240 lines
6.2 KiB
C
240 lines
6.2 KiB
C
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/* $NetBSD: bm.c,v 1.11 2003/08/07 16:43:47 agc Exp $ */
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/*-
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* Copyright (c) 1994
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Andrew Hume of AT&T Bell Laboratories.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)bm.c 8.7 (Berkeley) 6/21/94";
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#else
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__RCSID("$NetBSD: bm.c,v 1.11 2003/08/07 16:43:47 agc Exp $");
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#endif
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#endif /* LIBC_SCCS && not lint */
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#include "namespace.h"
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#include <sys/types.h>
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#include <assert.h>
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#include <bm.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <string.h>
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#ifdef __weak_alias
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__weak_alias(bm_comp,_bm_comp)
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__weak_alias(bm_exec,_bm_exec)
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__weak_alias(bm_free,_bm_free)
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#endif
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/*
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* XXX
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* The default frequency table starts at 99 and counts down. The default
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* table should probably be oriented toward text, and will necessarily be
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* locale specific. This one is for English. It was derived from the
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* OSF/1 and 4.4BSD formatted and unformatted manual pages, and about 100Mb
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* of email and random text. Change it if you can find something better.
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*/
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static u_char const freq_def[256] = {
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 77, 90, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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99, 28, 42, 27, 16, 14, 20, 51,
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66, 65, 59, 24, 75, 76, 84, 56,
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72, 74, 64, 55, 54, 47, 41, 37,
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44, 61, 70, 43, 23, 53, 49, 22,
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33, 58, 40, 46, 45, 57, 60, 26,
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30, 63, 21, 12, 32, 50, 38, 39,
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34, 11, 48, 67, 62, 35, 15, 29,
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71, 18, 9, 17, 25, 13, 10, 52,
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36, 95, 78, 86, 87, 98, 82, 80,
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88, 94, 19, 68, 89, 83, 93, 96,
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81, 7, 91, 92, 97, 85, 69, 73,
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31, 79, 8, 5, 4, 6, 3, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0,
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};
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bm_pat *
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bm_comp(pb, len, freq)
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u_char const *pb;
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size_t len;
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u_char const *freq;
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{
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u_char const *pe, *p;
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size_t *d, r;
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int j;
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int sv_errno;
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bm_pat *pat;
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_DIAGASSERT(pb != NULL);
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/* freq may be NULL */
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if (len == 0) {
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errno = EINVAL;
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return (NULL);
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}
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if ((pat = malloc(sizeof(*pat))) == NULL)
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return (NULL);
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pat->pat = NULL;
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pat->delta = NULL;
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pat->patlen = len; /* copy pattern */
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if ((pat->pat = malloc(pat->patlen)) == NULL)
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goto mem;
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memcpy(pat->pat, pb, pat->patlen);
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/* get skip delta */
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if ((pat->delta = malloc(256 * sizeof(*d))) == NULL)
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goto mem;
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for (j = 0, d = pat->delta; j < 256; j++)
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d[j] = pat->patlen;
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for (pe = pb + pat->patlen - 1; pb <= pe; pb++)
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d[*pb] = pe - pb;
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if (freq == NULL) /* default freq table */
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freq = freq_def;
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r = 0; /* get guard */
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for (pb = pat->pat, pe = pb + pat->patlen - 1; pb < pe; pb++)
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if (freq[*pb] < freq[pat->pat[r]])
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r = pb - pat->pat;
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pat->rarec = pat->pat[r];
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pat->rareoff = r - (pat->patlen - 1);
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/* get md2 shift */
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for (pe = pat->pat + pat->patlen - 1, p = pe - 1; p >= pat->pat; p--)
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if (*p == *pe)
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break;
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/* *p is first leftward reoccurrence of *pe */
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pat->md2 = pe - p;
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return (pat);
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mem: sv_errno = errno;
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bm_free(pat);
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errno = sv_errno;
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return (NULL);
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}
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void
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bm_free(pat)
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bm_pat *pat;
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{
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_DIAGASSERT(pat != NULL);
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if (pat->pat != NULL)
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free(pat->pat);
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if (pat->delta != NULL)
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free(pat->delta);
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free(pat);
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}
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u_char *
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bm_exec(pat, base, n)
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bm_pat *pat;
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u_char *base;
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size_t n;
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{
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u_char *e, *ep, *p, *q, *s;
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size_t *d0, k, md2, n1, ro;
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int rc;
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_DIAGASSERT(pat != NULL);
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_DIAGASSERT(base != NULL);
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if (n == 0)
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return (NULL);
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d0 = pat->delta;
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n1 = pat->patlen - 1;
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md2 = pat->md2;
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ro = pat->rareoff;
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rc = pat->rarec;
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ep = pat->pat + pat->patlen - 1;
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s = base + (pat->patlen - 1);
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/* fast loop up to n - 3 * patlen */
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e = base + n - 3 * pat->patlen;
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while (s < e) {
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k = d0[*s]; /* ufast skip loop */
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while (k) {
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k = d0[*(s += k)];
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k = d0[*(s += k)];
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}
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if (s >= e)
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break;
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if (s[ro] != rc) /* guard test */
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goto mismatch1;
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/* fwd match */
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for (p = pat->pat, q = s - n1; p < ep;)
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if (*q++ != *p++)
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goto mismatch1;
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return (s - n1);
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mismatch1: s += md2; /* md2 shift */
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}
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/* slow loop up to end */
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e = base + n;
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while (s < e) {
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s += d0[*s]; /* step */
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if (s >= e)
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break;
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if (s[ro] != rc) /* guard test */
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goto mismatch2;
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/* fwd match */
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for (p = pat->pat, q = s - n1; p <= ep;)
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if (*q++ != *p++)
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goto mismatch2;
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return (s - n1);
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mismatch2: s += md2; /* md2 shift */
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}
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return (NULL);
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}
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