GPT-5 generated

Author: tshemsedinov

Timestamp48/TASK.md

@@ -0,0 +1,4 @@
+# Timestamp 48 bit
+
+- Implement 48 bit timestamp generator like in UUIDv7 standard
+- Encode generated id in Base64URL format

Timestamp48/gpt-5.js

@@ -0,0 +1,74 @@
+'use strict';
+
+const crypto = require('crypto');
+
+const _state = {
+ lastMs: 0n,
+ seq12: 0,
+};
+
+const _nowMs = () => BigInt(Date.now());
+const _waitNextMs = (currentMs) => {
+ let t = _nowMs();
+ while (t <= currentMs) t = _nowMs();
+ return t;
+};
+
+const _packUuidV7 = (ts48, seq12, randTail8) => {
+ const buf = Buffer.allocUnsafe(16);
+
+ // 48-bit timestamp (big-endian)
+ buf[0] = Number((ts48 >> 40n) & 0xffn);
+ buf[1] = Number((ts48 >> 32n) & 0xffn);
+ buf[2] = Number((ts48 >> 24n) & 0xffn);
+ buf[3] = Number((ts48 >> 16n) & 0xffn);
+ buf[4] = Number((ts48 >> 8n) & 0xffn);
+ buf[5] = Number(ts48 & 0xffn);
+
+ // version (7) and high 4 bits of seq12
+ buf[6] = 0x70 | ((seq12 >> 8) & 0x0f);
+
+ // low 8 bits of seq12
+ buf[7] = seq12 & 0xff;
+
+ // 62 random bits with RFC 4122 variant (10xxxxxx)
+ randTail8[0] = (randTail8[0] & 0x3f) | 0x80;
+ randTail8.copy(buf, 8);
+
+ return buf;
+};
+
+const _toBase64Url = (buf) =>
+ buf
+ .toString('base64')
+ .replace(/\+/g, '-')
+ .replace(/\//g, '_')
+ .replace(/=+$/, '');
+
+/**
+ * Generates a UUIDv7-like 128-bit ID:
+ * - 48-bit Unix ms timestamp
+ * - version 7 nibble
+ * - 12-bit monotonic sequence (per ms)
+ * - variant (RFC 4122)
+ * - 62 random tail bits
+ * Encoded as Base64URL (22 chars).
+ */
+const generateV7Base64Url = () => {
+ let ts = _nowMs();
+ if (ts === _state.lastMs) {
+ _state.seq12 = (_state.seq12 + 1) & 0x0fff;
+ if (_state.seq12 === 0) ts = _waitNextMs(ts);
+ } else {
+ _state.seq12 = crypto.randomInt(0, 0x1000);
+ }
+ _state.lastMs = ts;
+
+ const tail = crypto.randomBytes(8);
+ const bytes = _packUuidV7(ts, _state.seq12, tail);
+ return _toBase64Url(bytes);
+};
+
+module.exports = {
+ generateV7Base64Url,
+};

Timestamp48/gpt-5.mjs

@@ -0,0 +1,81 @@
+// uuidv7-web.mjs (ESM, browser-safe, arrow-only, monotonic, Base64URL)
+
+// internal state (per module instance)
+const _state = {
+ lastMs: 0n,
+ seq12: 0,
+};
+
+const _nowMs = () => BigInt(Date.now());
+const _random12 = () =>
+ globalThis.crypto.getRandomValues(new Uint16Array(1))[0] & 0x0fff;
+const _randomTail8 = () => {
+ const a = new Uint8Array(8);
+ globalThis.crypto.getRandomValues(a);
+ return a;
+};
+
+const _packUuidV7 = (ts48, seq12, randTail8) => {
+ const bytes = new Uint8Array(16);
+
+ // 48-bit timestamp (big-endian)
+ bytes[0] = Number((ts48 >> 40n) & 0xffn);
+ bytes[1] = Number((ts48 >> 32n) & 0xffn);
+ bytes[2] = Number((ts48 >> 24n) & 0xffn);
+ bytes[3] = Number((ts48 >> 16n) & 0xffn);
+ bytes[4] = Number((ts48 >> 8n) & 0xffn);
+ bytes[5] = Number(ts48 & 0xffn);
+
+ // version (7) and high 4 bits of seq12
+ bytes[6] = 0x70 | ((seq12 >> 8) & 0x0f);
+
+ // low 8 bits of seq12
+ bytes[7] = seq12 & 0xff;
+
+ // RFC 4122 variant on next 8 bytes (10xxxxxx)
+ const tail = randTail8.slice(0);
+ tail[0] = (tail[0] & 0x3f) | 0x80;
+ bytes.set(tail, 8);
+
+ return bytes;
+};
+
+const _toBase64Url = (bytes) => {
+ let bin = '';
+ for (let i = 0; i < bytes.length; i += 1) {
+ bin += String.fromCharCode(bytes[i]);
+ }
+ return btoa(bin).replace(/\+/g, '-').replace(/\//g, '_').replace(/=+$/, '');
+};
+
+/**
+ * Generates a UUIDv7-like 128-bit ID:
+ * - 48-bit Unix ms timestamp
+ * - version 7 nibble
+ * - 12-bit monotonic sequence (per ms)
+ * - RFC 4122 variant
+ * - 62 random tail bits
+ * Encoded as Base64URL (22 chars).
+ *
+ * Monotonic strategy (non-blocking):
+ * on seq overflow within same ms, bump the virtual timestamp by +1 ms.
+ */
+export const generateV7Base64Url = () => {
+ const now = _nowMs();
+ let ts = now > _state.lastMs ? now : _state.lastMs;
+
+ if (ts === _state.lastMs) {
+ _state.seq12 = (_state.seq12 + 1) & 0x0fff;
+ if (_state.seq12 === 0) ts = _state.lastMs + 1n; // avoid busy-wait
+ } else {
+ _state.seq12 = _random12();
+ }
+
+ _state.lastMs = ts;
+
+ const tail = _randomTail8();
+ const bytes = _packUuidV7(ts, _state.seq12, tail);
+ return _toBase64Url(bytes);
+};
+
+export default generateV7Base64Url;