BIT STREAM PROCESSING UNIT

PURPOSE: A bit stream processing unit is provided to be capable of storing bit stream header and data in one circular buffer without separating the bit stream header and data. CONSTITUTION: A circular buffer(100) stores a transferred bit stream. Head pointer and read pointer backup registers(110, 120) store such address information that the transferred bit stream is stored. A read pointer register(130) points a position(X) at which a bit stream is read from the circular buffer(100). A bit amount register(140) stores the number of bits to be read from the circular buffer(100). An adder(150) a bit number of the bit amount register(140) to a bit number shifted at a previous step. A control part(160) determines a bit number to be aligned in response to an output of the adder(150). A shift amount register(170) stores an output(a shift amount) of the control part(160). A remain register(180) stores the contents of the circular buffer(100) at a position of 'X-1'. A shift circuit(200) shifts the contents of the circular buffer(100) pointed by the read pointer register(130) and a value of the remain register(180) by a shift amount of the control part(160), so that a desired bit is aligned into a right direction. A masking circuit part(210) masks a value except for desired bits among a result of the shift circuit(200) with '0', in response to a value of the bit amount register(140).