Using variable length encoding to compress an input data stream to a compressed output data stream

摘要

Provided are a computer program product, system, method, and data structure for using variable length code tables to compress an input data stream to a compressed output data stream. If a number of consecutive data units in the input data stream match the number of consecutive data units in a history buffer of previously received data units in the input data stream, a copy pointer symbol is generated indicating the copy pointer symbol referencing previously received data units in the history buffer and indicating a location of a start of the consecutive data units in the history buffer. A determination is made of an encoding of the number. Indication is made in the generated copy pointer symbol the determined encoding of the number and the copy pointer symbol is outputted in the compressed output data stream.

主权项

1. A computer program product for compressing an input data stream to produce a compressed output data stream, the computer program product comprising a computer readable storage medium having computer readable program code embodied therein that is executed to perform operations, the operations comprising:
determining whether a number of consecutive data units in the input data stream match the number of consecutive data units in a history buffer of previously received data units in the input data stream; in response to determining that the number of consecutive data units in the input data stream match the number of consecutive data units in the history buffer, generating a copy pointer symbol indicating the copy pointer symbol referencing previously received data units in the history buffer and indicating a location of a start of the consecutive data units in the history buffer; determining an encoding of the number, wherein the encoding includes one of a plurality of prefix values, wherein each prefix value has one or more bits, and wherein the one or more bits of each prefix value indicates a number of data units represented by at least one bit following the prefix value; indicating in the generated copy pointer symbol the determined encoding of the number; and outputting the copy pointer symbol in the compressed output data stream.