xref: /freebsd/usr.bin/ncal/ncal.c (revision 4cf49a43559ed9fdad601bdcccd2c55963008675)
1 /*-
2  * Copyright (c) 1997 Wolfgang Helbig
3  * All rights reserved.
4  *
5  * Redistribution and use in source and binary forms, with or without
6  * modification, are permitted provided that the following conditions
7  * are met:
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  *
14  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24  * SUCH DAMAGE.
25  */
26 
27 #ifndef lint
28 static const char rcsid[] =
29   "$FreeBSD$";
30 #endif /* not lint */
31 
32 #include <calendar.h>
33 #include <err.h>
34 #include <locale.h>
35 #include <stdio.h>
36 #include <stdlib.h>
37 #include <string.h>
38 #include <sysexits.h>
39 #include <time.h>
40 #include <unistd.h>
41 
42 /* Width of one month with backward compatibility */
43 #define MONTH_WIDTH_B_J 27
44 #define MONTH_WIDTH_B 20
45 
46 #define MONTH_WIDTH_J 24
47 #define MONTH_WIDTH 18
48 
49 #define MAX_WIDTH 28
50 
51 typedef struct date date;
52 
53 struct monthlines {
54 	char name[MAX_WIDTH + 1];
55 	char lines[7][MAX_WIDTH + 1];
56 	char weeks[MAX_WIDTH + 1];
57 };
58 
59 struct weekdays {
60 	char names[7][4];
61 };
62 
63 /* The switches from Julian to Gregorian in some countries */
64 static struct djswitch {
65 	char *cc;	/* Country code according to ISO 3166 */
66 	char *nm;	/* Name of country */
67 	date dt;	/* Last day of Julian calendar */
68 	char *efmt;	/* strftime format for printing date of easter */
69 } switches[] = {
70 	{"AL", "Albania",	{1912, 11, 30}, "%e %B %Y"},
71 	{"AT", "Austria",	{1583, 10,  5}, "%e. %B %Y"},
72 	{"AU", "Australia",	{1752,  9,  2}, "%B %e, %Y"},
73 	{"BE", "Belgium",	{1582, 12, 14}, "%B %e, %Y"},
74 	{"BG", "Bulgaria",	{1916,  3, 18}, "%e %B %Y"},
75 	{"CA", "Canada",	{1752,  9,  2}, "%B %e, %Y"},
76 	{"CH", "Switzerland",	{1655,  2, 28}, "%e. %B %Y"},
77 	{"CN", "China",		{1911, 12, 18}, "%e %B %Y"},
78 	{"CZ", "Czech Republic",{1584,  1,  6}, "%e %B %Y"},
79 	{"DE", "Germany",	{1700,  2, 18}, "%e. %B %Y"},
80 	{"DK", "Denmark",	{1700,  2, 18}, "%e. %B %Y"},
81 	{"ES", "Spain",		{1582, 10,  4}, "%e de %B de %Y"},
82 	{"FI", "Finland",	{1753,  2, 17}, "%e %B %Y"},
83 	{"FR", "France",	{1582, 12,  9}, "%e. %B %Y"},
84 	{"GB", "United Kingdom",{1752,  9,  2}, "%e %B %Y"},
85 	{"GR", "Greece",	{1924,  3,  9}, "%e %B %Y"},
86 	{"HU", "Hungary",	{1587, 10, 21}, "%e %B %Y"},
87 	{"IS", "Iceland",	{1700, 11, 16}, "%e %B %Y"},
88 	{"IT", "Italy",		{1582, 10,  4}, "%e %B %Y"},
89 	{"JP", "Japan",		{1918, 12, 18}, "%Y\x94N %B%e"},
90 	{"LI", "Lithuania",	{1918,  2,  1}, "%e %B %Y"},
91 	{"LN", "Latin",		{9999, 05, 31}, "%e %B %Y"},
92 	{"LU", "Luxembourg",	{1582, 12, 14}, "%e %B %Y"},
93 	{"LV", "Latvia",	{1918,  2,  1}, "%e %B %Y"},
94 	{"NL", "Netherlands",	{1582, 12, 14}, "%e %B %Y"},
