/**
* Parse a header from a byte buffer. The buffer's position will be advanced to the end of the
* header.
*
* @param buf The byte buffer.
* @return The header.
*/
public static BinaryHeader fromHeader(ByteBuffer buf) {
Preconditions.checkArgument(buf.remaining() >= HEADER_SIZE, "buffer not large enough");
byte[] magic = new byte[2];
buf.get(magic);
if (!Arrays.equals(magic, BinaryFormat.HEADER_MAGIC)) {
throw new IllegalArgumentException("invalid magic");
}
short word = buf.getShort();
BinaryFormat format = BinaryFormat.fromFlags(word);
int nratings = buf.getInt();
int nusers = buf.getInt();
int nitems = buf.getInt();
return new BinaryHeader(format, nratings, nusers, nitems);
}
