_t
hash4(const void *keyarg, size_t len)
{
const uint8_t *key;
size_t loop;
uint32_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);
}