Graphics engine fifo interface architecture

Abstract

A Graphics Engine (GE) FIFO interface architecture that allows the transfers of reduced address information from the GE to the frame buffer is provided. The FIFO interface architecture further allows the GE to be isolated from the Memory Interface Unit (MIU) or the Central Processor Interface Unit (CIF) such that the GE can operate at a different frequency from the MIU and the CPU. Address information is provided using two flag bits End of Line (EOL) and Add One (AO). In write mode, flag bits EOL and AO are used to determine the next address in the frame buffer where processed data from the GE is to be stored. In line draw mode, flag bits EOL and AO are used to determine the address in the frame buffer for data retrieval. Such data retrieval allows a rendered line to perform background and foreground color ROP in line draw commands. Flag bit EOL indicates whether the GE needs to skip to the next scan line (e.g., the end of the current scan line has been reached). Flag bit AO indicates whether an offset value needs to be added/subtracted to the present address in determining the next address.