Function v7Bytes

src/v7.ts:76–133

(
  rnds: Uint8Array,
  msecs?: number,
  seq?: number,
  buf?: Uint8Array,
  offset = 0,
)

}

function v7Bytes(
  rnds: Uint8Array,
  msecs?: number,
  seq?: number,
  buf?: Uint8Array,
  offset = 0,
) {
  if (rnds.length < 16) {
    throw new Error('Random bytes length must be >= 16');
  }

  if (!buf) {
    buf = new Uint8Array(16);
    offset = 0;
  } else {
    if (offset < 0 || offset + 16 > buf.length) {
      throw new RangeError(
        `UUID byte range ${offset}:${offset + 15} is out of buffer bounds`,
      );
    }
  }

  // Defaults
  msecs ??= Date.now();
  seq ??= ((rnds[6] * 0x7f) << 24) | (rnds[7] << 16) | (rnds[8] << 8) | rnds[9];

  // byte 0-5: timestamp (48 bits)
  buf[offset++] = (msecs / 0x10000000000) & 0xff;
  buf[offset++] = (msecs / 0x100000000) & 0xff;
  buf[offset++] = (msecs / 0x1000000) & 0xff;
  buf[offset++] = (msecs / 0x10000) & 0xff;
  buf[offset++] = (msecs / 0x100) & 0xff;
  buf[offset++] = msecs & 0xff;

  // byte 6: `version` (4 bits) | sequence bits 28-31 (4 bits)
  buf[offset++] = 0x70 | ((seq >>> 28) & 0x0f);

  // byte 7: sequence bits 20-27 (8 bits)
  buf[offset++] = (seq >>> 20) & 0xff;

  // byte 8: `variant` (2 bits) | sequence bits 14-19 (6 bits)
  buf[offset++] = 0x80 | ((seq >>> 14) & 0x3f);

  // byte 9: sequence bits 6-13 (8 bits)
  buf[offset++] = (seq >>> 6) & 0xff;

  // byte 10: sequence bits 0-5 (6 bits) | random (2 bits)
  buf[offset++] = ((seq << 2) & 0xff) | (rnds[10] & 0x03);

  // bytes 11-15: random (40 bits)
  buf[offset++] = rnds[11];
  buf[offset++] = rnds[12];
  buf[offset++] = rnds[13];
  buf[offset++] = rnds[14];
  buf[offset++] = rnds[15];

  return buf;
}