US Patent 7286066 Acceleration of bitstream decoding

Described are methods and systems for variable length decoding. A first execution unit executes a first single instruction that optionally reverses the order of bits in an encoded bitstream. A second execution unit executes a second single instruction that extracts a specified number of bits from the bitstream produced by the first execution unit. A third execution unit executes a third single instruction that identifies a number of consecutive zero bit values at the head of the bitstream produced by the first execution unit. The outputs of the first, second and third execution units are used in a process that decodes the encoded bitstream.