95 	{"NO", "Norway",	{1700,  2, 18}, "%e %B %Y"},
96 	{"PL", "Poland",	{1582, 10,  4}, "%e %B %Y"},
97 	{"PT", "Portugal",	{1582, 10,  4}, "%e %B %Y"},
98 	{"RO", "Romania",	{1919,  3, 31}, "%e %B %Y"},
99 	{"RU", "Russia",	{1918,  1, 31}, "%e %B %Y"},
100 	{"SI", "Slovenia",	{1919,  3,  4}, "%e %B %Y"},
101 	{"SU", "USSR",		{1920,  3,  4}, "%e %B %Y"},
102 	{"SW", "Sweden",	{1753,  2, 17}, "%e %B %Y"},
103 	{"TR", "Turkey",	{1926, 12, 18}, "%e %B %Y"},
104 	{"US", "United States",	{1752,  9,  2}, "%B %e, %Y"},
105 	{"YU", "Yugoslavia",	{1919,  3,  4}, "%e %B %Y"}
106 };
107 
108 struct djswitch *dftswitch =
109     switches + sizeof(switches) / sizeof(struct djswitch) - 2;
110     /* default switch (should be "US") */
111 
112 /* Table used to print day of month and week numbers */
113 char daystr[] = "     1  2  3  4  5  6  7  8  9 10 11 12 13 14 15"
114 		" 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31"
115 		" 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47"
116 		" 48 49 50 51 52 53";
117 
118 /* Table used to print day of year and week numbers */
119 char jdaystr[] = "       1   2   3   4   5   6   7   8   9"
120 		 "  10  11  12  13  14  15  16  17  18  19"
121 		 "  20  21  22  23  24  25  26  27  28  29"
122 		 "  30  31  32  33  34  35  36  37  38  39"
123 		 "  40  41  42  43  44  45  46  47  48  49"
124 		 "  50  51  52  53  54  55  56  57  58  59"
125 		 "  60  61  62  63  64  65  66  67  68  69"
126 		 "  70  71  72  73  74  75  76  77  78  79"
127 		 "  80  81  82  83  84  85  86  87  88  89"
128 		 "  90  91  92  93  94  95  96  97  98  99"
129 		 " 100 101 102 103 104 105 106 107 108 109"
130 		 " 110 111 112 113 114 115 116 117 118 119"
131 		 " 120 121 122 123 124 125 126 127 128 129"
132 		 " 130 131 132 133 134 135 136 137 138 139"
133 		 " 140 141 142 143 144 145 146 147 148 149"
134 		 " 150 151 152 153 154 155 156 157 158 159"
135 		 " 160 161 162 163 164 165 166 167 168 169"
136 		 " 170 171 172 173 174 175 176 177 178 179"
137 		 " 180 181 182 183 184 185 186 187 188 189"
138 		 " 190 191 192 193 194 195 196 197 198 199"
139 		 " 200 201 202 203 204 205 206 207 208 209"
140 		 " 210 211 212 213 214 215 216 217 218 219"
141 		 " 220 221 222 223 224 225 226 227 228 229"
142 		 " 230 231 232 233 234 235 236 237 238 239"
143 		 " 240 241 242 243 244 245 246 247 248 249"
144 		 " 250 251 252 253 254 255 256 257 258 259"
145 		 " 260 261 262 263 264 265 266 267 268 269"
146 		 " 270 271 272 273 274 275 276 277 278 279"
147 		 " 280 281 282 283 284 285 286 287 288 289"
148 		 " 290 291 292 293 294 295 296 297 298 299"
149 		 " 300 301 302 303 304 305 306 307 308 309"
150 		 " 310 311 312 313 314 315 316 317 318 319"
151 		 " 320 321 322 323 324 325 326 327 328 329"
152 		 " 330 331 332 333 334 335 336 337 338 339"
153 		 " 340 341 342 343 344 345 346 347 348 349"
