cmd/spell/hashlook.c

/*
 * 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   */

#pragma ident   "%Z%%M% %I% %E% SMI"

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

unsigned *table;
int hindex[NI];

#define B (BYTE * sizeof (unsigned))
#define L (BYTE * sizeof (long)-1)
#define MASK (~((unsigned long)1L<<L))

#ifdef pdp11    /* sizeof (unsigned)==sizeof(long)/2 */
#define fetch(wp, bp)\
    (((((long)wp[0]<<B)|wp[1])<<(B-bp))|(wp[2]>>bp))
#else       /* sizeof (unsigned)==sizeof(long) */
#define fetch(wp, bp) ((wp[0] << (B - bp)) | (wp[1] >> bp))
#endif

int
hashlook(char *s)
{
    unsigned long h;
    unsigned long t;
    int bp;
    unsigned *wp;
    long sum;
    unsigned *tp;

    h = hash(s);
    t = h>>(HASHWIDTH-INDEXWIDTH);
    wp = &table[hindex[t]];
    tp = &table[hindex[t+1]];
    bp = B;
    sum = (long)t<<(HASHWIDTH-INDEXWIDTH);
    for (;;) {
        {
            /*
             * this block is equivalent to:
             * bp -= decode((fetch(wp, bp) >> 1) & MASK, &t);
             */
            long y;
            long v;

            /*
             * shift 32 on those machines leaves destination
             * unchanged
             */
            if (bp == 0)
                y = 0;
            else
                y = wp[0] << (B - bp);
            if (bp < 32)
                y |= (wp[1] >> bp);
            y = (y >> 1) & MASK;
            if (y < cs) {
                t = y >> (long) (L+1-w);
                bp -= w-1;
            } else {
                for (bp -= w, v = v0; y >= qcs;
                    y = (y << 1) & MASK, v += n)
                    bp -= 1;
                t = v + (y>> (long)(L-w));
            }
        }
        while (bp <= 0) {
            bp += B;
            wp++;
        }
        if (wp >= tp && (wp > tp||bp < B))
            return (0);
        sum += t;
        if (sum < h)
            continue;
        return (sum == h);
    }
}


int
prime(char *file)
{
    FILE *f;

#ifdef pdp11    /* because of insufficient address space for buffers */
    fd = dup(0);
    close(0);
    if (open(file, 0) != 0)
        return (0);
    f = stdin;
    if (rhuff(f) == 0 || read(fileno(f), (char *)hindex,
        NI * sizeof (*hindex)) != NI * sizeof (*hindex) ||
        (table = (unsigned *)malloc(hindex[NI-1] * sizeof (*table))) == 0 ||
        read(fileno(f), (char *)table, sizeof (*table) * hindex[NI-1]) !=
        hindex[NI-1] * sizeof (*table))
        return (0);
    close(0);
    if (dup(fd) != 0)
        return (0);
    close(fd);
#else
    if ((f = fopen(file, "r")) == NULL)
        return (0);
    if (rhuff(f) == 0 ||
        fread((char *)hindex, sizeof (*hindex),  NI, f) != NI ||
        (table = (unsigned *)malloc(hindex[NI-1] * sizeof (*table))) == 0 ||
        fread((char *)table, sizeof (*table), hindex[NI-1], f) !=
        hindex[NI-1])
        return (0);
    (void) fclose(f);
#endif
    hashinit();
    return (1);
}