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/*
* Copyright (c) 2000 Silicon Graphics, Inc. All Rights Reserved.
*
* This program is free software; you can redistribute it and/or modify it
* under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* This program is distributed in the hope that it would be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
*
* Further, this software is distributed without any warranty that it is
* free of the rightful claim of any third person regarding infringement
* or the like. Any license provided herein, whether implied or
* otherwise, applies only to this software file. Patent licenses, if
* any, provided herein do not apply to combinations of this program with
* other software, or any other product whatsoever.
*
* You should have received a copy of the GNU General Public License along
* with this program; if not, write the Free Software Foundation, Inc., 59
* Temple Place - Suite 330, Boston MA 02111-1307, USA.
*
* Contact information: Silicon Graphics, Inc., 1600 Amphitheatre Pkwy,
* Mountain View, CA 94043, or:
*
* http://www.sgi.com
*
* For further information regarding this notice, see:
*
* http://oss.sgi.com/projects/GenInfo/NoticeExplan/
*/
#include <string.h>
#include "pattern.h"
/*
* The routines in this module are used to fill/check a data buffer
* with/against a known pattern.
*/
int
pattern_check(buf, buflen, pat, patlen, patshift)
char *buf;
int buflen;
char *pat;
int patlen;
int patshift;
{
int nb, ncmp, nleft;
char *cp;
if (patlen)
patshift = patshift % patlen;
cp = buf;
nleft = buflen;
/*
* The following 2 blocks of code are to compare the first patlen
* bytes of buf. We need 2 checks if patshift is > 0 since we
* must check the last (patlen - patshift) bytes, and then the
* first (patshift) bytes.
*/
nb = patlen - patshift;
if (nleft < nb) {
return (memcmp(cp, pat + patshift, nleft) ? -1 : 0);
} else {
if (memcmp(cp, pat + patshift, nb))
return -1;
nleft -= nb;
cp += nb;
}
if (patshift > 0) {
nb = patshift;
if (nleft < nb) {
return (memcmp(cp, pat, nleft) ? -1 : 0);
} else {
if (memcmp(cp, pat, nb))
return -1;
nleft -= nb;
cp += nb;
}
}
/*
* Now, verify the rest of the buffer using the algorithm described
* in the function header.
*/
ncmp = cp - buf;
while (ncmp < buflen) {
nb = (ncmp < nleft) ? ncmp : nleft;
if (memcmp(buf, cp, nb))
return -1;
cp += nb;
ncmp += nb;
nleft -= nb;
}
return 0;
}
int
pattern_fill(buf, buflen, pat, patlen, patshift)
char *buf;
int buflen;
char *pat;
int patlen;
int patshift;
{
int trans, ncopied, nleft;
char *cp;
if (patlen)
patshift = patshift % patlen;
cp = buf;
nleft = buflen;
/*
* The following 2 blocks of code are to fill the first patlen
* bytes of buf. We need 2 sections if patshift is > 0 since we
* must first copy the last (patlen - patshift) bytes into buf[0]...,
* and then the first (patshift) bytes of pattern following them.
*/
trans = patlen - patshift;
if (nleft < trans) {
memcpy(cp, pat + patshift, nleft);
return 0;
} else {
memcpy(cp, pat + patshift, trans);
nleft -= trans;
cp += trans;
}
if (patshift > 0) {
trans = patshift;
if (nleft < trans) {
memcpy(cp, pat, nleft);
return 0;
} else {
memcpy(cp, pat, trans);
nleft -= trans;
cp += trans;
}
}
/*
* Now, fill the rest of the buffer using the algorithm described
* in the function header comment.
*/
ncopied = cp - buf;
while (ncopied < buflen) {
trans = (ncopied < nleft) ? ncopied : nleft;
memcpy(cp, buf, trans);
cp += trans;
ncopied += trans;
nleft -= trans;
}
return(0);
}

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