154 		 " 350 351 352 353 354 355 356 357 358 359"
155 		 " 360 361 362 363 364 365 366";
156 
157 int     flag_weeks;		/* user wants number of week */
158 int     nswitch;		/* user defined switch date */
159 int	nswitchb;		/* switch date for backward compatibility */
160 char   *efmt;			/* strftime format string for printeaster() */
161 
162 char   *center(char *s, char *t, int w);
163 void	mkmonth(int year, int month, int jd_flag, struct monthlines * monthl);
164 void    mkmonthb(int year, int month, int jd_flag, struct monthlines * monthl);
165 void    mkweekdays(struct weekdays * wds);
166 void    printcc(void);
167 void    printeaster(int year, int julian, int orthodox);
168 void    printmonth(int year, int month, int jd_flag);
169 void    printmonthb(int year, int month, int jd_flag);
170 void    printyear(int year, int jd_flag);
171 void    printyearb(int year, int jd_flag);
172 int	firstday(int y, int m);
173 date   *sdate(int ndays, struct date * d);
174 date   *sdateb(int ndays, struct date * d);
175 int     sndays(struct date * d);
176 int     sndaysb(struct date * d);
177 static void usage(void);
178 int     weekdayb(int nd);
179 
180 int
181 main(int argc, char *argv[])
182 {
183 	struct  djswitch *p, *q;	/* to search user defined switch date */
184 	date	never = {10000, 1, 1};	/* outside valid range of dates */
185 	date	ukswitch = {1752, 9, 2};/* switch date for Great Britain */
186 	int     ch;			/* holds the option character */
187 	int     m = 0;			/* month */
188 	int	y = 0;			/* year */
189 	int     flag_backward = 0;	/* user called cal--backward compat. */
190 	int     flag_hole_year = 0;	/* user wants the whole year */
191 	int	flag_julian_cal = 0;	/* user wants Julian Calendar */
192 	int     flag_julian_day = 0;	/* user wants the Julian day
193 					 * numbers */
194 	int	flag_orthodox = 0;	/* use wants Orthodox easter */
195 	int	flag_easter = 0;	/* use wants easter date */
196 	char	*cp;			/* character pointer */
197 	char    *locale;		/* locale to get country code */
198 
199 	/*
200 	 * Use locale to determine the country code,
201 	 * and use the country code to determine the default
202 	 * switchdate and date format from the switches table.
203 	 */
204 	if ((locale = setlocale(LC_TIME, "")) == NULL)
205 		warn("setlocale");
206 	if (locale == NULL || locale == "C")
207 		locale = "_US";
208 	q = switches + sizeof(switches) / sizeof(struct djswitch);
209 	for (p = switches; p != q; p++)
210 		if ((cp = strstr(locale, p->cc)) != NULL && *(cp - 1) == '_')
211 			break;
212 	if (p == q) {
213 		nswitch = ndaysj(&dftswitch->dt);
214 		efmt = dftswitch->efmt;
215 	} else {
216 		nswitch = ndaysj(&p->dt);
217 		efmt = p->efmt;
218 		dftswitch = p;
219 	}
220 
221 
222 	/*
223 	 * Get the filename portion of argv[0] and set flag_backward if
224 	 * this program is called "cal".
