Make this compile with gcc40: rename variables so that they don't collide
[dragonfly.git] / games / caesar / caesar.c
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1/*
2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California. All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Rick Adams.
7 *
8 * Authors:
9 * Stan King, John Eldridge, based on algorithm suggested by
10 * Bob Morris
11 * 29-Sep-82
12 *
13 * Redistribution and use in source and binary forms, with or without
14 * modification, are permitted provided that the following conditions
15 * are met:
16 * 1. Redistributions of source code must retain the above copyright
17 * notice, this list of conditions and the following disclaimer.
18 * 2. Redistributions in binary form must reproduce the above copyright
19 * notice, this list of conditions and the following disclaimer in the
20 * documentation and/or other materials provided with the distribution.
21 * 3. All advertising materials mentioning features or use of this software
22 * must display the following acknowledgement:
23 * This product includes software developed by the University of
24 * California, Berkeley and its contributors.
25 * 4. Neither the name of the University nor the names of its contributors
26 * may be used to endorse or promote products derived from this software
27 * without specific prior written permission.
28 *
29 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
30 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
31 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
32 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
33 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
34 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
35 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
36 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
37 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
38 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 * SUCH DAMAGE.
40 *
41 * $FreeBSD: src/games/caesar/caesar.c,v 1.8.2.1 2000/08/17 06:13:06 jhb Exp $
da83aa48 42 * $DragonFly: src/games/caesar/caesar.c,v 1.4 2005/03/01 22:47:10 joerg Exp $
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43 *
44 * @(#) Copyright (c) 1989, 1993 The Regents of the University of California. All rights reserved.
45 * @(#)caesar.c 8.1 (Berkeley) 5/31/93
46 * $FreeBSD: src/games/caesar/caesar.c,v 1.8.2.1 2000/08/17 06:13:06 jhb Exp $
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47 */
48
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49#include <ctype.h>
50#include <err.h>
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51#include <errno.h>
52#include <math.h>
53#include <stdio.h>
54#include <stdlib.h>
55#include <string.h>
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56#include <unistd.h>
57
58#define LINELENGTH 2048
59#define ROTATE(ch, perm) \
60 isascii(ch) ? ( \
61 isupper(ch) ? ('A' + (ch - 'A' + perm) % 26) : \
62 islower(ch) ? ('a' + (ch - 'a' + perm) % 26) : ch) : ch
63
64/*
65 * letter frequencies (taken from some unix(tm) documentation)
66 * (unix is a trademark of Bell Laboratories)
67 */
da83aa48 68static double stdf[26] = {
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69 7.97, 1.35, 3.61, 4.78, 12.37, 2.01, 1.46, 4.49, 6.39, 0.04,
70 0.42, 3.81, 2.69, 5.92, 6.96, 2.91, 0.08, 6.63, 8.77, 9.68,
71 2.62, 0.81, 1.88, 0.23, 2.07, 0.06,
72};
73
da83aa48 74static void printit(const char *);
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75
76int
da83aa48 77main(int argc, char **argv)
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78{
79 int ch, dot, i, nread, winnerdot = 0;
80 char *inbuf;
81 int obs[26], try, winner;
82
83 /* revoke setgid privileges */
84 setgid(getgid());
85
86 if (argc > 1)
87 printit(argv[1]);
88
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89 if ((inbuf = malloc(LINELENGTH)) == NULL)
90 err(1, "malloc failed");
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91
92 /* adjust frequency table to weight low probs REAL low */
93 for (i = 0; i < 26; ++i)
94 stdf[i] = log(stdf[i]) + log(26.0 / 100.0);
95
96 /* zero out observation table */
97 bzero(obs, 26 * sizeof(int));
98
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99 if ((nread = read(STDIN_FILENO, inbuf, LINELENGTH)) < 0)
100 err(1, "read failed");
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101 for (i = nread; i--;) {
102 ch = (unsigned char) inbuf[i];
103 if (isascii(ch)) {
104 if (islower(ch))
105 ++obs[ch - 'a'];
106 else if (isupper(ch))
107 ++obs[ch - 'A'];
108 }
109 }
110
111 /*
112 * now "dot" the freqs with the observed letter freqs
113 * and keep track of best fit
114 */
115 for (try = winner = 0; try < 26; ++try) { /* += 13) { */
116 dot = 0;
117 for (i = 0; i < 26; i++)
118 dot += obs[i] * stdf[(i + try) % 26];
119 /* initialize winning score */
120 if (try == 0)
121 winnerdot = dot;
122 if (dot > winnerdot) {
123 /* got a new winner! */
124 winner = try;
125 winnerdot = dot;
126 }
127 }
128
129 for (;;) {
130 for (i = 0; i < nread; ++i) {
131 ch = (unsigned char) inbuf[i];
132 putchar(ROTATE(ch, winner));
133 }
134 if (nread < LINELENGTH)
135 break;
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136 if ((nread = read(STDIN_FILENO, inbuf, LINELENGTH)) < 0)
137 err(1, "read failed");
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138 }
139 exit(0);
140}
141
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142static void
143printit(const char *arg)
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144{
145 int ch, rot;
146
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147 if ((rot = atoi(arg)) < 0)
148 errx(1, "bad rotation value");
149
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150 while ((ch = getchar()) != EOF)
151 putchar(ROTATE(ch, rot));
152 exit(0);
153}