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add Boyer-Moore string search routines, from Bostic. man page

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needs to be fixed for mandoc, and RCSID's need to be added.
This commit is contained in:
cgd 1994-06-22 00:15:22 +00:00
parent 2d77dbfd70
commit 7f79e48c1a
3 changed files with 339 additions and 6 deletions
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13
lib/libc/string/Makefile.inc
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@ -1,10 +1,10 @@
# from: @(#)Makefile.inc 5.6 (Berkeley) 3/5/91
# $Id: Makefile.inc,v 1.26 1994/02/25 07:42:01 phil Exp $
# $Id: Makefile.inc,v 1.27 1994/06/22 00:15:22 cgd Exp $
# string sources
.PATH: ${.CURDIR}/arch/${MACHINE_ARCH}/string ${.CURDIR}/string
SRCS+= memccpy.c strcasecmp.c strcoll.c strdup.c strerror.c \
SRCS+= bm.c memccpy.c strcasecmp.c strcoll.c strdup.c strerror.c \
strftime.c strmode.c strtok.c strxfrm.c
.if (${MACHINE_ARCH} == "m68k")
@ -120,12 +120,13 @@ strrchr.so: rindex.c
-o ${.TARGET}
.endif
MAN3+= bcmp.0 bcopy.0 bstring.0 bzero.0 ffs.0 index.0 memccpy.0 memchr.0 \
MAN3+= bm.0 bcmp.0 bcopy.0 bstring.0 bzero.0 ffs.0 index.0 memccpy.0 memchr.0 \
memcmp.0 memcpy.0 memmove.0 memset.0 rindex.0 strcasecmp.0 strcat.0 \
strchr.0 strcmp.0 strcoll.0 strcpy.0 strcspn.0 strerror.0 strftime.0 string.0 \
strlen.0 strmode.0 strdup.0 strpbrk.0 strrchr.0 strsep.0 strspn.0 \
strstr.0 strtok.0 strxfrm.0 swab.0
strchr.0 strcmp.0 strcoll.0 strcpy.0 strcspn.0 strerror.0 strftime.0 \
string.0 strlen.0 strmode.0 strdup.0 strpbrk.0 strrchr.0 strsep.0 \
strspn.0 strstr.0 strtok.0 strxfrm.0 swab.0
MLINKS+=bm.3 bm_comp.3 bm.3 bm_exec.3 bm.3 bm_free.3
MLINKS+=strcasecmp.3 strncasecmp.3
MLINKS+=strcat.3 strncat.3
MLINKS+=strcmp.3 strncmp.3

113
lib/libc/string/bm.3 Normal file
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@ -0,0 +1,113 @@
.\" Copyright (c) 1994
.\" The Regents of the University of California. All rights reserved.
.\"
.\" This code is derived from software contributed to Berkeley by
.\" Andrew Hume of AT&T Bell Laboratories.
.\"
.\" 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. All advertising materials mentioning features or use of this software
.\" must display the following acknowledgement:
.\" This product includes software developed by the University of
.\" California, Berkeley and its contributors.
.\" 4. 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.
.\"
.\" @(#)bm.3 8.4 (Berkeley) 6/21/94
.\"
.TH BM 3
.SH NAME
bm_comp, bm_exec, bm_free \- Boyer-Moore string search
.SH SYNOPSIS
.ft B
#include <sys/types.h>
.br
#include <bm.h>
.sp
bm_pat *
.br
bm_comp(u_char *pattern, size_t patlen, u_char freq[256]);
.sp
u_char *
.br
bm_exec(bm_pat *pdesc, u_char *text, size_t len);
.sp
void
.br
bm_free(bm_pat *pdesc);
.SH DESCRIPTION
These routines implement an efficient mechanism to find an
occurrence of a byte string within another byte string.
.PP
.I Bm_comp
evaluates the
.I patlen
bytes starting at
.IR pattern ,
and returns a pointer to a structure describing them.
The bytes referenced by
.I pattern
may be of any value.
.PP
The search takes advantage of the frequency distribution of the
bytes in the text to be searched.
If specified,
.I freq
should be an array of 256 values,
with higher values indicating that the corresponding character occurs
more frequently.
(A less than optimal frequency distribution can only result in less
than optimal performance, not incorrect results.)
If
.I freq
is NULL,
a system default table is used.
.PP
.I Bm_exec
returns a pointer to the leftmost occurrence of the string given to
.I bm_comp
within
.IR text ,
or NULL if none occurs.
The number of bytes in
.I text
must be specified by
.IR len .
.PP
Space allocated for the returned description is discarded
by calling
.I bm_free
with the returned description as an argument.
.PP
The asymptotic speed of
.I bm_exec
is
.RI O( len / patlen ).
.PP
.SH "SEE ALSO"
.IR regexp (3),
.IR strstr (3)
.sp
.IR "Fast String Searching" ,
Hume and Sunday,
Software Practice and Experience,
Vol. 21, 11 (November 1991) pp. 1221-48.

