Method and device for compressing and decompressing digital data

PROBLEM TO BE SOLVED: To compress and decompress data without requiring a corresponding data process or process time by compressing an input data stream into a compressed data stream according to the bits of an input word, and decompressing it into an output data stream. SOLUTION: The input data stream on a line 12 is inputted to an input register 16. The input data stream consists of a series of input words, each of which has 32-bit size. A processor 18 judges whether a data word inputted to the register includes at least one non-zero bit. When the input data word have a value whose one bit is not zero, the processor 18 inputs the input data word to a binary register 22 and the next input data word to a register 16, and marks a proper bit of a control word includes in a control word register 24. A compressing circuit 10 compress the input data stream into a compressed stream consisting of at least one control word. An decompressing circuit decompresses the compressed data stream and outputs the output data stream.