/*
 * CDDL HEADER START
 *
 * The contents of this file are subject to the terms of the
 * Common Development and Distribution License, Version 1.0 only
 * (the "License").  You may not use this file except in compliance
 * with the License.
 *
 * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
 * or http://www.opensolaris.org/os/licensing.
 * See the License for the specific language governing permissions
 * and limitations under the License.
 *
 * When distributing Covered Code, include this CDDL HEADER in each
 * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
 * If applicable, add the following below this CDDL HEADER, with the
 * fields enclosed by brackets "[]" replaced with your own identifying
 * information: Portions Copyright [yyyy] [name of copyright owner]
 *
 * CDDL HEADER END
 */
/*
 * Copyright 2005 Sun Microsystems, Inc.  All rights reserved.
 * Use is subject to license terms.
 */

/*      Copyright (c) 1984, 1986, 1987, 1988, 1989 AT&T */
/*        All Rights Reserved   */

#include <stdlib.h>
#include "hash.h"

#define LOCHWIDTH 3
#define HICHWIDTH 3
#define CHARWIDTH (LOCHWIDTH+HICHWIDTH)
#define LOCHMASK ((1<<LOCHWIDTH)-1)

/*
 * if HASHWIDTH + CHARWIDTH < bitsizeof(long)
 * one could make LOCHWIDTH=6 and HICHWIDTH=0
 * and simplify accordingly; the hanky-panky
 * is to avoid overflow in long multiplication
 */
#define NC 30

static long hashsize = HASHSIZE;
static long pow2[NC*2];

static signed char hashtab[] = {
-1,     -1,     -1,     -1,     -1,     -1,     0,      31,     /*  &' */
-1,     -1,     -1,     -1,     68,     -1,     65,     -1,
2,      25,     20,     35,     54,     61,     40,     39,     /* 0-7 */
42,     33,     64,     67,     -1,     -1,     -1,     66,
-1,     60,     43,     30,     5,      16,     47,     18,     /* A-G */
41,     36,     51,     6,      13,     56,     55,     58,
49,     12,     59,     46,     21,     32,     63,     34,
57,     52,     3,      -1,     -1,     -1,     -1,     -1,
-1,     22,     29,     8,      7,      10,     1,      28,     /* a-g */
11,     62,     37,     48,     15,     50,     9,      4,
19,     38,     45,     24,     23,     26,     17,     44,
27,     14,     53,     -1,     -1,     -1,     -1,     -1
};


unsigned long
hash(char *s)
{
        int c;
        long *lp;
        unsigned long h = 0;
        for (lp = pow2; (c = *s++) != 0; ) {
                c = hashtab[c-' '];
                h += (c&LOCHMASK) * *lp++;
                h += (c>>LOCHWIDTH) * *lp++;
                h %= hashsize;
        }
        return (h);
}

void
hashinit(void)
{
#if ((1L << (HASHWIDTH+LOCHWIDTH) == 0) || (1L << (HASHWIDTH+HICHWIDTH) == 0))
        abort();        /* overflow is imminent */
#else
        int i;

        pow2[0] = 1L<<(HASHWIDTH-CHARWIDTH-2);
        for (i = 0; i < 2*NC-3; i += 2) {
                pow2[i+1] = (pow2[i]<<LOCHWIDTH) % hashsize;
                pow2[i+2] = (pow2[i+1]<<HICHWIDTH) % hashsize;
        }
#endif
}