Abstract: A programmable motion estimator includes one dual ported memory for storing an image block, the prediction error, and a temporary block used in interpolation, and a pixel-group random access dual ported memory for storing a search window. The two ports of the two memories are selectively applied to an arithmetic logic unit, or ALU, through a multiplexer. One output of the ALU provides an absolute difference, which is furnished to a tree adder. Another output of the ALU provides an average value or a difference value, as selected, which is routed to the inputs of the image memory and the search memory. In motion vector searching, the ALU performs pixel absolute difference arithmetic using the pixel groups from the image memory and from the search memory, and determines a sum of absolute differences in the tree adder. In half pixel interpolation, the ALU performs pixel averaging arithmetic using pixel groups from the search memory, and writes back to the search memory.

Abstract: A vision processor includes a control section, a motion estimation section, and a discrete cosine transform ("DCT") section. The motion estimation section includes two memories, an image memory with two read ports and a write port, and a search memory with two read ports and a write port. The DCT section includes a DCT memory configurable as a two read, two write port memory and as a four read, four write port memory. The ports of these memories are selectively applied to various elements in the motion estimation path and the DCT path. In motion vector searching, the ALU performs averaging and difference operations on pixels in the frame and search memories. Data from the search memory is shifted for certain operations, before arithmetic operations in the ALU are performed.

Abstract: A content addressable memory is provided that includes a memory cell and a first plurality of lines connected directly to the gates of access transistors to this memory cell. These access transistors are further connected to a second plurality of lines. The first and second plurality of lines each perform different functions during read, write, and comparison modes. In another embodiment of the present invention, p-channel transistors are used for a match transistor and its associated pass transistors.

Abstract: A data compression/decompression processor implements a modified Ziv-Lempel ("LZ") coding technique. The processor includes three modules, an interface, a coder-decoder ("CODEC"), and a MODEL. The CODEC and the MODEL modules together form compression engine, in which the CODEC provides variable length coding and data packing, and the MODEL implements the LZ processing. The MODEL uses content addressable memory ("CAM") in encoding mode for text storage and character matching, and uses CAM in decoding mode as an on-chip RAM to obtain high speed access.