1 var rng = require('./lib/rng');
2 var bytesToUuid = require('./lib/bytesToUuid');
4 // **`v1()` - Generate time-based UUID**
6 // Inspired by https://github.com/LiosK/UUID.js
7 // and http://docs.python.org/library/uuid.html
12 // Previous uuid creation time
16 // See https://github.com/uuidjs/uuid for API details
17 function v1(options, buf, offset) {
18 var i = buf && offset || 0;
21 options = options || {};
22 var node = options.node || _nodeId;
23 var clockseq = options.clockseq !== undefined ? options.clockseq : _clockseq;
25 // node and clockseq need to be initialized to random values if they're not
26 // specified. We do this lazily to minimize issues related to insufficient
27 // system entropy. See #189
28 if (node == null || clockseq == null) {
29 var seedBytes = rng();
31 // Per 4.5, create and 48-bit node id, (47 random bits + multicast bit = 1)
34 seedBytes[1], seedBytes[2], seedBytes[3], seedBytes[4], seedBytes[5]
37 if (clockseq == null) {
38 // Per 4.2.2, randomize (14 bit) clockseq
39 clockseq = _clockseq = (seedBytes[6] << 8 | seedBytes[7]) & 0x3fff;
43 // UUID timestamps are 100 nano-second units since the Gregorian epoch,
44 // (1582-10-15 00:00). JSNumbers aren't precise enough for this, so
45 // time is handled internally as 'msecs' (integer milliseconds) and 'nsecs'
46 // (100-nanoseconds offset from msecs) since unix epoch, 1970-01-01 00:00.
47 var msecs = options.msecs !== undefined ? options.msecs : new Date().getTime();
49 // Per 4.2.1.2, use count of uuid's generated during the current clock
50 // cycle to simulate higher resolution clock
51 var nsecs = options.nsecs !== undefined ? options.nsecs : _lastNSecs + 1;
53 // Time since last uuid creation (in msecs)
54 var dt = (msecs - _lastMSecs) + (nsecs - _lastNSecs)/10000;
56 // Per 4.2.1.2, Bump clockseq on clock regression
57 if (dt < 0 && options.clockseq === undefined) {
58 clockseq = clockseq + 1 & 0x3fff;
61 // Reset nsecs if clock regresses (new clockseq) or we've moved onto a new
63 if ((dt < 0 || msecs > _lastMSecs) && options.nsecs === undefined) {
67 // Per 4.2.1.2 Throw error if too many uuids are requested
69 throw new Error('uuid.v1(): Can\'t create more than 10M uuids/sec');
76 // Per 4.1.4 - Convert from unix epoch to Gregorian epoch
77 msecs += 12219292800000;
80 var tl = ((msecs & 0xfffffff) * 10000 + nsecs) % 0x100000000;
81 b[i++] = tl >>> 24 & 0xff;
82 b[i++] = tl >>> 16 & 0xff;
83 b[i++] = tl >>> 8 & 0xff;
87 var tmh = (msecs / 0x100000000 * 10000) & 0xfffffff;
88 b[i++] = tmh >>> 8 & 0xff;
91 // `time_high_and_version`
92 b[i++] = tmh >>> 24 & 0xf | 0x10; // include version
93 b[i++] = tmh >>> 16 & 0xff;
95 // `clock_seq_hi_and_reserved` (Per 4.2.2 - include variant)
96 b[i++] = clockseq >>> 8 | 0x80;
99 b[i++] = clockseq & 0xff;
102 for (var n = 0; n < 6; ++n) {
106 return buf ? buf : bytesToUuid(b);