initial import

1 files changed, 84 insertions, 0 deletions

diff --git a/time/offtime.c b/time/offtime.c
new file mode 100644
index 0000000000..a392a47e89
--- /dev/null
+++ b/time/offtime.c
@@ -0,0 +1,84 @@
+/* Copyright (C) 1991, 1993 Free Software Foundation, Inc.
+This file is part of the GNU C Library.
+
+The GNU C Library is free software; you can redistribute it and/or
+modify it under the terms of the GNU Library General Public License as
+published by the Free Software Foundation; either version 2 of the
+License, or (at your option) any later version.
+
+The GNU C Library is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+Library General Public License for more details.
+
+You should have received a copy of the GNU Library General Public
+License along with the GNU C Library; see the file COPYING.LIB.  If
+not, write to the Free Software Foundation, Inc., 675 Mass Ave,
+Cambridge, MA 02139, USA.  */
+
+#include <ansidecl.h>
+#include <time.h>
+
+
+/* Defined in mktime.c.  */
+extern CONST unsigned short int __mon_lengths[2][12];
+
+#define	SECS_PER_HOUR	(60 * 60)
+#define	SECS_PER_DAY	(SECS_PER_HOUR * 24)
+
+/* Returns the `struct tm' representation of *T,
+   offset OFFSET seconds east of UCT.	*/
+struct tm *
+DEFUN(__offtime, (t, offset), CONST time_t *t AND long int offset)
+{
+  static struct tm tbuf;
+  register long int days, rem;
+  register int y;
+  register CONST unsigned short int *ip;
+
+  if (t == NULL)
+    return NULL;
+
+  days = *t / SECS_PER_DAY;
+  rem = *t % SECS_PER_DAY;
+  rem += offset;
+  while (rem < 0)
+    {
+      rem += SECS_PER_DAY;
+      --days;
+    }
+  while (rem >= SECS_PER_DAY)
+    {
+      rem -= SECS_PER_DAY;
+      ++days;
+    }
+  tbuf.tm_hour = rem / SECS_PER_HOUR;
+  rem %= SECS_PER_HOUR;
+  tbuf.tm_min = rem / 60;
+  tbuf.tm_sec = rem % 60;
+  /* January 1, 1970 was a Thursday.  */
+  tbuf.tm_wday = (4 + days) % 7;
+  if (tbuf.tm_wday < 0)
+    tbuf.tm_wday += 7;
+  y = 1970;
+  while (days >= (rem = __isleap(y) ? 366 : 365))
+    {
+      ++y;
+      days -= rem;
+    }
+  while (days < 0)
+    {
+      --y;
+      days += __isleap(y) ? 366 : 365;
+    }
+  tbuf.tm_year = y - 1900;
+  tbuf.tm_yday = days;
+  ip = __mon_lengths[__isleap(y)];
+  for (y = 0; days >= ip[y]; ++y)
+    days -= ip[y];
+  tbuf.tm_mon = y;
+  tbuf.tm_mday = days + 1;
+  tbuf.tm_isdst = -1;
+
+  return &tbuf;
+}