1 // Copyright 2016 Google Inc. All rights reserved.
2 // Use of this source code is governed by a BSD-style
3 // license that can be found in the LICENSE file.
13 // A Time represents a time as the number of 100's of nanoseconds since 15 Oct
18 lillian = 2299160 // Julian day of 15 Oct 1582
19 unix = 2440587 // Julian day of 1 Jan 1970
20 epoch = unix - lillian // Days between epochs
21 g1582 = epoch * 86400 // seconds between epochs
22 g1582ns100 = g1582 * 10000000 // 100s of a nanoseconds between epochs
27 lasttime uint64 // last time we returned
28 clockSeq uint16 // clock sequence for this run
30 timeNow = time.Now // for testing
33 // UnixTime converts t the number of seconds and nanoseconds using the Unix
34 // epoch of 1 Jan 1970.
35 func (t Time) UnixTime() (sec, nsec int64) {
36 sec = int64(t - g1582ns100)
37 nsec = (sec % 10000000) * 100
42 // GetTime returns the current Time (100s of nanoseconds since 15 Oct 1582) and
43 // clock sequence as well as adjusting the clock sequence as needed. An error
44 // is returned if the current time cannot be determined.
45 func GetTime() (Time, uint16, error) {
51 func getTime() (Time, uint16, error) {
54 // If we don't have a clock sequence already, set one.
58 now := uint64(t.UnixNano()/100) + g1582ns100
60 // If time has gone backwards with this clock sequence then we
61 // increment the clock sequence
63 clockSeq = ((clockSeq + 1) & 0x3fff) | 0x8000
66 return Time(now), clockSeq, nil
69 // ClockSequence returns the current clock sequence, generating one if not
70 // already set. The clock sequence is only used for Version 1 UUIDs.
72 // The uuid package does not use global static storage for the clock sequence or
73 // the last time a UUID was generated. Unless SetClockSequence is used, a new
74 // random clock sequence is generated the first time a clock sequence is
75 // requested by ClockSequence, GetTime, or NewUUID. (section 4.2.1.1)
76 func ClockSequence() int {
79 return clockSequence()
82 func clockSequence() int {
86 return int(clockSeq & 0x3fff)
89 // SetClockSequence sets the clock sequence to the lower 14 bits of seq. Setting to
90 // -1 causes a new sequence to be generated.
91 func SetClockSequence(seq int) {
97 func setClockSequence(seq int) {
100 randomBits(b[:]) // clock sequence
101 seq = int(b[0])<<8 | int(b[1])
104 clockSeq = uint16(seq&0x3fff) | 0x8000 // Set our variant
105 if oldSeq != clockSeq {
110 // Time returns the time in 100s of nanoseconds since 15 Oct 1582 encoded in
111 // uuid. The time is only defined for version 1 and 2 UUIDs.
112 func (uuid UUID) Time() Time {
113 time := int64(binary.BigEndian.Uint32(uuid[0:4]))
114 time |= int64(binary.BigEndian.Uint16(uuid[4:6])) << 32
115 time |= int64(binary.BigEndian.Uint16(uuid[6:8])&0xfff) << 48
119 // ClockSequence returns the clock sequence encoded in uuid.
120 // The clock sequence is only well defined for version 1 and 2 UUIDs.
121 func (uuid UUID) ClockSequence() int {
122 return int(binary.BigEndian.Uint16(uuid[8:10])) & 0x3fff