225 	 */
226 	for (cp = argv[0]; *cp; cp++)
227 		;
228 	while (cp >= argv[0] && *cp != '/')
229 		cp--;
230 	if (strcmp("cal", ++cp) == 0)
231 		flag_backward = 1;
232 
233 	/* Set the switch date to United Kingdom if backwards compatible */
234 	if (flag_backward)
235 		nswitchb = ndaysj(&ukswitch);
236 
237 	while ((ch = getopt(argc, argv, "Jejops:wy")) != -1)
238 		switch (ch) {
239 		case 'J':
240 			if (flag_backward)
241 				usage();
242 			nswitch = ndaysj(&never);
243 			flag_julian_cal = 1;
244 			break;
245 		case 'e':
246 			if (flag_backward)
247 				usage();
248 			flag_easter = 1;
249 			break;
250 		case 'j':
251 			flag_julian_day = 1;
252 			break;
253 		case 'o':
254 			if (flag_backward)
255 				usage();
256 			flag_orthodox = 1;
257 			flag_easter = 1;
258 			break;
259 		case 'p':
260 			if (flag_backward)
261 				usage();
262 			printcc();
263 			return (0);
264 			break;
265 		case 's':
266 			if (flag_backward)
267 				usage();
268 			q = switches +
269 			    sizeof(switches) / sizeof(struct djswitch);
270 			for (p = switches;
271 			     p != q && strcmp(p->cc, optarg) != 0; p++)
272 				;
273 			if (p == q)
274 				errx(EX_USAGE,
275 				    "%s: invalid country code", optarg);
276 			nswitch = ndaysj(&(p->dt));
277 			break;
278 		case 'w':
279 			if (flag_backward)
280 				usage();
281 			flag_weeks = 1;
282 			break;
283 		case 'y':
284 			flag_hole_year = 1;
285 			break;
286 		default:
287 			usage();
288 		}
289 
290 	argc -= optind;
291 	argv += optind;
292 
293 	if (argc == 0) {
294 		time_t t;
295 		struct tm *tm;
296 
297 		t = time(NULL);
298 		tm = localtime(&t);
299 		y = tm->tm_year + 1900;
300 		m = tm->tm_mon + 1;
301 	}
302 
303 	switch (argc) {
304 	case 2:
305 		if (flag_easter)
306 			usage();
307 		m = atoi(*argv++);
308 		if (m < 1 || m > 12)
309 			errx(EX_USAGE, "month %d not in range 1..12", m);
310 		/* FALLTHROUGH */
311 	case 1:
312 		y = atoi(*argv++);
313 		if (y < 1 || y > 9999)
314 			errx(EX_USAGE, "year %d not in range 1..9999", y);
315 		break;
316 	case 0:
317 		break;
318 	default:
319 		usage();
320 	}
321 
322 	if (flag_easter)
323 		printeaster(y, flag_julian_cal, flag_orthodox);
324 	else if (argc == 1 || flag_hole_year)
325 		if (flag_backward)
326 			printyearb(y, flag_julian_day);
327 		else
328 			printyear(y, flag_julian_day);
329 	else
330 		if (flag_backward)
331 			printmonthb(y, m, flag_julian_day);
332 		else
333 			printmonth(y, m, flag_julian_day);
334 
335 	return (0);
336 }
337 
338 static void
339 usage(void)
340 {
341 
342 	fprintf(stderr, "%s\n%s\n%s\n",
343 	    "usage: cal [-jy] [[month] year]",
344 	    "       ncal [-Jjpwy] [-s country_code] [[month] year]",
345 	    "       ncal [-Jeo] [year]");
346 	exit(EX_USAGE);
347 }
348 
349 /* print the assumed switches for all countries */
350 void
351 printcc(void)
352 {
353 	struct djswitch *p;
354 	int n;	/* number of lines to print */
355 	int m;	/* offset from left to right table entry on the same line */
356 
357 #define FSTR "%c%s %-15s%4d-%02d-%02d"
358 #define DFLT(p) ((p) == dftswitch ? '*' : ' ')
359 #define FSTRARG(p) DFLT(p), (p)->cc, (p)->nm, (p)->dt.y, (p)->dt.m, (p)->dt.d
360 
