1 files changed, 95 insertions, 2 deletions
diff --git a/newlib/libc/time/gmtime_r.c b/newlib/libc/time/gmtime_r.c
index 14c9c7640..1111cbc0e 100644
--- a/newlib/libc/time/gmtime_r.c
+++ b/newlib/libc/time/gmtime_r.c
@@ -1,14 +1,107 @@
 /*
  * gmtime_r.c
+ * Original Author: Adapted from tzcode maintained by Arthur David Olson.
+ * Modifications:
+ * - Changed to mktm_r and added __tzcalc_limits - 04/10/02, Jeff Johnston
+ * - Fixed bug in mday computations - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru>
+ * - Fixed bug in __tzcalc_limits - 08/12/04, Alex Mogilnikov <alx@intellectronika.ru>
+ * - Move code from _mktm_r() to gmtime_r() - 05/09/14, Freddie Chopin <freddie_chopin@op.pl>
+ *
+ * Converts the calendar time pointed to by tim_p into a broken-down time
+ * expressed as local time. Returns a pointer to a structure containing the
+ * broken-down time.
  */
 
-#include <time.h>
 #include "local.h"
 
+/* there are 97 leap years in 400-year periods */
+#define DAYS_PER_400_YEARS	((400 - 97) * 365 + 97 * 366)
+/* there are 24 leap years in 100-year periods */
+#define DAYS_PER_100_YEARS	((100 - 24) * 365 + 24 * 366)
+/* there is one leap year every 4 years */
+#define DAYS_PER_4_YEARS	(3 * 365 + 366)
+
+static _CONST int days_per_year[4] = {
+  365,  /* 1970 or 1966 */
+  365,  /* 1971 or 1967 */
+  366,  /* 1972 or 1968 */
+  365   /* 1973 or 1969 */
+} ;
+
 struct tm *
 _DEFUN (gmtime_r, (tim_p, res),
 	_CONST time_t *__restrict tim_p _AND
 	struct tm *__restrict res)
 {
-  return (_mktm_r (tim_p, res, 1));
+  long days, rem;
+  _CONST time_t lcltime = *tim_p;
+  int year;
+  int years400, years100, years4;
+  int yearleap;
+  _CONST int *ip;
+
+  days = ((long)lcltime) / SECSPERDAY;
+  rem = ((long)lcltime) % SECSPERDAY;
+  while (rem < 0)
+    {
+      rem += SECSPERDAY;
+      --days;
+    }
+  while (rem >= SECSPERDAY)
+    {
+      rem -= SECSPERDAY;
+      ++days;
+    }
+
+  /* compute hour, min, and sec */
+  res->tm_hour = (int) (rem / SECSPERHOUR);
+  rem %= SECSPERHOUR;
+  res->tm_min = (int) (rem / SECSPERMIN);
+  res->tm_sec = (int) (rem % SECSPERMIN);
+
+  /* compute day of week */
+  if ((res->tm_wday = ((EPOCH_WDAY + days) % DAYSPERWEEK)) < 0)
+    res->tm_wday += DAYSPERWEEK;
+
+  /* compute year & day of year */
+  years400 = days / DAYS_PER_400_YEARS;
+  days -= years400 * DAYS_PER_400_YEARS;
+  years100 = days / DAYS_PER_100_YEARS;
+  days -= years100 * DAYS_PER_100_YEARS;
+  years4 = days / DAYS_PER_4_YEARS;
+  days -= years4 * DAYS_PER_4_YEARS;
+
+  year = EPOCH_YEAR + years400 * 400 + years100 * 100 + years4 * 4;
+
+  /* the value left in days is based in 1970 */
+  if (days < 0)
+    {
+      ip = &days_per_year[3];
+      while (days < 0)
+        {
+          days += *ip--;
+          --year;
+        }
+    }
+  else
+    {
+      ip = &days_per_year[0];
+      while (days >= *ip)
+        {
+          days -= *ip++;
+          ++year;
+        }
+    }
+
+  res->tm_year = year - YEAR_BASE;
+  res->tm_yday = days;
+  yearleap = isleap(year);
+  ip = __month_lengths[yearleap];
+  for (res->tm_mon = 0; days >= ip[res->tm_mon]; ++res->tm_mon)
+    days -= ip[res->tm_mon];
+  res->tm_mday = days + 1;
+
+  res->tm_isdst = 0;
+
+  return (res);
 }