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