Function writePackHeader

src/packFileSerializer.ts:3532–3586

(
  outFile: BinaryFile,
  originalHeader: PackHeader,
  packedFiles: PackedFile[],
  dependencyPacks: string[],
)

  }
};
const writePackHeader = async (
  outFile: BinaryFile,
  originalHeader: PackHeader,
  packedFiles: PackedFile[],
  dependencyPacks: string[],
): Promise<void> => {
  // Write base header
  await outFile.write(originalHeader.header);
  await outFile.writeInt32(originalHeader.byteMask);
  await outFile.writeInt32(originalHeader.refFileCount);
  // Calculate pack index size
  const pack_file_index_size = dependencyPacks.reduce(
    (acc, dep) => acc + Buffer.byteLength(dep, "utf8") + 1,
    0,
  );
  await outFile.writeInt32(pack_file_index_size);
  await outFile.writeInt32(packedFiles.length);
  // Calculate packed file index size
  const packed_file_index_size = packedFiles.reduce(
    (acc, file) => acc + 4 + 1 + Buffer.byteLength(file.name, "utf8") + 1,
    0,
  );
  await outFile.writeInt32(packed_file_index_size);
  await outFile.writeInt32(0x7fffffff); // header_buffer
  // Write dependency packs
  for (const dep of dependencyPacks) {
    await outFile.writeString(dep);
    await outFile.writeUInt8(0);
  }
  // Write file index
  // Pre-calculate total size for file index to write in one batch
  let totalIndexSize = 0;
  for (const file of packedFiles) {
    totalIndexSize += 4; // file_size (int32)
    totalIndexSize += 1; // is_compressed (int8)
    totalIndexSize += Buffer.byteLength(file.name + "\0", "utf8"); // filename + null terminator
  }
  // Create buffer for entire file index and write all at once
  const indexBuffer = Buffer.allocUnsafe(totalIndexSize);
  let offset = 0;
  for (const file of packedFiles) {
    // Write file_size
    indexBuffer.writeInt32LE(file.file_size, offset);
    offset += 4;
    // Write is_compressed flag
    indexBuffer.writeInt8(file.is_compressed ? 1 : 0, offset);
    offset += 1;
    // Write filename with null terminator
    const filenameBytes = Buffer.from(file.name + "\0", "utf8");
    filenameBytes.copy(indexBuffer, offset);
    offset += filenameBytes.length;
  }
  // Single write operation for entire file index
  await outFile.write(indexBuffer);
};
export const readDataFromPacks = async (mods: Mod[]) => {
  // console.log("READ PACKS STARTED");
  // mods = mods.filter((mod) => mod.name === "!!pj_test1.pack" || mod.name === "!!pj_test1_dupe.pack");