361 	n = sizeof(switches) / sizeof(struct djswitch);
362 	m = (n + 1) / 2;
363 	n /= 2;
364 	for (p = switches; p != switches + n; p++)
365 		printf(FSTR"     "FSTR"\n", FSTRARG(p), FSTRARG(p+m));
366 	if (m != n)
367 		printf(FSTR"\n", FSTRARG(p));
368 }
369 
370 /* print the date of easter sunday */
371 void
372 printeaster(int y, int julian, int orthodox)
373 {
374 	date    dt;
375 	struct tm tm;
376 	char    buf[80];
377 
378 	/* force orthodox easter for years before 1583 */
379 	if (y < 1583)
380 		orthodox = 1;
381 
382 	if (orthodox)
383 		if (julian)
384 			easteroj(y, &dt);
385 		else
386 			easterog(y, &dt);
387 	else
388 		easterg(y, &dt);
389 
390 	memset(&tm, 0, sizeof(tm));
391 	tm.tm_year = dt.y - 1900;
392 	tm.tm_mon  = dt.m - 1;
393 	tm.tm_mday = dt.d;
394 	strftime(buf, sizeof(buf), efmt,  &tm);
395 	printf("%s\n", buf);
396 }
397 
398 void
399 printmonth(int y, int m, int jd_flag)
400 {
401 	struct monthlines month;
402 	struct weekdays wds;
403 	int i;
404 
405 	mkmonth(y, m - 1, jd_flag, &month);
406 	mkweekdays(&wds);
407 	printf("    %s %d\n", month.name, y);
408 	for (i = 0; i != 7; i++)
409 		printf("%.2s%s\n", wds.names[i], month.lines[i]);
410 	if (flag_weeks)
411 		printf("  %s\n", month.weeks);
412 }
413 
414 void
415 printmonthb(int y, int m, int jd_flag)
416 {
417 	struct monthlines month;
418 	struct weekdays wds;
419 	char s[MAX_WIDTH], t[MAX_WIDTH];
420 	int i;
421 	int mw;
422 
423 	mkmonthb(y, m - 1, jd_flag, &month);
424 	mkweekdays(&wds);
425 
426 	mw = jd_flag ? MONTH_WIDTH_B_J : MONTH_WIDTH_B;
427 
428 	sprintf(s, "%s %d", month.name, y);
429 	printf("%s\n", center(t, s, mw));
430 
431 	if (jd_flag)
432 		printf(" %s %s %s %s %s %s %.2s\n", wds.names[6], wds.names[0],
433 			wds.names[1], wds.names[2], wds.names[3],
434 			wds.names[4], wds.names[5]);
435 	else
436 		printf("%s%s%s%s%s%s%.2s\n", wds.names[6], wds.names[0],
437 			wds.names[1], wds.names[2], wds.names[3],
438 			wds.names[4], wds.names[5]);
439 
440 	for (i = 0; i != 6; i++)
441 		printf("%s\n", month.lines[i]+1);
442 }
443 
444 void
445 printyear(int y, int jd_flag)
446 {
447 	struct monthlines year[12];
448 	struct weekdays wds;
449 	char    s[80], t[80];
450 	int     i, j;
451 	int     mpl;
452 	int     mw;
453 
454 	for (i = 0; i != 12; i++)
455 		mkmonth(y, i, jd_flag, year + i);
456 	mkweekdays(&wds);
457 	mpl = jd_flag ? 3 : 4;
458 	mw = jd_flag ? MONTH_WIDTH_J : MONTH_WIDTH;
459 
460 	sprintf(s, "%d", y);
461 	printf("%s\n", center(t, s, mpl * mw));
462 
463 	for (j = 0; j != 12; j += mpl) {
464 		printf("    %-*s%-*s",
465 		    mw, year[j].name,
466 		    mw, year[j + 1].name);
467 		if (mpl == 3)
468 			printf("%s\n", year[j + 2].name);
469 		else
470 			printf("%-*s%s\n",
471 		    	    mw, year[j + 2].name,
472 		    	    year[j + 3].name);
473 		for (i = 0; i != 7; i++) {
474 			printf("%.2s%-*s%-*s",
475 			    wds.names[i],
476 			    mw, year[j].lines[i],
477 			    mw, year[j + 1].lines[i]);
478 			if (mpl == 3)
479 				printf("%s\n", year[j + 2].lines[i]);
480 			else
481 				printf("%-*s%s\n",
482 			    	    mw, year[j + 2].lines[i],
483 			    	    year[j + 3].lines[i]);
484 		}
485 		if (flag_weeks) {
486 			if (mpl == 3)
