Hardware assist for YUV data format conversion to software MPEG decoder

A display controller assists a host processor in decoding MPEG data. The display controller receives YUV data in non-pixel video format from a host CPU and perform the otherwise CPU intensive task of rasterization within the display controller. In addition, the display controller may use its internal BITBLIT engine to copy U and V data from one line in a BITBLIT operation to adjacent lines, so as to replicate U and V data. A byte mask preserves Y data on the adjacent lines from being overwritten. At the end of the BITBLIT operation, the display controller generates a signal indicating that the frame buffer has been filled with new data, and thus display controller automatically switches to reading from the newly written frame buffer. A display controller for receiving video data from a data bus in a component YUV format and storing the video data to a display memory in a pixel video format, said display controller comprising: bus interface means, coupled to the data bus, for receiving video data in a componen