Add __attribute__((__noreturn__)) to various function prototypes in games/.
[dragonfly.git] / games / arithmetic / arithmetic.c
CommitLineData
6693db17 1/*-
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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 * Eamonn McManus of Trinity College Dublin.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
6693db17 16 * 3. Neither the name of the University nor the names of its contributors
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17 * may be used to endorse or promote products derived from this software
18 * without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
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31 *
32 * @(#) Copyright (c) 1989, 1993 The Regents of the University of California. All rights reserved.
33 * @(#)arithmetic.c 8.1 (Berkeley) 5/31/93
34 * $FreeBSD: src/games/arithmetic/arithmetic.c,v 1.10 1999/12/12 06:40:28 billf Exp $
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35 */
36
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37/*
38 * By Eamonn McManus, Trinity College Dublin <emcmanus@cs.tcd.ie>.
39 *
40 * The operation of this program mimics that of the standard Unix game
41 * `arithmetic'. I've made it as close as I could manage without examining
42 * the source code. The principal differences are:
43 *
44 * The method of biasing towards numbers that had wrong answers in the past
45 * is different; original `arithmetic' seems to retain the bias forever,
46 * whereas this program lets the bias gradually decay as it is used.
47 *
48 * Original `arithmetic' delays for some period (3 seconds?) after printing
49 * the score. I saw no reason for this delay, so I scrapped it.
50 *
51 * There is no longer a limitation on the maximum range that can be supplied
52 * to the program. The original program required it to be less than 100.
53 * Anomalous results may occur with this program if ranges big enough to
54 * allow overflow are given.
55 *
56 * I have obviously not attempted to duplicate bugs in the original. It
57 * would go into an infinite loop if invoked as `arithmetic / 0'. It also
58 * did not recognise an EOF in its input, and would continue trying to read
59 * after it. It did not check that the input was a valid number, treating any
60 * garbage as 0. Finally, it did not flush stdout after printing its prompt,
61 * so in the unlikely event that stdout was not a terminal, it would not work
62 * properly.
63 */
64
65#include <sys/types.h>
984263bc 66#include <ctype.h>
6693db17 67#include <signal.h>
984263bc 68#include <stdio.h>
984263bc 69#include <stdlib.h>
6693db17 70#include <string.h>
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71#include <time.h>
72#include <unistd.h>
73
2405d3a2 74static int getrandom(int, int, int);
09ac707a 75static void intr(int) __dead2;
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76static int opnum(int);
77static void penalise(int, int, int);
78static int problem(void);
79static void showstats(void);
09ac707a 80static void usage(void) __dead2;
6693db17 81
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82static const char keylist[] = "+-x/";
83static const char defaultkeys[] = "+-";
84static const char *keys = defaultkeys;
85static int nkeys = sizeof(defaultkeys) - 1;
86static int rangemax = 10;
87static int nright, nwrong;
88static time_t qtime;
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89#define NQUESTS 20
90
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91/*
92 * Select keys from +-x/ to be asked addition, subtraction, multiplication,
93 * and division problems. More than one key may be given. The default is
94 * +-. Specify a range to confine the operands to 0 - range. Default upper
95 * bound is 10. After every NQUESTS questions, statistics on the performance
96 * so far are printed.
