The present disclosure includes apparatus, systems and techniques relating to lossless data compression. In some implementations, an apparatus includes a memory module to store data. The memory module includes a first buffer portion to store encoded symbols of the data, and a second buffer portion to store symbols of the data to be encoded. The apparatus includes an encoder to compare the symbols stored in the second buffer portion with the encoded symbols stored in the first buffer portion and to compress the data. The encoder can operate in a first encoding mode to encode the symbols in the second buffer portion with corresponding codewords until detecting a repeated pattern of symbols in the second buffer portion that matches the encoded symbols in the first buffer portion. The encoder can operate in a second encoding mode responsive to detecting the repeated pattern.