From: Tom London <tbl@research.uucp>
Date: Wed, 13 Dec 1978 09:20:22 +0000 (-0500)
Subject: Bell 32V development
X-Git-Tag: Bell-32V~414
X-Git-Url: https://git.subgeniuskitty.com/unix-history/.git/commitdiff_plain/60ab3dea3a6be0b639274c6e0cdb2063e84e38b0

Bell 32V development
Work on file usr/src/libc/gen/ctime.c

Co-Authored-By: John Reiser <jfr@research.uucp>
Synthesized-from: 32v
---

diff --git a/usr/src/libc/gen/ctime.c b/usr/src/libc/gen/ctime.c
new file mode 100644
index 0000000000..cd8b9aa5e1
--- /dev/null
+++ b/usr/src/libc/gen/ctime.c
@@ -0,0 +1,245 @@
+/*
+ * This routine converts time as follows.
+ * The epoch is 0000 Jan 1 1970 GMT.
+ * The argument time is in seconds since then.
+ * The localtime(t) entry returns a pointer to an array
+ * containing
+ *  seconds (0-59)
+ *  minutes (0-59)
+ *  hours (0-23)
+ *  day of month (1-31)
+ *  month (0-11)
+ *  year-1970
+ *  weekday (0-6, Sun is 0)
+ *  day of the year
+ *  daylight savings flag
+ *
+ * The routine calls the system to determine the local
+ * timezone and whether Daylight Saving Time is permitted locally.
+ * (DST is then determined by the current US standard rules)
+ * There is a table that accounts for the peculiarities
+ * undergone by daylight time in 1974-1975.
+ *
+ * The routine does not work
+ * in Saudi Arabia which runs on Solar time.
+ *
+ * asctime(tvec))
+ * where tvec is produced by localtime
+ * returns a ptr to a character string
+ * that has the ascii time in the form
+ *	Thu Jan 01 00:00:00 1970n0\\
+ *	01234567890123456789012345
+ *	0	  1	    2
+ *
+ * ctime(t) just calls localtime, then asctime.
+ */
+
+#include <time.h>
+#include <sys/types.h>
+#include <sys/timeb.h>
+
+static	char	cbuf[26];
+static	int	dmsize[12] =
+{
+	31,
+	28,
+	31,
+	30,
+	31,
+	30,
+	31,
+	31,
+	30,
+	31,
+	30,
+	31
+};
+
+/*
+ * The following table is used for 1974 and 1975 and
+ * gives the day number of the first day after the Sunday of the
+ * change.
+ */
+static struct {
+	int	daylb;
+	int	dayle;
+} daytab[] = {
+	5,	333,	/* 1974: Jan 6 - last Sun. in Nov */
+	58,	303,	/* 1975: Last Sun. in Feb - last Sun in Oct */
+};
+
+struct tm	*gmtime();
+char		*ct_numb();
+struct tm	*localtime();
+char	*ctime();
+char	*ct_num();
+char	*asctime();
+
+char *
+ctime(t)
+long *t;
+{
+	return(asctime(localtime(t)));
+}
+
+struct tm *
+localtime(tim)
+long *tim;
+{
+	register int dayno;
+	register struct tm *ct;
+	register daylbegin, daylend;
+	long copyt;
+	struct timeb systime;
+
+	ftime(&systime);
+	copyt = *tim - (long)systime.timezone*60;
+	ct = gmtime(&copyt);
+	dayno = ct->tm_yday;
+	daylbegin = 119;	/* last Sun in Apr */
+	daylend = 303;		/* Last Sun in Oct */
