Bug 365997: updated PR_USPacificTimeParameters with the new US Daylight

Saving Time rule.  By Nelson Bolyard of Sun Microsystems.  r=wtc.
 Tag: NSPR_4_6_BRANCH

1 files changed, 82 insertions, 48 deletions

diff --git a/pr/src/misc/prtime.c b/pr/src/misc/prtime.c
index 17d13bcd..3736d699 100644
--- a/pr/src/misc/prtime.c
+++ b/pr/src/misc/prtime.c
@@ -789,9 +789,53 @@ PR_LocalTimeParameters(const PRExplodedTime *gmt)
  *------------------------------------------------------------------------
  */
 
+/*
+ * Returns the mday of the first sunday of the month, where
+ * mday and wday are for a given day in the month.
+ * mdays start with 1 (e.g. 1..31).  
+ * wdays start with 0 and are in the range 0..6.  0 = Sunday.
+ */
+#define firstSunday(mday, wday) (((mday - wday + 7 - 1) % 7) + 1)
+
+/*
+ * Returns the mday for the N'th Sunday of the month, where 
+ * mday and wday are for a given day in the month.
+ * mdays start with 1 (e.g. 1..31).  
+ * wdays start with 0 and are in the range 0..6.  0 = Sunday.
+ * N has the following values: 0 = first, 1 = second (etc), -1 = last.
+ * ndays is the number of days in that month, the same value as the 
+ * mday of the last day of the month.
+ */
+static PRInt32 
+NthSunday(PRInt32 mday, PRInt32 wday, PRInt32 N, PRInt32 ndays) 
+{
+    PRInt32 firstSun = firstSunday(mday, wday);
+
+    if (N < 0) 
+        N = (ndays - firstSun) / 7;
+    return firstSun + (7 * N);
+}
+
+typedef struct DSTParams {
+    PRInt8 dst_start_month;       /* 0 = January */
+    PRInt8 dst_start_Nth_Sunday;  /* N as defined above */
+    PRInt8 dst_start_month_ndays; /* ndays as defined above */
+    PRInt8 dst_end_month;         /* 0 = January */
+    PRInt8 dst_end_Nth_Sunday;    /* N as defined above */
+    PRInt8 dst_end_month_ndays;   /* ndays as defined above */
+} DSTParams;
+
+static const DSTParams dstParams[2] = {
+    /* year < 2007:  First April Sunday - Last October Sunday */
+    { 3, 0, 30, 9, -1, 31 },
+    /* year >= 2007: Second March Sunday - First November Sunday */
+    { 2, 1, 31, 10, 0, 30 }
+};
+
 PR_IMPLEMENT(PRTimeParameters)
 PR_USPacificTimeParameters(const PRExplodedTime *gmt)
 {
+    const DSTParams *dst;
     PRTimeParameters retVal;
     PRExplodedTime st;
 
@@ -821,61 +865,51 @@ PR_USPacificTimeParameters(const PRExplodedTime *gmt)
     /* Apply the offset to GMT to obtain the local standard time */
     ApplySecOffset(&st, retVal.tp_gmt_offset);
 
+    if (st.tm_year < 2007) { /* first April Sunday - Last October Sunday */
+	dst = &dstParams[0];
+    } else {                 /* Second March Sunday - First November Sunday */
+	dst = &dstParams[1];
+    }
+
     /*
      * Apply the rules on standard time or GMT to obtain daylight saving
      * time offset.  In this implementation, we use the US DST rule.
      */
-    if (st.tm_month < 3) {
+    if (st.tm_month < dst->dst_start_month) {
         retVal.tp_dst_offset = 0L;
-    } else if (st.tm_month == 3) {
-        if (st.tm_wday == 0) {
-            /* A Sunday */
-            if (st.tm_mday <= 7) {
-                /* First Sunday */
-                /* 01:59:59 PST -> 03:00:00 PDT */
-                if (st.tm_hour < 2) {
-                    retVal.tp_dst_offset = 0L;
-                } else {
-                    retVal.tp_dst_offset = 3600L;
-                }
-            } else {
-                /* Not first Sunday */
-                retVal.tp_dst_offset = 3600L;
-            }
-        } else {
-            /* Not a Sunday.  See if before first Sunday or after */
-            if (st.tm_wday + 1 <= st.tm_mday) {
-                /* After first Sunday */
-                retVal.tp_dst_offset = 3600L;
-            } else {
-                /* Before first Sunday */
-                retVal.tp_dst_offset = 0L;
-            } 
+    } else if (st.tm_month == dst->dst_start_month) {
+	int NthSun = NthSunday(st.tm_mday, st.tm_wday, 
+			       dst->dst_start_Nth_Sunday, 
+			       dst->dst_start_month_ndays);
+	if (st.tm_mday < NthSun) {              /* Before starting Sunday */
+	    retVal.tp_dst_offset = 0L;
+        } else if (st.tm_mday == NthSun) {      /* Starting Sunday */
+	    /* 01:59:59 PST -> 03:00:00 PDT */
+	    if (st.tm_hour < 2) {
+		retVal.tp_dst_offset = 0L;
+	    } else {
+		retVal.tp_dst_offset = 3600L;
+	    }
+	} else {                                /* After starting Sunday */
+	    retVal.tp_dst_offset = 3600L;
         }
-    } else if (st.tm_month < 9) {
+    } else if (st.tm_month < dst->dst_end_month) {
         retVal.tp_dst_offset = 3600L;
-    } else if (st.tm_month == 9) {
-        if (st.tm_wday == 0) {
-            if (31 - st.tm_mday < 7) {
-                /* Last Sunday */
-                /* 01:59:59 PDT -> 01:00:00 PST */
-                if (st.tm_hour < 1) {
-                    retVal.tp_dst_offset = 3600L;
-                } else {
-                    retVal.tp_dst_offset = 0L;
-                }
-            } else {
-                /* Not last Sunday */
-                retVal.tp_dst_offset = 3600L;
-            }
-        } else {
-            /* See if before or after last Sunday */
-            if (7 - st.tm_wday <= 31 - st.tm_mday) {
-                /* before last Sunday */
-                retVal.tp_dst_offset = 3600L;
-            } else {
-                retVal.tp_dst_offset = 0L;
-            }
+    } else if (st.tm_month == dst->dst_end_month) {
+	int NthSun = NthSunday(st.tm_mday, st.tm_wday, 
+			       dst->dst_end_Nth_Sunday, 
+			       dst->dst_end_month_ndays);
+	if (st.tm_mday < NthSun) {              /* Before ending Sunday */
+	    retVal.tp_dst_offset = 3600L;
+        } else if (st.tm_mday == NthSun) {      /* Ending Sunday */
+	    /* 01:59:59 PDT -> 01:00:00 PST */
+	    if (st.tm_hour < 1) {
+		retVal.tp_dst_offset = 3600L;
+	    } else {
+		retVal.tp_dst_offset = 0L;
+	    }
+	} else {                                /* After ending Sunday */
+	    retVal.tp_dst_offset = 0L;
         }
     } else {
         retVal.tp_dst_offset = 0L;