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0b8224d1cc
We've ifdef'd out the copyright strings for some time now. Go ahead and remove the ifdefs. Plus whatever other detritis was left over from other recent removals. These copyright strings are present in the comments and are largely from CSRG's attempt at adding their copyright to every binary file (which modern interpretations of the license doesn't require). Sponsored by: Netflix
146 lines
4.1 KiB
C
146 lines
4.1 KiB
C
/*
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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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*
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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 <errno.h>
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#include <math.h>
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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 <ctype.h>
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#include <unistd.h>
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#define LINELENGTH 2048
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#define ROTATE(ch, perm) \
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isascii(ch) ? ( \
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isupper(ch) ? ('A' + (ch - 'A' + perm) % 26) : \
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islower(ch) ? ('a' + (ch - 'a' + perm) % 26) : ch) : ch
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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 double stdf[26] = {
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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 void printit(char *);
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int
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main(int argc, char **argv)
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{
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int ch, dot, i, nread, winnerdot = 0;
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char *inbuf;
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int obs[26], try, winner;
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if (argc > 1)
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printit(argv[1]);
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if (!(inbuf = malloc((size_t)LINELENGTH))) {
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(void)fprintf(stderr, "caesar: out of memory.\n");
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exit(1);
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}
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/* adjust frequency table to weight low probs REAL low */
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for (i = 0; i < 26; ++i)
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stdf[i] = log(stdf[i]) + log(26.0 / 100.0);
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/* zero out observation table */
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bzero(obs, 26 * sizeof(int));
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if ((nread = read(STDIN_FILENO, inbuf, (size_t)LINELENGTH)) < 0) {
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(void)fprintf(stderr, "caesar: %s\n", strerror(errno));
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exit(1);
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}
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for (i = nread; i--;) {
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ch = (unsigned char) inbuf[i];
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if (isascii(ch)) {
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if (islower(ch))
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++obs[ch - 'a'];
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else if (isupper(ch))
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++obs[ch - 'A'];
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}
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}
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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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for (try = winner = 0; try < 26; ++try) { /* += 13) { */
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dot = 0;
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for (i = 0; i < 26; i++)
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dot += obs[i] * stdf[(i + try) % 26];
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/* initialize winning score */
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if (try == 0)
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winnerdot = dot;
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if (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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for (;;) {
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for (i = 0; i < nread; ++i) {
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ch = (unsigned char) inbuf[i];
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putchar(ROTATE(ch, winner));
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}
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if (nread < LINELENGTH)
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break;
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if ((nread = read(STDIN_FILENO, inbuf, (size_t)LINELENGTH)) < 0) {
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(void)fprintf(stderr, "caesar: %s\n", strerror(errno));
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exit(1);
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}
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}
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exit(0);
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}
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static void
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printit(char *arg)
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{
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int ch, rot;
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if ((rot = atoi(arg)) < 0) {
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(void)fprintf(stderr, "caesar: bad rotation value.\n");
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exit(1);
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}
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while ((ch = getchar()) != EOF)
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putchar(ROTATE(ch, rot));
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exit(0);
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}
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