+	if (ct->tm_year==74 || ct->tm_year==75) {
+		daylbegin = daytab[ct->tm_year-74].daylb;
+		daylend = daytab[ct->tm_year-74].dayle;
+	}
+	daylbegin = sunday(ct, daylbegin);
+	daylend = sunday(ct, daylend);
+	if (systime.dstflag &&
+	    (dayno>daylbegin || (dayno==daylbegin && ct->tm_hour>=2)) &&
+	    (dayno<daylend || (dayno==daylend && ct->tm_hour<1))) {
+		copyt += 1*60*60;
+		ct = gmtime(&copyt);
+		ct->tm_isdst++;
+	}
+	return(ct);
+}
+
+/*
+ * The argument is a 0-origin day number.
+ * The value is the day number of the first
+ * Sunday on or after the day.
+ */
+static
+sunday(t, d)
+register struct tm *t;
+register int d;
+{
+	if (d >= 58)
+		d += dysize(t->tm_year) - 365;
+	return(d - (d - t->tm_yday + t->tm_wday + 700) % 7);
+}
+
+struct tm *
+gmtime(tim)
+long *tim;
+{
+	register int d0, d1;
+	long hms, day;
+	register int *tp;
+	static struct tm xtime;
+
+	/*
+	 * break initial number into days
+	 */
+	hms = *tim % 86400;
+	day = *tim / 86400;
+	if (hms<0) {
+		hms += 86400;
+		day -= 1;
+	}
+	tp = (int *)&xtime;
+
+	/*
+	 * generate hours:minutes:seconds
+	 */
+	*tp++ = hms%60;
+	d1 = hms/60;
+	*tp++ = d1%60;
+	d1 /= 60;
+	*tp++ = d1;
+
+	/*
+	 * day is the day number.
+	 * generate day of the week.
+	 * The addend is 4 mod 7 (1/1/1970 was Thursday)
+	 */
+
+	xtime.tm_wday = (day+7340036)%7;
+
+	/*
+	 * year number
+	 */
+	if (day>=0) for(d1=70; day >= dysize(d1); d1++)
+		day -= dysize(d1);
+	else for (d1=70; day<0; d1--)
+		day += dysize(d1-1);
+	xtime.tm_year = d1;
+	xtime.tm_yday = d0 = day;
+
+	/*
+	 * generate month
+	 */
+
+	if (dysize(d1)==366)
+		dmsize[1] = 29;
+	for(d1=0; d0 >= dmsize[d1]; d1++)
+		d0 -= dmsize[d1];
+	dmsize[1] = 28;
+	*tp++ = d0+1;
+	*tp++ = d1;
+	xtime.tm_isdst = 0;
+	return(&xtime);
+}
+
+char *
+asctime(t)
+struct tm *t;
+{
+	register char *cp, *ncp;
+	register int *tp;
+
+	cp = cbuf;
+	for (ncp = "Day Mon 00 00:00:00 1900\n"; *cp++ = *ncp++;);
+	ncp = &"SunMonTueWedThuFriSat"[3*t->tm_wday];
+	cp = cbuf;
+	*cp++ = *ncp++;
+	*cp++ = *ncp++;
+	*cp++ = *ncp++;
+	cp++;
+	tp = &t->tm_mon;
+	ncp = &"JanFebMarAprMayJunJulAugSepOctNovDec"[(*tp)*3];
+	*cp++ = *ncp++;
+	*cp++ = *ncp++;
+	*cp++ = *ncp++;
+	cp = ct_numb(cp, *--tp);
+	cp = ct_numb(cp, *--tp+100);
+	cp = ct_numb(cp, *--tp+100);
+	cp = ct_numb(cp, *--tp+100);
+	if (t->tm_year>=100) {
+		cp[1] = '2';
+		cp[2] = '0';
+	}
+	cp += 2;
+	cp = ct_numb(cp, t->tm_year+100);
+	return(cbuf);
+}
+
+dysize(y)
+{
+	if((y%4) == 0)
+		return(366);
+	return(365);
+}
+
+static char *
+ct_numb(cp, n)
+register char *cp;
+{
+	cp++;
+	if (n>=10)
+		*cp++ = (n/10)%10 + '0';
+	else
+		*cp++ = ' ';
+	*cp++ = n%10 + '0';
+	return(cp);
+}