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    Length: 6869 (0x1ad5)
    Types: TextFile
    Notes: UNIX file
    Names: »cal.c«

└─⟦f27320a65⟧ Bits:30001972 Commodore 900 hard disk image with partial source code
    └─⟦f4b8d8c84⟧ UNIX Filesystem
        └─⟦this⟧ »cmd/cal.c« 

TextFile

/*
 * Print calendar for specified year (and month).
 * Allows month to be numeric or alphabetic.
 */

#include <stdio.h>
#include <ctype.h>
#include <time.h>

#define	GREGYEAR 1752		/* Year of start of Gregorian calendar */
#define	GREGMON	 SEP		/* Month of above */
#define	GREGDAY	3		/* day of month of changeover */
#define	GREGADJ	11		/* Adjustment of cal. (days) for Gregorian */
	/* The calendar skipped 11 days after
	 * September 3, 1752 in England.
	 * That made the date jump 12 days
	 * forward rather than the usual 1.
	 * The original Gregorian reform was in
	 * 1582, at which time only 10 days were
	 * suppressed.  France and Russia adopted
	 * the Gregorian calendar after 1752.
	 * My calculations, which don't make
	 * complete sense, suggest that the
	 * corrections would be:
	 *	12 days after 1800
	 *	13 days after 1900
	 * and	14 days after 2100
	 * because the Gregorian calendar skips
	 * leap years which fall on century years
	 * unless they are quadracents and not
	 * 4000 AD.
	 */
#define	TMYBIAS	1900		/* bias of year field in struct tm */

char	*mnames[] = {
	"January", "February", "March", "April", "May", "June",
	"July", "August", "September", "October", "November", "December"
};

/*
 * Days per month array (non-leap).
 * January is at dpm[1].
 */
char	dpm[] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};

char	dayhead[] = " Su Mo Tu We Th Fr Sa";

#define	DAYWIDTH	(sizeof dayhead -1)
#define	GAP	5			/* Gap between months */
#define	CENTRE	((3*DAYWIDTH+2*GAP)/2+2) /* Centred 4 digit year pos. */
#define	MPL	3			/* Months per line */
#define	JAN	1
#define	FEB	2
#define	MAR	3
#define	APR	4
#define	MAY	5
#define	JUN	6
#define	JUL	7
#define	AUG	8
#define	SEP	9
#define	OCT	10
#define	NOV	11
#define	DEC	12


char	caldays[MPL][6][7],		/* 3 per line, 6 lines, 7 days */
	outbuf[BUFSIZ];			/* stdout setbuf */
int	baseday;			/* Weekday of current year's Jan. 1 */

main(argc, argv)
register char	*argv[];
{
	int		month;
	unsigned	year;
	struct tm	*now;
	long		intime;
	long		time();

	setbuf(stdout, outbuf);
	intime = time(NULL);
	now = localtime(&intime);
	month = 0;
	year = now->tm_year + TMYBIAS;
	++argv;
	switch (argc) {
	case 1:
		month = now->tm_mon + 1;
		break;
	case 2:
		if (isdigit(**argv))
			year = atoi(*argv);
		else
			month = getmon(*argv);
		break;
	case 3:
		if (!isdigit(*argv[0]))
			month = getmon(*argv++);
		else if (isdigit(*argv[1])) {
			month = atoi(*argv++);
			if (month == 0)
				month = -1;
		} else
			month = getmon(argv[1]);
		year = atoi(*argv);
		break;
	default:
		usage();
	}
	if (month < 0 || month > 12 || year <= 0 || year > 9999)
		usage();
	cal(year, month);
}

/*
 * Produce a calendar for the specifed year and month.
 * (If month is zero, then do whole year.)
 * Setup baseday for fillcal to speed it up a lot.
 */
cal(yr, mon)
{
	register xmon, pos;
	register wday;

	/*
	 * Start at 1 January, 1 which was a Saturday.
	 */
	wday = 6;
	for (pos=1; pos<yr; pos++) {
		if (pos == GREGYEAR)
			wday -= GREGADJ;
		wday = (wday + (isleap(pos) ? 366 : 365)) % 7;
	}
	baseday = wday;
	if (mon != 0)  {
		fillcal(0, mon, yr);
		outcal(mon, 1);
	} else {
		printf("\n%*d\n", CENTRE, yr);
		pos = 0;
		for (xmon = 1; xmon <= 12; xmon++) {
			fillcal(pos, xmon, yr);
			if (++pos >= MPL) {
				outcal(xmon-MPL+1, MPL);
				pos = 0;
			}
		}
	}
}

