From 64bc6412188b141c010ac3b8e813b837dd991e80 Mon Sep 17 00:00:00 2001
From: Erik Andersen <andersen@codepoet.org>
Date: Sun, 14 May 2000 04:16:35 +0000
Subject: Initial revision

---
 libc/misc/time/tm_conv.c | 138 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 138 insertions(+)
 create mode 100644 libc/misc/time/tm_conv.c

(limited to 'libc/misc/time/tm_conv.c')

diff --git a/libc/misc/time/tm_conv.c b/libc/misc/time/tm_conv.c
new file mode 100644
index 000000000..ffd524c4b
--- /dev/null
+++ b/libc/misc/time/tm_conv.c
@@ -0,0 +1,138 @@
+
+#if 0
+#include <time.h>
+
+/* This is a translation from ALGOL in Collected Algorithms of CACM. */
+/* Copied from Algorithm 199, Author: Robert G. Tantzen */
+
+void
+__tm_conv(tmbuf, timep, offset)
+struct tm *tmbuf;
+time_t *timep;
+time_t offset;
+{
+static int   moffset[] =
+   {0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334};
+
+   long s;
+   long  j, d, m, y;
+
+   offset += *timep;
+
+   tmbuf->tm_isdst = 0;		/* Someone else can set this */
+
+   j = offset / 86400L + 719469;
+   s = offset % 86400L;
+
+   if( s < 0 ) { s += 86400L; j--; }
+
+   tmbuf->tm_sec = s % 60;
+   tmbuf->tm_min = (s / 60) % 60;
+   tmbuf->tm_hour = s / 3600;
+
+   tmbuf->tm_wday = (j+2) % 7;
+
+   /*
+    * Julian date converter. Takes a julian date (the number of days since
+    * some distant epoch or other), and fills tmbuf.
+    */
+
+   y = (4L * j - 1L) / 146097L;
+   j = 4L * j - 1L - 146097L * y;
+   d = j / 4L;
+   j = (4L * d + 3L) / 1461L;
+   d = 4L * d + 3L - 1461L * j;
+   d = (d + 4L) / 4L;
+   m = (5L * d - 3L) / 153L;
+   d = 5L * d - 3 - 153L * m;
+   d = (d + 5L) / 5L;
+   y = 100L * y + j;
+   if (m < 10)
+      m += 2;
+   else
+   {
+      m -= 10;
+      ++y;
+   }
+
+   tmbuf->tm_year = y - 1900;
+   tmbuf->tm_mon = m;
+   tmbuf->tm_mday = d;
+
+   tmbuf->tm_yday = d + moffset[m];
+   if (m > 1 && ((y) % 4 == 0 && ((y) % 100 != 0 || (y) % 400 == 0)))
+      tmbuf->tm_yday++;
+}
+
+#else
+
+/* This is adapted from glibc */
+/* Copyright (C) 1991, 1993 Free Software Foundation, Inc */
+
+#define SECS_PER_HOUR 3600L
+#define SECS_PER_DAY  86400L
+
+#include <time.h>
+
+static const unsigned short int __mon_lengths[2][12] =
+  {
+    /* Normal years.  */
+    { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 },
+    /* Leap years.  */
+    { 31, 29, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
+  };
+
+
+void
+__tm_conv(tmbuf, t, offset)
+struct tm *tmbuf;
+time_t *t;
+time_t offset;
+{
+  long days, rem;
+  register int y;
+  register unsigned short int *ip;
+
+  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;
+    }
+  tmbuf->tm_hour = rem / SECS_PER_HOUR;
+  rem %= SECS_PER_HOUR;
+  tmbuf->tm_min = rem / 60;
+  tmbuf->tm_sec = rem % 60;
+  /* January 1, 1970 was a Thursday.  */
+  tmbuf->tm_wday = (4 + days) % 7;
+  if (tmbuf->tm_wday < 0)
+    tmbuf->tm_wday += 7;
+  y = 1970;
+  while (days >= (rem = __isleap(y) ? 366 : 365))
+    {
+      ++y;
+      days -= rem;
+    }
+  while (days < 0)
+    {
+      --y;
+      days += __isleap(y) ? 366 : 365;
+    }
+  tmbuf->tm_year = y - 1900;
+  tmbuf->tm_yday = days;
+  ip = __mon_lengths[__isleap(y)];
+  for (y = 0; days >= ip[y]; ++y)
+    days -= ip[y];
+  tmbuf->tm_mon = y;
+  tmbuf->tm_mday = days + 1;
+  tmbuf->tm_isdst = -1;
+}
+
+#endif
-- 
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