97 */
98int
6693db17 99main(int argc, char *argv[])
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100{
101 int ch, cnt;
102
103 /* Revoke setgid privileges */
104 setgid(getgid());
105
106 while ((ch = getopt(argc, argv, "r:o:")) != -1)
107 switch(ch) {
108 case 'o': {
109 const char *p;
110
111 for (p = keys = optarg; *p; ++p)
112 if (!index(keylist, *p)) {
d9f85b33 113 fprintf(stderr,
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114 "arithmetic: unknown key.\n");
115 exit(1);
116 }
117 nkeys = p - optarg;
118 break;
119 }
120 case 'r':
121 if ((rangemax = atoi(optarg)) <= 0) {
d9f85b33 122 fprintf(stderr,
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123 "arithmetic: invalid range.\n");
124 exit(1);
125 }
126 break;
127 case '?':
128 default:
129 usage();
130 }
131 if (argc -= optind)
132 usage();
133
134 /* Seed the random-number generator. */
135 srandomdev();
136
d9f85b33 137 signal(SIGINT, intr);
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138
139 /* Now ask the questions. */
140 for (;;) {
141 for (cnt = NQUESTS; cnt--;)
142 if (problem() == EOF)
143 exit(0);
144 showstats();
145 }
146 /* NOTREACHED */
147}
148
149/* Handle interrupt character. Print score and exit. */
2405d3a2 150static void
e12c1abe 151intr(__unused int sig)
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152{
153 showstats();
154 exit(0);
155}
156
157/* Print score. Original `arithmetic' had a delay after printing it. */
2405d3a2 158static void
e12c1abe 159showstats(void)
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160{
161 if (nright + nwrong > 0) {
d9f85b33 162 printf("\n\nRights %d; Wrongs %d; Score %d%%",
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163 nright, nwrong, (int)(100L * nright / (nright + nwrong)));
164 if (nright > 0)
d9f85b33 165 printf("\nTotal time %ld seconds; %.1f seconds per problem\n\n",
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166 (long)qtime, (float)qtime / nright);
167 }
d9f85b33 168 printf("\n");
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169}
170
171/*
172 * Pick a problem and ask it. Keeps asking the same problem until supplied
173 * with the correct answer, or until EOF or interrupt is typed. Problems are
174 * selected such that the right operand and either the left operand (for +, x)
175 * or the correct result (for -, /) are in the range 0 to rangemax. Each wrong
176 * answer causes the numbers in the problem to be penalised, so that they are
177 * more likely to appear in subsequent problems.
178 */
2405d3a2 179static int
e12c1abe 180problem(void)
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181{
182 char *p;
183 time_t start, finish;
184 int left, op, right, result;
185 char line[80];
186
187 left = 0;
188 right = 0;
189 result = 0;
190 op = keys[random() % nkeys];
191 if (op != '/')
192 right = getrandom(rangemax + 1, op, 1);
193retry:
194 /* Get the operands. */
195 switch (op) {
196 case '+':
197 left = getrandom(rangemax + 1, op, 0);
198 result = left + right;
199 break;
200 case '-':
201 result = getrandom(rangemax + 1, op, 0);
202 left = right + result;
203 break;
204 case 'x':
205 left = getrandom(rangemax + 1, op, 0);
206 result = left * right;
207 break;
208 case '/':
209 right = getrandom(rangemax, op, 1) + 1;
210 result = getrandom(rangemax + 1, op, 0);
211 left = right * result + random() % right;
212 break;
213 }
214
215 /*
216 * A very big maxrange could cause negative values to pop
217 * up, owing to overflow.
218 */
219 if (result < 0 || left < 0)
220 goto retry;
221
d9f85b33 222 printf("%d %c %d = ", left, op, right);
223 fflush(stdout);
224 time(&start);
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225
226 /*
227 * Keep looping until the correct answer is given, or until EOF or
228 * interrupt is typed.
229 */
230 for (;;) {
231 if (!fgets(line, sizeof(line), stdin)) {
d9f85b33 232 printf("\n");
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233 return(EOF);
234 }
235 for (p = line; *p && isspace(*p); ++p);
236 if (!isdigit(*p)) {
d9f85b33 237 printf("Please type a number.\n");
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238 continue;
239 }
240 if (atoi(p) == result) {
d9f85b33 241 printf("Right!\n");
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242 ++nright;
243 break;
244 }
245 /* Wrong answer; penalise and ask again. */
d9f85b33 246 printf("What?\n");
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247 ++nwrong;
248 penalise(right, op, 1);
249 if (op == 'x' || op == '+')
250 penalise(left, op, 0);
251 else
252 penalise(result, op, 0);
253 }
254
255 /*
256 * Accumulate the time taken. Obviously rounding errors happen here;
257 * however they should cancel out, because some of the time you are
258 * charged for a partially elapsed second at the start, and some of
259 * the time you are not charged for a partially elapsed second at the
260 * end.
