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diff --git a/nuttx/lib/time/lib_calendar2utc.c b/nuttx/lib/time/lib_calendar2utc.c
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+++ b/nuttx/lib/time/lib_calendar2utc.c
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+/****************************************************************************
+ * lib/time/lib_calendar2utc.c
+ *
+ *   Copyright (C) 2007, 2009, 2011 Gregory Nutt. All rights reserved.
+ *   Author: Gregory Nutt <spudmonkey@racsa.co.cr>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in
+ *    the documentation and/or other materials provided with the
+ *    distribution.
+ * 3. Neither the name NuttX nor the names of its contributors may be
+ *    used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
+ * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
+ * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
+ * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
+ * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
+ * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
+ * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+
+#include <stdbool.h>
+#include <time.h>
+#include <debug.h>
+
+#include <nuttx/time.h>
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Constant Data
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function:  clock_gregorian2utc, clock_julian2utc
+ *
+ * Description:
+ *    UTC conversion routines.  These conversions are based
+ *    on algorithms from p. 604 of Seidelman, P. K. 1992.
+ *    Explanatory Supplement to the Astronomical Almanac.
+ *    University Science Books, Mill Valley. 
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_GREGORIAN_TIME
+static time_t clock_gregorian2utc(int year, int month, int day)
+{
+  int temp;
+
+  /* temp = (month - 14)/12; */
+
+  temp = (month <= 2 ? -1:0);
+
+  return (1461*(year + 4800 + temp))/4
+    + (367*(month - 2 - 12*temp))/12
+    - (3*((year + 4900 + temp)/100))/4 + day - 32075;
+}
+
+#ifdef CONFIG_JULIAN_TIME
+static time_t clock_julian2utc(int year, int month, int day)
+{
+  return 367*year
+    - (7*(year + 5001 + (month-9)/7))/4
+    + (275*month)/9
+    + day + 1729777;
+}
+#endif /* CONFIG_JULIAN_TIME */
+#endif /* CONFIG_GREGORIAN_TIME */
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Function:  clock_calendar2utc
+ *
+ * Description:
+ *    Calendar/UTC conversion based on algorithms from p. 604
+ *    of Seidelman, P. K. 1992.  Explanatory Supplement to
+ *    the Astronomical Almanac.  University Science Books,
+ *    Mill Valley. 
+ *
+ ****************************************************************************/
+
+#ifdef CONFIG_GREGORIAN_TIME
+time_t clock_calendar2utc(int year, int month, int day)
+{
+  int dyear;
+#ifdef CONFIG_JULIAN_TIME
+  bool isgreg;
+#endif /* CONFIG_JULIAN_TIME */
+
+  /* Correct year & month ranges.  Shift month into range 1-12 */
+
+  dyear = (month-1) / 12;	
+  month -= 12 * dyear;
+  year += dyear;
+
+  if (month < 1)
+    {
+      month += 12;
+      year -= 1;
+    }
+
+#ifdef CONFIG_JULIAN_TIME
+  /* Determine which calendar to use */
+
+  if (year > GREG_YEAR)
+    {
+      isgreg = true;
+    }
+  else if (year < GREG_YEAR)
+    {
+      isgreg = false;
+    }
+  else if (month > GREG_MONTH)
+    {
+      isgreg = true;
+    }
+  else if (month < GREG_MONTH)
+    {
+      isgreg = false;
+    }
+  else
+    {
+      isgreg = (day >= GREG_DAY);
+    }
+
+  /* Calculate and return date */
+
+  if (isgreg)
+    {
+      return clock_gregorian2utc(year, month, day) - JD_OF_EPOCH;
+    }
+  else
+    {
+      return clock_julian2utc (year, month, day) - JD_OF_EPOCH;
+    }
+
+#else /* CONFIG_JULIAN_TIME */
+
+  return clock_gregorian2utc(year, month, day) - JD_OF_EPOCH;
+
+#endif /* CONFIG_JULIAN_TIME */
+}
+#else
+
+/* A highly simplified version that only handles days in the time
+ * since Jan 1, 1970.
+ */
+
+time_t clock_calendar2utc(int year, int month, int day)
+{
+  struct tm t;
+
+  /* mktime can (kind of) do this */
+
+  t.tm_year = year;
+  t.tm_mon  = month;
+  t.tm_mday = day;
+  t.tm_hour = 0;
+  t.tm_min  = 0;
+  t.tm_sec  = 0;
+  return mktime(&t);
+}
+#endif /* CONFIG_GREGORIAN_TIME */
+