/*
 * Fill the caldays array element for the particular month
 * and year specified.
 */
fillcal(pos, month, year)
{
	register i, j, day;
	int wday, special, mdays;

	for (i=0; i<6; i++)
		for (j=0; j<7; j++)
			caldays[pos][i][j] = 0;
	wday = baseday;
	dpm[FEB] = isleap(year) ? 29 : 28;
	special = (year==GREGYEAR);
	for (i=1; i<month; i++) {
		if (special && i==GREGMON)
			wday -= GREGADJ;
		wday = (wday + dpm[i]) % 7;
	}
	special = (special && month==GREGMON);
	mdays = dpm[month];
	i = 0;
	j = wday;
	for (day = 1; day <= mdays; day++) {
		caldays[pos][i][j] = day;
		if (special && day==GREGDAY)
			day += GREGADJ;
		if (++j >= 7) {
			j = 0;
			i++;
		}
	}
}

/*
 * Put out `n' months from caldays, starting at month `mon'.
 */
outcal(mon, n)
{
	register i, j, k;
	int left, cent;
	int val;
	char *name;

	mon--;
	lput('\n');
	for (i=1; i<=n; i++) {
		name = mnames[mon++];
		cent = strlen(name);
		left = (DAYWIDTH-cent)/2;
		spaceover(left);
		lputs(name);
		spaceover(DAYWIDTH+GAP-left-cent);
	}
	lput('\n');
	for (i=1; i<=n; i++) {
		lputs(dayhead);
		spaceover(GAP);
	}
	lput('\n');
	for (j=0; j<6; j++) {
		for (i=0; i<n; i++) {
			for (k=0; k<7; k++) {
				lput(' ');
				val = caldays[i][j][k];
				lput(val>=10 ? val/10 + '0' : ' ');
				if (val)
					lput(val%10 + '0');
				else
					lput(' ');
			}
			spaceover(GAP);
		}
		lput('\n');
	}
}

/*
 * Put out calendar characters saving them up until a
 * newline so that trailing blanks can be stripped.
 */

static	char	lline[100];
static	char	*lp = lline;
lput(c)
register c;
{
	register char *cp;

	if (c != '\n')
		*lp++ = c;
	else {
		for (cp = lp; *--cp == ' '; )
			;
		*++cp = '\n';
		*++cp = '\0';
		printf("%s", lp = lline);
	}
}

/*
 * Put out a string using `lput'.
 */
lputs(s)
register char *s;
{
	while (*s != '\0')
		lput(*s++);
}

spaceover(n)
register n;
{
	if (n>0)
		do {
			lput(' ');
		} while (--n);
}

/*
 * Return 1 on leap years; 0 otherwise.
 */
isleap(yr)
register yr;
{
	if (yr<=GREGYEAR)
		return (yr%4 == 0);
	if (yr%4000 == 0)
		return (0);
	if (yr%400==0 || (yr%100!=0 && yr%4==0))
		return (1);
	return (0);
}

/*
 * Return the month (1-12) from `mname' which is
 * roman numeric, the name in ascii of a month, or wrong.
 * Trailing '.' is accepted as are upper case letters.
 */
struct	months {
	char	*m_name;
	int	m_num;
}	months[] = {
	"i",		JAN,	"jan",		JAN,	"january",	JAN,
	"janvier",	JAN,	"ii",		FEB,	"feb",		FEB,
	"february",	FEB,	"fevrier",	FEB,	"iii",		MAR,
	"mar",		MAR,	"march",	MAR,	"mars",		MAR,
	"iv",		APR,	"apr",		APR,	"april",	APR,
	"avril",	APR,	"v",		MAY,	"may",		MAY,
	"mai",		MAY,	"vi",		JUN,	"jun",		JUN,
	"june",		JUN,	"juin",		JUN,	"vii",		JUL,
	"jul",		JUL,	"july",		JUL,	"juillet",	JUL,
	"viii",		AUG,	"iix",		AUG,	"aug",		AUG,
	"august",	AUG,	"aout",		AUG,	"ix",		SEP,
	"sep",		SEP,	"sept",		SEP,	"september",	SEP,
	"septembre",	SEP,	"x",		OCT,	"oct",		OCT,
	"october",	OCT,	"octobre",	OCT,	"xi",		NOV,
	"nov",		NOV,	"november",	NOV,	"novembre",	NOV,
	"xii",		DEC,	"dec",		DEC,	"december",	DEC,
	"decembre",	DEC,	NULL
};

getmon(mname)
char *mname;
{
	register struct months *mp;
	register char *p1, *p2;

	for (p1 = mname; *p1 != '\0'; p1 += 1)
		if (isupper(*p1))
			*p1 = tolower(*p1);
	if (*--p1 == '.')
		*p1 = '\0';
	for (mp = months; mp->m_name != NULL; mp++) {
		p1 = mname;
		p2 = mp->m_name;
		while (*p1 == *p2 && *p1 != '\0' && *p2 != 0)
			p1 += 1, p2 += 1;
		if (*p1 == *p2)
			return (mp->m_num);
	}
	return (-1);
}

usage()
{
	fprintf(stderr, "Usage: cal [month] [year]\n");
	exit(1);
}