261 */
d9f85b33 262 time(&finish);
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263 qtime += finish - start;
264 return(0);
265}
266
267/*
268 * Here is the code for accumulating penalties against the numbers for which
269 * a wrong answer was given. The right operand and either the left operand
270 * (for +, x) or the result (for -, /) are stored in a list for the particular
271 * operation, and each becomes more likely to appear again in that operation.
272 * Initially, each number is charged a penalty of WRONGPENALTY, giving it that
273 * many extra chances of appearing. Each time it is selected because of this,
274 * its penalty is decreased by one; it is removed when it reaches 0.
275 *
276 * The penalty[] array gives the sum of all penalties in the list for
277 * each operation and each operand. The penlist[] array has the lists of
278 * penalties themselves.
279 */
280
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281static int penalty[sizeof(keylist) - 1][2];
282static struct penalty {
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283 int value, penalty; /* Penalised value and its penalty. */
284 struct penalty *next;
285} *penlist[sizeof(keylist) - 1][2];
286
287#define WRONGPENALTY 5 /* Perhaps this should depend on maxrange. */
288
289/*
290 * Add a penalty for the number `value' to the list for operation `op',
291 * operand number `operand' (0 or 1). If we run out of memory, we just
292 * forget about the penalty (how likely is this, anyway?).
293 */
2405d3a2 294static void
e12c1abe 295penalise(int value, int op, int operand)
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296{
297 struct penalty *p;
298
299 op = opnum(op);
6693db17 300 if ((p = malloc(sizeof(*p))) == NULL)
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301 return;
302 p->next = penlist[op][operand];
303 penlist[op][operand] = p;
304 penalty[op][operand] += p->penalty = WRONGPENALTY;
305 p->value = value;
306}
307
308/*
309 * Select a random value from 0 to maxval - 1 for operand `operand' (0 or 1)
310 * of operation `op'. The random number we generate is either used directly
311 * as a value, or represents a position in the penalty list. If the latter,
312 * we find the corresponding value and return that, decreasing its penalty.
313 */
2405d3a2 314static int
e12c1abe 315getrandom(int maxval, int op, int operand)
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316{
317 int value;
318 struct penalty **pp, *p;
319
320 op = opnum(op);
321 value = random() % (maxval + penalty[op][operand]);
322
323 /*
324 * 0 to maxval - 1 is a number to be used directly; bigger values
325 * are positions to be located in the penalty list.
326 */
327 if (value < maxval)
328 return(value);
329 value -= maxval;
330
331 /*
332 * Find the penalty at position `value'; decrement its penalty and
333 * delete it if it reaches 0; return the corresponding value.
334 */
335 for (pp = &penlist[op][operand]; (p = *pp) != NULL; pp = &p->next) {
336 if (p->penalty > value) {
337 value = p->value;
338 penalty[op][operand]--;
339 if (--(p->penalty) <= 0) {
340 p = p->next;
d9f85b33 341 free((char *)*pp);
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342 *pp = p;
343 }
344 return(value);
345 }
346 value -= p->penalty;
347 }
348 /*
349 * We can only get here if the value from the penalty[] array doesn't
350 * correspond to the actual sum of penalties in the list. Provide an
351 * obscure message.
352 */
d9f85b33 353 fprintf(stderr, "arithmetic: bug: inconsistent penalties\n");
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354 exit(1);
355 /* NOTREACHED */
356}
357
358/* Return an index for the character op, which is one of [+-x/]. */
2405d3a2 359static int
e12c1abe 360opnum(int op)
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361{
362 char *p;
363
364 if (op == 0 || (p = index(keylist, op)) == NULL) {
d9f85b33 365 fprintf(stderr,
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366 "arithmetic: bug: op %c not in keylist %s\n", op, keylist);
367 exit(1);
368 }
369 return(p - keylist);
370}
371
372/* Print usage message and quit. */
373static void
e12c1abe 374usage(void)
984263bc 375{
d9f85b33 376 fprintf(stderr, "usage: arithmetic [-o +-x/] [-r range]\n");
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377 exit(1);
378}