1/*
2 * CDDL HEADER START
3 *
4 * The contents of this file are subject to the terms of the
5 * Common Development and Distribution License, Version 1.0 only
6 * (the "License").  You may not use this file except in compliance
7 * with the License.
8 *
9 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
10 * or http://www.opensolaris.org/os/licensing.
11 * See the License for the specific language governing permissions
12 * and limitations under the License.
13 *
14 * When distributing Covered Code, include this CDDL HEADER in each
15 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
16 * If applicable, add the following below this CDDL HEADER, with the
17 * fields enclosed by brackets "[]" replaced with your own identifying
18 * information: Portions Copyright [yyyy] [name of copyright owner]
19 *
20 * CDDL HEADER END
21 */
22/*
23 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
24 * Use is subject to license terms.
25 */
26
27/*	Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T	*/
28/*	  All Rights Reserved  	*/
29
30#pragma ident	"%Z%%M%	%I%	%E% SMI"
31
32
33#include <stdlib.h>
34#include "hash.h"
35
36#define	LOCHWIDTH 3
37#define	HICHWIDTH 3
38#define	CHARWIDTH (LOCHWIDTH+HICHWIDTH)
39#define	LOCHMASK ((1<<LOCHWIDTH)-1)
40
41/*
42 * if HASHWIDTH + CHARWIDTH < bitsizeof(long)
43 * one could make LOCHWIDTH=6 and HICHWIDTH=0
44 * and simplify accordingly; the hanky-panky
45 * is to avoid overflow in long multiplication
46 */
47#define	NC 30
48
49static long hashsize = HASHSIZE;
50static long pow2[NC*2];
51
52static signed char hashtab[] = {
53-1,	-1,	-1,	-1,	-1,	-1,	0,	31,	/*  &' */
54-1,	-1,	-1,	-1,	68,	-1,	65,	-1,
552,	25,	20,	35,	54,	61,	40,	39,	/* 0-7 */
5642,	33,	64,	67,	-1,	-1,	-1,	66,
57-1,	60,	43,	30,	5,	16,	47,	18,	/* A-G */
5841,	36,	51,	6,	13,	56,	55,	58,
5949,	12,	59,	46,	21,	32,	63,	34,
6057,	52,	3,	-1,	-1,	-1,	-1,	-1,
61-1,	22,	29,	8,	7,	10,	1,	28,	/* a-g */
6211,	62,	37,	48,	15,	50,	9,	4,
6319,	38,	45,	24,	23,	26,	17,	44,
6427,	14,	53,	-1,	-1,	-1,	-1,	-1
65};
66
67
68unsigned long
69hash(char *s)
70{
71	int c;
72	long *lp;
73	unsigned long h = 0;
74	for (lp = pow2; (c = *s++) != 0; ) {
75		c = hashtab[c-' '];
76		h += (c&LOCHMASK) * *lp++;
77		h += (c>>LOCHWIDTH) * *lp++;
78		h %= hashsize;
79	}
80	return (h);
81}
82
83void
84hashinit(void)
85{
86#if ((1L << (HASHWIDTH+LOCHWIDTH) == 0) || (1L << (HASHWIDTH+HICHWIDTH) == 0))
87	abort();	/* overflow is imminent */
88#else
89	int i;
90
91	pow2[0] = 1L<<(HASHWIDTH-CHARWIDTH-2);
92	for (i = 0; i < 2*NC-3; i += 2) {
93		pow2[i+1] = (pow2[i]<<LOCHWIDTH) % hashsize;
94		pow2[i+2] = (pow2[i+1]<<HICHWIDTH) % hashsize;
95	}
96#endif
97}
98