487 				printf("  %-*s%-*s%-s\n",
488 				    mw, year[j].weeks,
489 				    mw, year[j + 1].weeks,
490 				    year[j + 2].weeks);
491 			else
492 				printf("  %-*s%-*s%-*s%-s\n",
493 				    mw, year[j].weeks,
494 				    mw, year[j + 1].weeks,
495 				    mw, year[j + 2].weeks,
496 				    year[j + 3].weeks);
497 		}
498 	}
499 }
500 
501 void
502 printyearb(int y, int jd_flag)
503 {
504 	struct monthlines year[12];
505 	struct weekdays wds;
506 	char	s[80], t[80];
507 	int     i, j;
508 	int     mpl;
509 	int     mw;
510 
511 	for (i = 0; i != 12; i++)
512 		mkmonthb(y, i, jd_flag, year + i);
513 	mkweekdays(&wds);
514 	mpl = jd_flag ? 2 : 3;
515 	mw = jd_flag ? MONTH_WIDTH_B_J : MONTH_WIDTH_B;
516 
517 	sprintf(s, "%d", y);
518 	printf("%s\n\n", center(t, s, mw * mpl + mpl));
519 
520 	for (j = 0; j != 12; j += mpl) {
521 		printf("%-*s  ", mw, center(s, year[j].name, mw));
522 		if (mpl == 2)
523 			printf("%s\n", center(s, year[j + 1].name, mw));
524 		else
525 			printf("%-*s  %s\n", mw,
526 			    center(s, year[j + 1].name, mw),
527 			    center(t, year[j + 2].name, mw));
528 
529 		if (mpl == 2)
530 			printf(" %s %s %s %s %s %s %s "
531 			       " %s %s %s %s %s %s %.2s\n",
532 				wds.names[6], wds.names[0], wds.names[1],
533 				wds.names[2], wds.names[3], wds.names[4],
534 				wds.names[5],
535 				wds.names[6], wds.names[0], wds.names[1],
536 				wds.names[2], wds.names[3], wds.names[4],
537 				wds.names[5]);
538 		else
539 			printf("%s%s%s%s%s%s%s "
540 				"%s%s%s%s%s%s%s "
541 				"%s%s%s%s%s%s%.2s\n",
542 				wds.names[6], wds.names[0], wds.names[1],
543 				wds.names[2], wds.names[3], wds.names[4],
544 				wds.names[5],
545 				wds.names[6], wds.names[0], wds.names[1],
546 				wds.names[2], wds.names[3], wds.names[4],
547 				wds.names[5],
548 				wds.names[6], wds.names[0], wds.names[1],
549 				wds.names[2], wds.names[3], wds.names[4],
550 				wds.names[5]);
551 		for (i = 0; i != 6; i++) {
552 			if (mpl == 2)
553 				printf("%-*s  %s\n",
554 			    mw, year[j].lines[i]+1,
555 			    year[j + 1].lines[i]+1);
556 			else
557 				printf("%-*s  %-*s  %s\n",
558 			    mw, year[j].lines[i]+1,
559 			    mw, year[j + 1].lines[i]+1,
560 			    year[j + 2].lines[i]+1);
561 
562 		}
563 	}
564 }
565 
566 void
567 mkmonth(int y, int m, int jd_flag, struct monthlines *mlines)
568 {
569 
570 	struct tm tm;		/* for strftime printing local names of
571 				 * months */
572 	date    dt;		/* handy date */
573 	int     dw;		/* width of numbers */
574 	int     first;		/* first day of month */
575 	int     firstm;		/* first day of first week of month */
576 	int     i, j, k;	/* just indices */
577 	int     last;		/* the first day of next month */
578 	int     jan1 = 0;	/* the first day of this year */
579 	char   *ds;		/* pointer to day strings (daystr or
580 				 * jdaystr) */
581 
582 	/* Set name of month. */
583 	memset(&tm, 0, sizeof(tm));
584 	tm.tm_mon = m;
585 	strftime(mlines->name, sizeof(mlines->name), "%OB", &tm);
586 
587 	/*
588 	 * Set first and last to the day number of the first day of this
589 	 * month and the first day of next month respectively. Set jan1 to
590 	 * the day number of the first day of this year.
