Alphabet-partitioned codewords, for example class based codewords, are decoded using a two-part decoder. The first part is a class code decoder that extracts, from the codeword, information for decoding the symbol code. The second part is a symbol code decoder that uses that information to decode the symbol code. If the symbol code is a literal, the symbol is just stripped from the codeword; otherwise, the symbol is retrieved from a symbol memory. Throughput of blocks of even numbers of codewords is enhanced by compressing first and second block halves oppositely and by using two decoders to decompress first and second block halves in parallel. Throughput is enhanced further by using extended codewords, each of which is a concatenation of class codes and symbol codes of several symbols.