Function bytesToHeader

js/src/index.ts:489–526

(bytes: ArrayBuffer, etag?: string)

 * Parse raw header bytes into a Header object.
 */
export function bytesToHeader(bytes: ArrayBuffer, etag?: string): Header {
  const v = new DataView(bytes);
  const specVersion = v.getUint8(7);
  if (specVersion > 3) {
    throw new Error(
      `Archive is spec version ${specVersion} but this library supports up to spec version 3`
    );
  }

  return {
    specVersion: specVersion,
    rootDirectoryOffset: getUint64(v, 8),
    rootDirectoryLength: getUint64(v, 16),
    jsonMetadataOffset: getUint64(v, 24),
    jsonMetadataLength: getUint64(v, 32),
    leafDirectoryOffset: getUint64(v, 40),
    leafDirectoryLength: getUint64(v, 48),
    tileDataOffset: getUint64(v, 56),
    tileDataLength: getUint64(v, 64),
    numAddressedTiles: getUint64(v, 72),
    numTileEntries: getUint64(v, 80),
    numTileContents: getUint64(v, 88),
    clustered: v.getUint8(96) === 1,
    internalCompression: v.getUint8(97),
    tileCompression: v.getUint8(98),
    tileType: v.getUint8(99),
    minZoom: v.getUint8(100),
    maxZoom: v.getUint8(101),
    minLon: v.getInt32(102, true) / 10000000,
    minLat: v.getInt32(106, true) / 10000000,
    maxLon: v.getInt32(110, true) / 10000000,
    maxLat: v.getInt32(114, true) / 10000000,
    centerZoom: v.getUint8(118),
    centerLon: v.getInt32(119, true) / 10000000,
    centerLat: v.getInt32(123, true) / 10000000,
    etag: etag,
  };
}

function deserializeIndex(buffer: ArrayBuffer): Entry[] {
  const p = { buf: new Uint8Array(buffer), pos: 0 };