591 	 */
592 	first = firstday(y, m + 1);
593 	if (m == 11)
594 		last = firstday(y + 1, 1);
595 	else
596 		last = firstday(y, m + 2);
597 
598 	if (jd_flag)
599 		jan1 = firstday(y, 1);
600 
601 	/*
602 	 * Set firstm to the day number of monday of the first week of
603 	 * this month. (This might be in the last month)
604 	 */
605 	firstm = first - weekday(first);
606 
607 	/* Set ds (daystring) and dw (daywidth) according to the jd_flag */
608 	if (jd_flag) {
609 		ds = jdaystr;
610 		dw = 4;
611 	} else {
612 		ds = daystr;
613 		dw = 3;
614 	}
615 
616 	/*
617 	 * Fill the lines with day of month or day of year (julian day)
618 	 * line index: i, each line is one weekday. column index: j, each
619 	 * column is one day number. print column index: k.
620 	 */
621 	for (i = 0; i != 7; i++) {
622 		for (j = firstm + i, k = 0; j < last; j += 7, k += dw)
623 			if (j >= first) {
624 				if (jd_flag)
625 					dt.d = j - jan1 + 1;
626 				else
627 					sdate(j, &dt);
628 				memcpy(mlines->lines[i] + k,
629 				       ds + dt.d * dw, dw);
630 			} else
631 				memcpy(mlines->lines[i] + k, "    ", dw);
632 		mlines->lines[i][k] = '\0';
633 
634 	}
635 
636 	/* fill the weeknumbers */
637 	if (flag_weeks) {
638 		for (j = firstm, k = 0; j < last;  k += dw, j += 7)
639 			if (j <= nswitch)
640 				memset(mlines->weeks + k, ' ', dw);
641 			else
642 				memcpy(mlines->weeks + k,
643 				    ds + week(j, &i)*dw, dw);
644 		mlines->weeks[k] = '\0';
645 	}
646 }
647 
648 void
649 mkmonthb(int y, int m, int jd_flag, struct monthlines *mlines)
650 {
651 
652 	struct tm tm;		/* for strftime printing local names of
653 				 * months */
654 	date    dt;		/* handy date */
655 	int     dw;		/* width of numbers */
656 	int     first;		/* first day of month */
657 	int     firsts;		/* sunday of first week of month */
658 	int     i, j, k;	/* just indices */
659 	int     jan1 = 0;	/* the first day of this year */
660 	int     last;		/* the first day of next month */
661 	char   *ds;		/* pointer to day strings (daystr or
662 				 * jdaystr) */
663 
664 	/* Set ds (daystring) and dw (daywidth) according to the jd_flag */
665 	if (jd_flag) {
666 		ds = jdaystr;
667 		dw = 4;
668 	} else {
669 		ds = daystr;
670 		dw = 3;
671 	}
672 
673 	/* Set name of month centered */
674 	memset(&tm, 0, sizeof(tm));
675 	tm.tm_mon = m;
676 	strftime(mlines->name, sizeof(mlines->name), "%OB", &tm);
677 
678 	/*
679 	 * Set first and last to the day number of the first day of this
680 	 * month and the first day of next month respectively. Set jan1 to
681 	 * the day number of Jan 1st of this year.