219
lib/libc/string/bm.c Normal file
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@ -0,0 +1,219 @@
/*-
* Copyright (c) 1994
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Andrew Hume of AT&T Bell Laboratories.
*
* 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. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. 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.
*/
#ifndef lint
static char sccsid[] = "@(#)bm.c 8.7 (Berkeley) 6/21/94";
#endif /* not lint */
#include <sys/types.h>
#include <bm.h>
#include <errno.h>
#include <stdlib.h>
#include <string.h>
/*
* XXX
* The default frequency table starts at 99 and counts down. The default
* table should probably be oriented toward text, and will necessarily be
* locale specific. This one is for English. It was derived from the
* OSF/1 and 4.4BSD formatted and unformatted manual pages, and about 100Mb
* of email and random text. Change it if you can find something better.
*/
static u_char const freq_def[256] = {
0, 0, 0, 0, 0, 0, 0, 0,
0, 77, 90, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
99, 28, 42, 27, 16, 14, 20, 51,
66, 65, 59, 24, 75, 76, 84, 56,
72, 74, 64, 55, 54, 47, 41, 37,
44, 61, 70, 43, 23, 53, 49, 22,
33, 58, 40, 46, 45, 57, 60, 26,
30, 63, 21, 12, 32, 50, 38, 39,
34, 11, 48, 67, 62, 35, 15, 29,
71, 18, 9, 17, 25, 13, 10, 52,
36, 95, 78, 86, 87, 98, 82, 80,
88, 94, 19, 68, 89, 83, 93, 96,
81, 7, 91, 92, 97, 85, 69, 73,
31, 79, 8, 5, 4, 6, 3, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
0, 0, 0, 0, 0, 0, 0, 0,
};
bm_pat *
bm_comp(pb, len, freq)
u_char const *pb;
size_t len;
u_char const *freq;
{
register u_char const *pe, *p;
register size_t *d, r;
register int j;
int sv_errno;
bm_pat *pat;
if (len == 0) {
errno = EINVAL;
return (NULL);
}
if ((pat = malloc(sizeof(*pat))) == NULL)
return (NULL);
pat->pat = NULL;
pat->delta = NULL;
pat->patlen = len; /* copy pattern */
if ((pat->pat = malloc(pat->patlen)) == NULL)
goto mem;
memcpy(pat->pat, pb, pat->patlen);
/* get skip delta */
if ((pat->delta = malloc(256 * sizeof(*d))) == NULL)
goto mem;
for (j = 0, d = pat->delta; j < 256; j++)
d[j] = pat->patlen;
for (pe = pb + pat->patlen - 1; pb <= pe; pb++)
d[*pb] = pe - pb;
if (freq == NULL) /* default freq table */
freq = freq_def;
r = 0; /* get guard */
for (pb = pat->pat, pe = pb + pat->patlen - 1; pb < pe; pb++)
if (freq[*pb] < freq[pat->pat[r]])
r = pb - pat->pat;
pat->rarec = pat->pat[r];
pat->rareoff = r - (pat->patlen - 1);
/* get md2 shift */
for (pe = pat->pat + pat->patlen - 1, p = pe - 1; p >= pat->pat; p--)
if (*p == *pe)
break;
/* *p is first leftward reoccurrence of *pe */
pat->md2 = pe - p;
return (pat);
mem: sv_errno = errno;
bm_free(pat);
errno = sv_errno;
return (NULL);
}
void
bm_free(pat)
bm_pat *pat;
{
if (pat->pat != NULL)
free(pat->pat);
if (pat->delta != NULL)
free(pat->delta);
free(pat);
}
u_char *
bm_exec(pat, base, n)
bm_pat *pat;
u_char *base;
size_t n;
{
register u_char *e, *ep, *p, *q, *s;
register size_t *d0, k, md2, n1, ro;
register int rc;
if (n == 0)
return (NULL);
d0 = pat->delta;
n1 = pat->patlen - 1;
md2 = pat->md2;
ro = pat->rareoff;
rc = pat->rarec;
ep = pat->pat + pat->patlen - 1;
s = base + (pat->patlen - 1);
/* fast loop up to n - 3 * patlen */
e = base + n - 3 * pat->patlen;
while (s < e) {
k = d0[*s]; /* ufast skip loop */
while (k) {
k = d0[*(s += k)];
k = d0[*(s += k)];
}
if (s >= e)
break;
if (s[ro] != rc) /* guard test */
goto mismatch1;
/* fwd match */
for (p = pat->pat, q = s - n1; p < ep;)
if (*q++ != *p++)
goto mismatch1;
return (s - n1);
mismatch1: s += md2; /* md2 shift */
}
/* slow loop up to end */
e = base + n;
while (s < e) {
s += d0[*s]; /* step */
if (s >= e)
break;
if (s[ro] != rc) /* guard test */
goto mismatch2;
/* fwd match */
for (p = pat->pat, q = s - n1; p < ep;)
if (*q++ != *p++)
goto mismatch2;
return (s - n1);
mismatch2: s += md2; /* md2 shift */
}
return (NULL);
}