Bug #4966: Alternative optimization for timeDeltaToJulianDelta

src/mtime_timedelta.c

@@ -555,13 +555,11 @@ localTimeDeltaToJulianDelta_StandardTimeDelta_CalTypeGREGORIAN(struct _timedelta
 	      ndiny = NO_OF_DAYS_IN_A_YEAR_FOR_CAL_TYPE365;
 	    }
 
-	  int64_t i = 0L;
-
 	  /* Fast-Fwd >= 400 */
-          for (i = base_dt->date.year; ((base_dt->date.year + td->year - i) >= 400); i = i + 400)
-            {
-                  jd_return->day = jd_return->day + NO_OF_DAYS_IN_400_YEARS;
-            }
+	  int numberOf400YearPeriods = td->year / 400;
+	  int64_t i =  base_dt->date.year + numberOf400YearPeriods * 400;
+	  jd_return->day = jd_return->day + numberOf400YearPeriods * NO_OF_DAYS_IN_400_YEARS;
+
 
 	  /* The year from (target date - 399) to base_date + delta years - 1 */
 	  for (; i < base_dt->date.year + td->year; i++)
@@ -621,13 +619,10 @@ localTimeDeltaToJulianDelta_StandardTimeDelta_CalTypeGREGORIAN(struct _timedelta
 	      ndiny = NO_OF_DAYS_IN_A_YEAR_FOR_CAL_TYPE365;
 	    }
 
-	  int64_t i = 0L;
-
-           /* Fast-Fwd: >= 400 */
-          for (i = base_dt->date.year; (base_dt->date.year - td->year - i <= -400 ); i = i - 400)
-            {
-                  jd_return->day = jd_return->day - NO_OF_DAYS_IN_400_YEARS;
-            }
+	   /* Fast-Fwd: >= 400 */
+	  int numberOf400YearPeriods = td->year / -400;
+	  int64_t i =  base_dt->date.year + numberOf400YearPeriods * -400;
+	  jd_return->day = jd_return->day - numberOf400YearPeriods * NO_OF_DAYS_IN_400_YEARS;
 
 
 	  /* The year from (target date + 399) to base_date - delta years + 1 */
@@ -805,6 +800,16 @@ julianDeltaToTimeDelta(struct _juliandelta* jd, struct _datetime* base_dt, struc
           int64_t j = base_dt->date.year;
           /* Initialize to 0. */
           td_return->year = 0;
+
+		  /* Fast-Fwd: >= 400 */
+          while (days >= NO_OF_DAYS_IN_400_YEARS)
+            {
+                  td_return->year = td_return->year + 400;
+                  j = j + 400;
+                  days = days - NO_OF_DAYS_IN_400_YEARS;
+
+            };
+
           do
             {
 
@@ -895,6 +900,16 @@ julianDeltaToTimeDelta(struct _juliandelta* jd, struct _datetime* base_dt, struc
           int64_t j = base_dt->date.year;
           /* Initialize. */
           td_return->year = 0;
+
+	  /* Fast-Fwd: >= 400  */
+          while (days >= NO_OF_DAYS_IN_400_YEARS)
+            {
+                  td_return->year = td_return->year + 400;
+                  j = j - 400;
+                  days = days - NO_OF_DAYS_IN_400_YEARS;
+		
+            };
+
           do
             {
               /* Loop over and get the year by substracting 366/365 days depending