hare

commit f10ac698195c0ba1d73dcb6b84ae9c43944f1abb
parent b71c42164e330b7c6f56f737b002db91eef9900f
Author: Byron Torres <b@torresjrjr.com>
Date:   Thu,  3 Feb 2022 23:29:43 +0000

WIP tai/utc leaps handling

Signed-off-by: Byron Torres <b@torresjrjr.com>

Diffstat:
M
time/chrono/leapsec.ha
 | 
9
++++++++-
M
time/chrono/timescale.ha
 | 
43
++++++++++++++++++++++++++++++++++++++++++-

2 files changed, 50 insertions(+), 2 deletions(-)
diff --git a/time/chrono/leapsec.ha b/time/chrono/leapsec.ha
@@ -24,12 +24,18 @@ use strings;
 // timescales. Therefore, we have decided to take an alternative approach.
 
 // The filepath of the leap-seconds.list file
+export def SECS_1900_1970: i64 = 2208988800;
+
+// The filepath of the leap-seconds.list file
 export def UTC_LEAPSECS_FILE: str = "/usr/share/zoneinfo/leap-seconds.list";
 
 // UTC timestamps and their TAI offsets, sourced from leap-seconds.list
 let utc_leapsecs: [](i64, i64) = [];
 
-// TODO: BUG: Cannot compile harec2 with this line.
+// TODO: Fix, cannot compile harec2 with this line. This code is currenlty
+// called where it's needed, as a workaround. Remember to prune this function
+// call elsewhere once this @init is fixed.
+//
 //@init fn init_utc_leapsecs() void = init_utc_leapsecs();
 
 fn init_utc_leapsecs() void = {
@@ -57,6 +63,7 @@ fn read_leapsecfile(h: io::handle, leapsecs: *[](i64, i64)) (void | io::error) =
 		};
 		const a = strconv::stoi64(pair[0])!;
 		const b = strconv::stoi64(pair[1])!;
+		const a = a - SECS_1900_1970;
 		const pair = (a: i64, b: i64);
 		append(utc_leapsecs, pair);
 	};
diff --git a/time/chrono/timescale.ha b/time/chrono/timescale.ha
@@ -46,6 +46,15 @@ export const utc: timescale = timescale {
 };
 
 fn conv_tai_utc(a: time::instant) (time::instant | time::error) = {
+	init_utc_leapsecs();
+
+	const idx = lookup_leaps(utc_leapsecs, time::unix(a));
+	const ofst = utc_leapsecs[idx].1;
+
+	if (time::unix(a) == utc_leapsecs[idx].0) {
+		void;
+	};
+
 	const b = time::instant {
 		sec = a.sec - 37,
 		nsec = a.nsec,
@@ -54,13 +63,45 @@ fn conv_tai_utc(a: time::instant) (time::instant | time::error) = {
 };
 
 fn conv_utc_tai(a: time::instant) (time::instant | time::error) = {
+	init_utc_leapsecs();
+
+	const idx = lookup_leaps(utc_leapsecs, time::unix(a));
+	const ofst = utc_leapsecs[idx].1;
+
+	if (time::unix(a) == utc_leapsecs[idx].0) {
+		void;
+	};
+
 	const b = time::instant {
-		sec = a.sec + 37,
+		sec = a.sec + ofst,
 		nsec = a.nsec,
 	};
 	return b;
 };
 
+fn lookup_leaps(list: [](i64, i64), t: i64) size = {
+	let lo = 0z, hi = len(list);
+	for (hi - lo > 1) {
+		const mid = lo + (hi - lo) / 2;
+		const middle = list[mid].0;
+		const cmp = time::compare(
+			time::from_unix(t),
+			time::from_unix(middle),
+		);
+		switch (cmp) {
+		case -1 =>
+			hi = mid;
+		case 0 =>
+			lo = mid; break;
+		case 1 =>
+			lo = mid;
+		case =>
+			abort("Unreachable");
+		};
+	};
+	return lo;
+};
+
 
 // Global Positioning System Time
 //