Import games/caesar and games/rot13
Change-Id: Ib6b074c6c525ee817b9182b17a06ae18851f5afe
This commit is contained in:
Jacob Adams
218
games/caesar/caesar.c
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218
games/caesar/caesar.c
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/* $NetBSD: caesar.c,v 1.22 2008/07/20 01:03:21 lukem 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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* Rick Adams.
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*
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* Authors:
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* Stan King, John Eldridge, based on algorithm suggested by
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* Bob Morris
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* 29-Sep-82
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* Roland Illig, 2005
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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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#ifndef lint
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__COPYRIGHT("@(#) Copyright (c) 1989, 1993\
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The Regents of the University of California. All rights reserved.");
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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[] = "@(#)caesar.c 8.1 (Berkeley) 5/31/93";
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#else
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__RCSID("$NetBSD: caesar.c,v 1.22 2008/07/20 01:03:21 lukem Exp $");
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#endif
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#endif /* not lint */
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#include <err.h>
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#include <errno.h>
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#include <limits.h>
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#include <math.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdlib.h>
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#define NCHARS (1 << CHAR_BIT)
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#define LETTERS (26)
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/*
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* letter frequencies (taken from some unix(tm) documentation)
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* (unix is a trademark of Bell Laboratories)
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*/
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static const unsigned char upper[LETTERS] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
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static const unsigned char lower[LETTERS] = "abcdefghijklmnopqrstuvwxyz";
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static double stdf[LETTERS] = {
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7.97, 1.35, 3.61, 4.78, 12.37, 2.01, 1.46, 4.49, 6.39, 0.04,
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0.42, 3.81, 2.69, 5.92, 6.96, 2.91, 0.08, 6.63, 8.77, 9.68,
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2.62, 0.81, 1.88, 0.23, 2.07, 0.06
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};
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static unsigned char rottbl[NCHARS];
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static void
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init_rottbl(int rot)
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{
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size_t i;
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rot %= LETTERS; /* prevent integer overflow */
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for (i = 0; i < NCHARS; i++)
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rottbl[i] = (unsigned char)i;
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for (i = 0; i < LETTERS; i++)
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rottbl[upper[i]] = upper[(i + rot) % LETTERS];
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for (i = 0; i < LETTERS; i++)
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rottbl[lower[i]] = lower[(i + rot) % LETTERS];
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}
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static void
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print_file(void)
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{
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int ch;
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while ((ch = getchar()) != EOF) {
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if (putchar(rottbl[ch]) == EOF) {
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err(EXIT_FAILURE, "<stdout>");
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/* NOTREACHED */
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}
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}
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}
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static void
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print_array(const unsigned char *a, size_t len)
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{
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size_t i;
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for (i = 0; i < len; i++) {
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if (putchar(rottbl[a[i]]) == EOF) {
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err(EXIT_FAILURE, "<stdout>");
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/* NOTREACHED */
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}
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}
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}
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static int
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get_rotation(const char *arg)
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{
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long rot;
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char *endp;
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errno = 0;
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rot = strtol(arg, &endp, 10);
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if (errno == 0 && (arg[0] == '\0' || *endp != '\0'))
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errno = EINVAL;
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if (errno == 0 && (rot < 0 || rot > INT_MAX))
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errno = ERANGE;
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if (errno)
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err(EXIT_FAILURE, "Bad rotation value `%s'", arg);
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return (int)rot;
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}
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static void
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guess_and_rotate(void)
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{
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unsigned char inbuf[2048];
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unsigned int obs[NCHARS];
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size_t i, nread;
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double dot, winnerdot;
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int try, winner;
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int ch;
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/* adjust frequency table to weight low probs REAL low */
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for (i = 0; i < LETTERS; i++)
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stdf[i] = log(stdf[i]) + log(LETTERS / 100.0);
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/* zero out observation table */
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(void)memset(obs, 0, sizeof(obs));
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for (nread = 0; nread < sizeof(inbuf); nread++) {
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if ((ch = getchar()) == EOF)
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break;
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inbuf[nread] = (unsigned char) ch;
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}
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for (i = 0; i < nread; i++)
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obs[inbuf[i]]++;
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/*
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* now "dot" the freqs with the observed letter freqs
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* and keep track of best fit
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*/
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winner = 0;
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winnerdot = 0.0;
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for (try = 0; try < LETTERS; try++) {
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dot = 0.0;
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for (i = 0; i < LETTERS; i++)
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dot += (obs[upper[i]] + obs[lower[i]])
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* stdf[(i + try) % LETTERS];
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if (try == 0 || dot > winnerdot) {
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/* got a new winner! */
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winner = try;
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winnerdot = dot;
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}
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}
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init_rottbl(winner);
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print_array(inbuf, nread);
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print_file();
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}
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int
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main(int argc, char **argv)
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{
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if (argc == 1) {
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guess_and_rotate();
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} else if (argc == 2) {
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init_rottbl(get_rotation(argv[1]));
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print_file();
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} else {
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(void)fprintf(stderr, "usage: caesar [rotation]\n");
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exit(EXIT_FAILURE);
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/* NOTREACHED */
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}
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if (ferror(stdin)) {
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errx(EXIT_FAILURE, "<stdin>");
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/* NOTREACHED */
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}
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(void)fflush(stdout);
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if (ferror(stdout)) {
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errx(EXIT_FAILURE, "<stdout>");
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/* NOTREACHED */
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}
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return 0;
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}
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