ncal.c revision 74573
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
28static const char rcsid[] =
29  "$FreeBSD: head/usr.bin/ncal/ncal.c 74573 2001-03-21 14:24:05Z ache $";
30#endif /* not lint */
31
32#include <calendar.h>
33#include <err.h>
34#include <langinfo.h>
35#include <locale.h>
36#include <stdio.h>
37#include <stdlib.h>
38#include <string.h>
39#include <sysexits.h>
40#include <time.h>
41#include <unistd.h>
42
43/* Width of one month with backward compatibility */
44#define MONTH_WIDTH_B_J 27
45#define MONTH_WIDTH_B 20
46
47#define MONTH_WIDTH_J 24
48#define MONTH_WIDTH 18
49
50#define MAX_WIDTH 28
51
52typedef struct date date;
53
54struct monthlines {
55	char name[MAX_WIDTH + 1];
56	char lines[7][MAX_WIDTH + 1];
57	char weeks[MAX_WIDTH + 1];
58};
59
60struct weekdays {
61	char names[7][4];
62};
63
64/* The switches from Julian to Gregorian in some countries */
65static struct djswitch {
66	char *cc;	/* Country code according to ISO 3166 */
67	char *nm;	/* Name of country */
68	date dt;	/* Last day of Julian calendar */
69} switches[] = {
70	{"AL", "Albania",       {1912, 11, 30}},
71	{"AT", "Austria",       {1583, 10,  5}},
72	{"AU", "Australia",     {1752,  9,  2}},
73	{"BE", "Belgium",       {1582, 12, 14}},
74	{"BG", "Bulgaria",      {1916,  3, 18}},
75	{"CA", "Canada",        {1752,  9,  2}},
76	{"CH", "Switzerland",   {1655,  2, 28}},
77	{"CN", "China",         {1911, 12, 18}},
78	{"CZ", "Czech Republic",{1584,  1,  6}},
79	{"DE", "Germany",       {1700,  2, 18}},
80	{"DK", "Denmark",       {1700,  2, 18}},
81	{"ES", "Spain",         {1582, 10,  4}},
82	{"FI", "Finland",       {1753,  2, 17}},
83	{"FR", "France",        {1582, 12,  9}},
84	{"GB", "United Kingdom",{1752,  9,  2}},
85	{"GR", "Greece",        {1924,  3,  9}},
86	{"HU", "Hungary",       {1587, 10, 21}},
87	{"IS", "Iceland",       {1700, 11, 16}},
88	{"IT", "Italy",         {1582, 10,  4}},
89	{"JP", "Japan",         {1918, 12, 18}},
90	{"LI", "Lithuania",     {1918,  2,  1}},
91	{"LN", "Latin",         {9999, 05, 31}},
92	{"LU", "Luxembourg",    {1582, 12, 14}},
93	{"LV", "Latvia",        {1918,  2,  1}},
94	{"NL", "Netherlands",   {1582, 12, 14}},
95	{"NO", "Norway",        {1700,  2, 18}},
96	{"PL", "Poland",        {1582, 10,  4}},
97	{"PT", "Portugal",      {1582, 10,  4}},
98	{"RO", "Romania",       {1919,  3, 31}},
99	{"RU", "Russia",        {1918,  1, 31}},
100	{"SI", "Slovenia",      {1919,  3,  4}},
101	{"SU", "USSR",          {1920,  3,  4}},
102	{"SW", "Sweden",        {1753,  2, 17}},
103	{"TR", "Turkey",        {1926, 12, 18}},
104	{"US", "United States", {1752,  9,  2}},
105	{"YU", "Yugoslavia",    {1919,  3,  4}}
106};
107
108struct 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 */
113char 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 */
119char 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
157int     flag_weeks;		/* user wants number of week */
158int     nswitch;		/* user defined switch date */
159int	nswitchb;		/* switch date for backward compatibility */
160
161char   *center(char *s, char *t, int w);
162void	mkmonth(int year, int month, int jd_flag, struct monthlines * monthl);
163void    mkmonthb(int year, int month, int jd_flag, struct monthlines * monthl);
164void    mkweekdays(struct weekdays * wds);
165void    printcc(void);
166void    printeaster(int year, int julian, int orthodox);
167void    printmonth(int year, int month, int jd_flag);
168void    printmonthb(int year, int month, int jd_flag);
169void    printyear(int year, int jd_flag);
170void    printyearb(int year, int jd_flag);
171int	firstday(int y, int m);
172date   *sdate(int ndays, struct date * d);
173date   *sdateb(int ndays, struct date * d);
174int     sndays(struct date * d);
175int     sndaysb(struct date * d);
176static void usage(void);
177int     weekdayb(int nd);
178
179int
180main(int argc, char *argv[])
181{
182	struct  djswitch *p, *q;	/* to search user defined switch date */
183	date	never = {10000, 1, 1};	/* outside valid range of dates */
184	date	ukswitch = {1752, 9, 2};/* switch date for Great Britain */
185	int     ch;			/* holds the option character */
186	int     m = 0;			/* month */
187	int	y = 0;			/* year */
188	int     flag_backward = 0;	/* user called cal--backward compat. */
189	int     flag_hole_year = 0;	/* user wants the whole year */
190	int	flag_julian_cal = 0;	/* user wants Julian Calendar */
191	int     flag_julian_day = 0;	/* user wants the Julian day
192					 * numbers */
193	int	flag_orthodox = 0;	/* use wants Orthodox easter */
194	int	flag_easter = 0;	/* use wants easter date */
195	char	*cp;			/* character pointer */
196	char    *locale;		/* locale to get country code */
197
198	/*
199	 * Use locale to determine the country code,
200	 * and use the country code to determine the default
201	 * switchdate and date format from the switches table.
