X-Git-Url: http://www.git.cypherpunks.ru/?a=blobdiff_plain;f=tai64n.go;h=d3071a37f461625757e450d7be76c737a52fc227;hb=f1c943309e457d9bf9617677584a2f8db828e025;hp=5087361dbbd178975ac962788101893f2b65e650;hpb=dd683a282f1b02438967936e85a8601f90f29400;p=gotai64n.git

diff --git a/tai64n.go b/tai64n.go
index 5087361..d3071a3 100644
--- a/tai64n.go
+++ b/tai64n.go
@@ -1,6 +1,6 @@
 /*
-go.cypherpunks.ru/tai64n -- Pure Go TAI64N implementation
-Copyright (C) 2020 Sergey Matveev <stargrave@stargrave.org>
+go.cypherpunks.ru/tai64n -- Pure Go TAI64/TAI64N implementation
+Copyright (C) 2020-2022 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
@@ -15,6 +15,18 @@ You should have received a copy of the GNU General Public License
 along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
 
+// TAI64/TAI64N (http://cr.yp.to/libtai/tai64.html) dealing library.
+// You can convert time to TAI64/TAI64N and vice versa with it.
+//
+//     tai := new(tai64n.TAI64N)
+//     tai.FromTime(time.Now())
+//     printable := tai64n.Encode(tai[:])
+//     decoded, err := tai64n.Decode(printable)
+//     tai64n.ToTime(tai[:]) == decoded
+//
+// By default TAI64 timestamps contain initial 1972-01-01 10-seconds
+// TAI<->UTC difference. If you need honest TAI representation, then you
+// should also use Leapsecs* functions.
 package tai64n
 
 import (
@@ -26,38 +38,57 @@ import (
 )
 
 const (
-	Size     = 12
-	Base     = 0x400000000000000a
-	LocalFmt = "2006-01-02 15:04:05.000000000"
+	TAI64Size  = 8
+	TAI64NSize = TAI64Size + 4
+	LocalFmt   = "2006-01-02 15:04:05.000000000"
+	Base       = 0x4000000000000000 + Leapsecs1972
 )
 
-type TAI64N [Size]byte
+type TAI64 [TAI64Size]byte
+type TAI64N [TAI64NSize]byte
 
-func FromTime(src time.Time, dst *TAI64N) {
+func (dst *TAI64) FromTime(src time.Time) {
+	binary.BigEndian.PutUint64(dst[:], uint64(Base)+uint64(src.Unix()))
+}
+
+func (dst *TAI64N) FromTime(src time.Time) {
 	binary.BigEndian.PutUint64(dst[:], uint64(Base)+uint64(src.Unix()))
 	binary.BigEndian.PutUint32(dst[8:], uint32(src.Nanosecond()))
 }
 
 func ToTime(tai []byte) time.Time {
-	if len(tai) != Size {
-		panic("invalid size")
+	var secs, nano int64
+	switch len(tai) {
+	case TAI64NSize:
+		nano = int64(binary.BigEndian.Uint32(tai[8:]))
+		fallthrough
+	case TAI64Size:
+		secs = int64(binary.BigEndian.Uint64(tai[:8])) - Base
+	default:
+		panic("invalid tai size")
+	}
+	if secs < 0 {
+		panic("dates < 1970-01-01 are not supported")
 	}
-	secs := int64(binary.BigEndian.Uint64(tai[:8]))
-	nano := int64(binary.BigEndian.Uint32(tai[8:]))
-	return time.Unix(secs-Base, nano)
+	return time.Unix(secs, nano)
 }
 
-func (tai TAI64N) Encode() string {
-	return "@" + hex.EncodeToString(tai[:])
+// Convert TAI64/TAI64N to "@HEX(TAI64)" format.
+func Encode(tai []byte) string {
+	raw := make([]byte, 1+hex.EncodedLen(len(tai)))
+	raw[0] = byte('@')
+	hex.Encode(raw[1:], tai)
+	return string(raw)
 }
 
+// Convert TAI64/TAI64N "@HEX(TAI64)" format to Time.
 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")
+	raw, err := hex.DecodeString(strings.TrimPrefix(s, "@"))
+	if !(len(raw) == TAI64Size || len(raw) == TAI64NSize) {
+		err = errors.New("invalid length")
 	}
-	if err != nil {
-		return time.Time{}, err
+	if err == nil {
+		return ToTime(raw), nil
 	}
-	return ToTime(tai), nil
+	return time.Time{}, err
 }