NetBSD/usr.bin/locate/bigram/locate.bigram.c

151 lines
4.3 KiB
C

/* $NetBSD: locate.bigram.c,v 1.9 2000/05/06 10:26:45 mycroft Exp $ */
/*
* Copyright (c) 1989, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* James A. Woods.
*
* 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.
*/
#include <sys/cdefs.h>
#ifndef lint
__COPYRIGHT("@(#) Copyright (c) 1989, 1993\n\
The Regents of the University of California. All rights reserved.\n");
#endif /* not lint */
#ifndef lint
#if 0
static char sccsid[] = "@(#)locate.bigram.c 8.2 (Berkeley) 4/28/95";
#endif
__RCSID("$NetBSD: locate.bigram.c,v 1.9 2000/05/06 10:26:45 mycroft Exp $");
#endif /* not lint */
/*
* bigram < text > bigrams
*
* List bigrams for 'updatedb' script.
* Use 'code' to encode a file using this output.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/param.h> /* for MAXPATHLEN */
int main __P((int, char **));
static int compare_bigrams __P((const void *, const void *));
static void add_bigram __P((u_char, u_char));
static char buf1[MAXPATHLEN] = " ";
static char buf2[MAXPATHLEN];
struct bigram {
int count;
u_char b1, b2; /* needed for final sorting */
};
struct bigram bigrams[256 * 256];
static void
add_bigram(i1, i2)
u_char i1, i2;
{
if (i1 != '\n' && i2 != '\n')
bigrams[(i1<<8)+i2].count++;
}
static int
compare_bigrams(item1, item2)
const void *item1, *item2;
{
const struct bigram *it1=item1, *it2=item2;
if (it1->count != it2->count)
return it2->count - it1->count;
else if (it1->b1 != it2->b1)
return it2->b1 - it1->b1;
else
return it2->b2 - it2->b2;
}
int
main(argc, argv)
int argc;
char *argv[];
{
char *cp;
char *oldpath = buf1, *path = buf2;
struct bigram *bg;
int i;
/* initialize bigram array */
memset(bigrams, 0, sizeof(bigrams));
for(i=0; i < 65536; i++) {
bigrams[i].b1 = i / 256;
bigrams[i].b2 = i % 256;
}
while ( fgets ( path, sizeof(buf2), stdin ) != NULL ) {
/* skip longest common prefix */
for ( cp = path; *cp == *oldpath; cp++, oldpath++ )
if ( *oldpath == '\0' )
break;
/*
* output post-residue bigrams only
*/
for(; cp[0] != '\0' && cp[1] != '\0'; cp += 2)
add_bigram((u_char)cp[0], (u_char)cp[1]);
if (path == buf1) /* swap pointers */
path = buf2, oldpath = buf1;
else
path = buf1, oldpath = buf2;
}
/* sort the bigrams by how many times it appeared and their value */
heapsort((void *)bigrams, 256 * 256, sizeof(struct bigram),
compare_bigrams);
/* write 128 most frequent bigrams out */
bg = bigrams;
for (i = 0; i < 128 && bg->count > 0; i++, bg++) {
if (bg->b1 != '\0')
fputc(bg->b1, stdout);
if (bg->b2 != '\0')
fputc(bg->b2, stdout);
}
return (0);
}