682 	 */
683 	dt.y = y;
684 	dt.m = m + 1;
685 	dt.d = 1;
686 	first = sndaysb(&dt);
687 	if (m == 11) {
688 		dt.y = y + 1;
689 		dt.m = 1;
690 		dt.d = 1;
691 	} else {
692 		dt.y = y;
693 		dt.m = m + 2;
694 		dt.d = 1;
695 	}
696 	last = sndaysb(&dt);
697 
698 	if (jd_flag) {
699 		dt.y = y;
700 		dt.m = 1;
701 		dt.d = 1;
702 		jan1 = sndaysb(&dt);
703 	}
704 
705 	/*
706 	 * Set firsts to the day number of sunday of the first week of
707 	 * this month. (This might be in the last month)
708 	 */
709 	firsts = first - (weekday(first)+1) % 7;
710 
711 	/*
712 	 * Fill the lines with day of month or day of year (Julian day)
713 	 * line index: i, each line is one week. column index: j, each
714 	 * column is one day number. print column index: k.
715 	 */
716 	for (i = 0; i != 6; i++) {
717 		for (j = firsts + 7 * i, k = 0; j < last && k != dw * 7;
718 		     j++, k += dw)
719 			if (j >= first) {
720 				if (jd_flag)
721 					dt.d = j - jan1 + 1;
722 				else
723 					sdateb(j, &dt);
724 				memcpy(mlines->lines[i] + k,
725 				       ds + dt.d * dw, dw);
726 			} else
727 				memcpy(mlines->lines[i] + k, "    ", dw);
728 		if (k == 0)
729 			mlines->lines[i][1] = '\0';
730 		else
731 			mlines->lines[i][k] = '\0';
732 	}
733 }
734 
735 /* Put the local names of weekdays into the wds */
736 void
737 mkweekdays(struct weekdays *wds)
738 {
739 	int i;
740 	struct tm tm;
741 
742 	memset(&tm, 0, sizeof(tm));
743 
744 	for (i = 0; i != 7; i++) {
745 		tm.tm_wday = (i+1) % 7;
746 		strftime(wds->names[i], 4, "%a", &tm);
747 		wds->names[i][2] = ' ';
748 	}
749 }
750 
751 /*
752  * Compute the day number of the first
753  * existing date after the first day in month.
754  * (the first day in month and even the month might not exist!)
755  */
756 int
757 firstday(int y, int m)
758 {
759 	date dt;
760 	int nd;
761 
762 	dt.y = y;
763 	dt.m = m;
764 	dt.d = 1;
765 	nd = sndays(&dt);
766 	for (;;) {
767 		sdate(nd, &dt);
768 		if ((dt.m >= m && dt.y == y) || dt.y > y)
769 			return (nd);
770 		else
771 			nd++;
772 	}
773 	/* NEVER REACHED */
774 }
775 
776 /*
777  * Compute the number of days from date, obey the local switch from
778  * Julian to Gregorian if specified by the user.
779  */
780 int
781 sndays(struct date *d)
782 {
783 
784 	if (nswitch != 0)
785 		if (nswitch < ndaysj(d))
786 			return (ndaysg(d));
787 		else
788 			return (ndaysj(d));
789 	else
790 		return ndaysg(d);
791 }
792 
793 /*
794  * Compute the number of days from date, obey the switch from
795  * Julian to Gregorian as used by UK and her colonies.
796  */
797 int
798 sndaysb(struct date *d)
799 {
800 
801 	if (nswitchb < ndaysj(d))
802 		return (ndaysg(d));
803 	else
804 		return (ndaysj(d));
805 }
806 
807 /* Inverse of sndays */
808 struct date *
809 sdate(int nd, struct date *d)
810 {
811 
812 	if (nswitch < nd)
813 		return (gdate(nd, d));
814 	else
815 		return (jdate(nd, d));
816 }
817 
818 /* Inverse of sndaysb */
819 struct date *
820 sdateb(int nd, struct date *d)
821 {
822 
823 	if (nswitchb < nd)
824 		return (gdate(nd, d));
825 	else
826 		return (jdate(nd, d));
827 }
828 
829 /* Center string t in string s of length w by putting enough leading blanks */
830 char *
831 center(char *s, char *t, int w)
832 {
833 	char blanks[80];
834 
835 	memset(blanks, ' ', sizeof(blanks));
836 	sprintf(s, "%.*s%s", (int)(w - strlen(t)) / 2, blanks, t);
837 	return (s);
838 }
839