From 4aa3fe62a67788000896fc2b7f17f1078192bbe7 Mon Sep 17 00:00:00 2001
From: Sergey Matveev <stargrave@stargrave.org>
Date: Thu, 10 Dec 2020 16:42:45 +0300
Subject: [PATCH] Initial commit

---
 go.mod    |  3 +++
 tai64n.go | 63 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 66 insertions(+)
 create mode 100644 go.mod
 create mode 100644 tai64n.go

diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..79a8308
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module go.cypherpunks.ru/tai64n
+
+go 1.14
diff --git a/tai64n.go b/tai64n.go
new file mode 100644
index 0000000..34a63d1
--- /dev/null
+++ b/tai64n.go
@@ -0,0 +1,63 @@
+/*
+go.cypherpunks.ru/tai64n -- Pure Go TAI64N implementation
+Copyright (C) 2020 Sergey Matveev <stargrave@stargrave.org>
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, version 3 of the License.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package tai64n
+
+import (
+	"encoding/binary"
+	"encoding/hex"
+	"errors"
+	"strings"
+	"time"
+)
+
+const (
+	Size     = 12
+	Base     = 0x400000000000000a
+	LocalFmt = "2006-01-02 15:04:05.000000000"
+)
+
+type TAI64N [Size]byte
+
+func FromTime(t time.Time, tai *TAI64N) {
+	binary.BigEndian.PutUint64(tai[:], uint64(Base)+uint64(t.Unix()))
+	binary.BigEndian.PutUint32(tai[8:], uint32(t.Nanosecond()))
+}
+
+func ToTime(tai []byte) time.Time {
+	if len(tai) != Size {
+		panic("invalid size")
+	}
+	secs := int64(binary.BigEndian.Uint64(tai[:8]))
+	nano := int64(binary.BigEndian.Uint32(tai[8:]))
+	return time.Unix(secs-Base, nano)
+}
+
+func (tai TAI64N) Encode() string {
+	return "@" + hex.EncodeToString(tai[:])
+}
+
+func Decode(s string) (time.Time, error) {
+	tai, err := hex.DecodeString(strings.TrimPrefix(s, "@"))
+	if len(tai) != Size {
+		return time.Time{}, errors.New("invalid ts length")
+	}
+	if err != nil {
+		return time.Time{}, err
+	}
+	return ToTime(tai), nil
+}
-- 
2.44.0