FEAT: support to date! integer! and to integer! date! using unixtime as an integer value

resolves: Oldes/Rebol-issues#2456

Author: Oldes

src/core/t-date.c

@@ -32,6 +32,8 @@
 
 #include "sys-core.h"
 
+static const REBI64 DAYS_OF_JAN_1ST_1970 = 719468; // number of days for 1st January 1970
+
 
 /***********************************************************************
 **
@@ -309,6 +311,36 @@
 }
 
 
+/***********************************************************************
+**
+*/	REBCNT Date_To_Timestamp(REBVAL *date)
+/*
+**		Return the unix time stamp for a specific date value.
+**
+***********************************************************************/
+{
+	REBDAT d = VAL_DATE(date);
+	REBI64 epoch = (Days_Of_Date(d.date.day, d.date.month, d.date.year) - DAYS_OF_JAN_1ST_1970) * SECS_IN_DAY;
+	return epoch + ((VAL_TIME(date) + 500000000) / SEC_SEC);
+}
+
+/***********************************************************************
+**
+*/	void Timestamp_To_Date(REBVAL *date, REBI64 epoch)
+/*
+**		Set Rebol date from the unix time stamp epoch.
+**
+***********************************************************************/
+{
+	REBI64 days = (epoch / SECS_IN_DAY) + DAYS_OF_JAN_1ST_1970;
+
+	VAL_SET(date, REB_DATE);
+	Date_Of_Days(days, &VAL_DATE(date));
+	VAL_TIME(date) = TIME_SEC((epoch % 86400));
+	VAL_ZONE(date) = 0;
+}
+
+
 /***********************************************************************
 **
 */	void Normalize_Time(REBI64 *sp, REBINT *dp)
@@ -883,6 +915,10 @@
 					return R_RET;
 				}
 			}
+			else if (IS_INTEGER(arg)) {
+				Timestamp_To_Date(D_RET, VAL_INT64(arg));
+				return R_RET;
+			}
 //			else if (IS_NONE(arg)) {
 //				secs = nsec = day = month = year = tz = 0;
 //				goto fixTime; 

src/core/t-integer.c

@@ -245,6 +245,7 @@
 		else if (IS_CHAR(val))
 			num = VAL_CHAR(val);
 		// else if (IS_NONE(val)) num = 0;
+		else if (IS_DATE(val)) num = Date_To_Timestamp(val);
 		else if (IS_TIME (val)) num = SECS_IN(VAL_TIME(val));
 		else goto is_bad;
 		break;

src/mezz/codec-unixtime.reb

@@ -26,12 +26,7 @@ register-codec [
 	][
 		if string? epoch [ epoch: debase epoch 16 ]
 		if binary? epoch [ epoch: to integer! epoch ]
-		days: to integer! tmp: epoch / 86400
-		hours: to integer! time: (tmp - days) * 24
-		minutes: to integer! tmp: (time - hours) * 60
-		seconds: to integer! 0.5 + ((tmp - minutes) * 60)
-		time: to time! ((((hours * 60) + minutes) * 60) + seconds)
-		result: 1-Jan-1970 + days + time
+		result: to date! epoch
 		unless utc [
 			result: result + now/zone
 			result/zone: now/zone
@@ -44,12 +39,7 @@ register-codec [
 		date [date!]
 		/as type [word! datatype!] {one of: [string! binary! integer!]}
 	][
-		time: any [date/time 0:0:0]
-		unix: ((date - 1-1-1970) * 86400)
-			+ (time/hour * 3600)
-			+ (time/minute * 60)
-			+  time/second
-			- to integer! (any [date/zone 0])
+		unix: to integer! date
 		if as [
 			type: to word! type
 			binary/write bin: #{} [ui32 :unix]