202	 */
203	if ((locale = setlocale(LC_TIME, "")) == NULL)
204		warn("setlocale");
205	if (locale == NULL || locale == "C")
206		locale = "_US";
207	q = switches + sizeof(switches) / sizeof(struct djswitch);
208	for (p = switches; p != q; p++)
209		if ((cp = strstr(locale, p->cc)) != NULL && *(cp - 1) == '_')
210			break;
211	if (p == q) {
212		nswitch = ndaysj(&dftswitch->dt);
213	} else {
214		nswitch = ndaysj(&p->dt);
215		dftswitch = p;
216	}
217
218
219	/*
220	 * Get the filename portion of argv[0] and set flag_backward if
221	 * this program is called "cal".
222	 */
223	for (cp = argv[0]; *cp; cp++)
224		;
225	while (cp >= argv[0] && *cp != '/')
226		cp--;
227	if (strcmp("cal", ++cp) == 0)
228		flag_backward = 1;
229
230	/* Set the switch date to United Kingdom if backwards compatible */
231	if (flag_backward)
232		nswitchb = ndaysj(&ukswitch);
233
234	while ((ch = getopt(argc, argv, "Jejops:wy")) != -1)
235		switch (ch) {
236		case 'J':
237			if (flag_backward)
238				usage();
239			nswitch = ndaysj(&never);
240			flag_julian_cal = 1;
241			break;
242		case 'e':
243			if (flag_backward)
244				usage();
245			flag_easter = 1;
246			break;
247		case 'j':
248			flag_julian_day = 1;
249			break;
250		case 'o':
251			if (flag_backward)
252				usage();
253			flag_orthodox = 1;
254			flag_easter = 1;
255			break;
256		case 'p':
257			if (flag_backward)
258				usage();
259			printcc();
260			return (0);
261			break;
262		case 's':
263			if (flag_backward)
264				usage();
265			q = switches +
266			    sizeof(switches) / sizeof(struct djswitch);
267			for (p = switches;
268			     p != q && strcmp(p->cc, optarg) != 0; p++)
269				;
270			if (p == q)
271				errx(EX_USAGE,
272				    "%s: invalid country code", optarg);
273			nswitch = ndaysj(&(p->dt));
274			break;
275		case 'w':
276			if (flag_backward)
277				usage();
278			flag_weeks = 1;
279			break;
280		case 'y':
281			flag_hole_year = 1;
282			break;
283		default:
284			usage();
285		}
286
287	argc -= optind;
288	argv += optind;
289
290	if (argc == 0) {
291		time_t t;
292		struct tm *tm;
293
294		t = time(NULL);
295		tm = localtime(&t);
296		y = tm->tm_year + 1900;
297		m = tm->tm_mon + 1;
298	}
299
300	switch (argc) {
301	case 2:
302		if (flag_easter)
303			usage();
304		m = atoi(*argv++);
305		if (m < 1 || m > 12)
306			errx(EX_USAGE, "month %d not in range 1..12", m);
307		/* FALLTHROUGH */
308	case 1:
309		y = atoi(*argv++);
310		if (y < 1 || y > 9999)
311			errx(EX_USAGE, "year %d not in range 1..9999", y);
312		break;
313	case 0:
314		break;
315	default:
316		usage();
317	}
318
319	if (flag_easter)
320		printeaster(y, flag_julian_cal, flag_orthodox);
321	else if (argc == 1 || flag_hole_year)
322		if (flag_backward)
323			printyearb(y, flag_julian_day);
324		else
325			printyear(y, flag_julian_day);
326	else
327		if (flag_backward)
328			printmonthb(y, m, flag_julian_day);
329		else
330			printmonth(y, m, flag_julian_day);
331
332	return (0);
333}
334
335static void
336usage(void)
337{
338
339	fprintf(stderr, "%s\n%s\n%s\n",
340	    "usage: cal [-jy] [[month] year]",
341	    "       ncal [-Jjpwy] [-s country_code] [[month] year]",
342	    "       ncal [-Jeo] [year]");
343	exit(EX_USAGE);
344}
345
346/* print the assumed switches for all countries */
347void
348printcc(void)
349{
350	struct djswitch *p;
351	int n;	/* number of lines to print */
352	int m;	/* offset from left to right table entry on the same line */
353
354#define FSTR "%c%s %-15s%4d-%02d-%02d"
355#define DFLT(p) ((p) == dftswitch ? '*' : ' ')
356#define FSTRARG(p) DFLT(p), (p)->cc, (p)->nm, (p)->dt.y, (p)->dt.m, (p)->dt.d
357
358	n = sizeof(switches) / sizeof(struct djswitch);
359	m = (n + 1) / 2;
360	n /= 2;
361	for (p = switches; p != switches + n; p++)
362		printf(FSTR"     "FSTR"\n", FSTRARG(p), FSTRARG(p+m));
363	if (m != n)
364		printf(FSTR"\n", FSTRARG(p));
365}
366
367/* print the date of easter sunday */
368void
369printeaster(int y, int julian, int orthodox)
370{
371	date    dt;
372	struct tm tm;
373	char    buf[80];
374	static int d_first = -1;
375
376	if (d_first < 0)
377		d_first = (*nl_langinfo(D_MD_ORDER) == 'd');
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), d_first ? "%e %B %Y" : "%B %e %Y",  &tm);
395	printf("%s\n", buf);
396}
397
398void
399printmonth(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
414void
415printmonthb(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
444void
445printyear(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
501void
502printyearb(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
566void
567mkmonth(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
648void
649mkmonthb(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 */
736void
737mkweekdays(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 */
756int
757firstday(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 */
780int
781sndays(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 */
797int
798sndaysb(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 */
808struct date *
809sdate(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 */
819struct date *
820sdateb(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 */
830char *
831center(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