1. A decoding system in a graphics processing unit, comprising: a software programmable core processing unit having a context-adaptive variable length coding (CAVLC) unit capable of performing shader functionality, the shader functionality including implementing CAVLC decoding of a video stream and providing a decoded data output, wherein the CAVLC unit is further configured to use bits in an instruction to determine whether a result of a previous operation stored in an internal register should be used or a data in a source operand should be used for a current operation at one or more modules, wherein the CAVLC decoding is implemented using a combination of software and hardware.