Advanced Hardware Architectures, Inc.

Advance Hardware Architecture

Catherine A French

Patrick A Owsley

Kel D Winters

Torkjell Berge

Peter S Feeley

Robert M Bode

Kenneth J Baker

Greg C Zweigle

A sliding window with big gap data compression system is simple to implement and gives good compression over a wide variety of bilevel images. A sliding window compressor with a very small window size is utilized in conjunction with a storage buffer which is large enough to hold at least an entire scan line of data symbols. Coupled to the storage buffer is circuitry that checks for a match between the incoming data symbol and a symbol stored in one specific programmable location. This programmable location is preferably exactly one scan line length away. Match locations are either within the range of the small window or exactly equal to the specific programmable location. The entire compressor can be viewed as a sliding window with a big gap (SWBG). This sliding window is of a length corresponding to the length of the scan line, comprised of the small window followed by a big gap and then the one specific programmable location, at the end of the scan line.

Sliding window with big gap data compression system

An adaptive lossless data compression system with systolic string matching logic performs compression and decompression at the maximum rate of one symbol per clock cycle. The adaptive data compression system uses an improvement of the LZ1 algorithm. A content addressable memory (CAM) is used to store the last n input symbols. The CAM is stationary, stored data is not shifted throughout the CAM, but rather the CAM is used as a circular queue controlled by a Write Address Pointer Counter (WREN). During a compression operation, a new input symbol may be written to the CAM on each clock cycle, while simultaneously the rest of the CAM is searched for the input symbol. Associated with each word of the CAM array is a String Match State Machine (SMSM) and, an address logic module (ALM). These modules detect the occurrence of strings stored in the CAM array that match the current input string and report the address of the longest matching string nearest to the Write Address Pointer. The SMSM modules constitute a systolic logic array, where state information is shifted synchronously in the direction of the Write Address Pointer. The strings are represented by a string code which includes a length value, representing the length of the string, and a position value, representing the position in the CAM of the beginning of the string. During a decompression operation, the single symbols and string codes are input to the system. The symbols are stored in the CAM and the control logic outputs the decompressed data symbols using the stored data and the string codes.

Adaptive data compression system with systolic string matching logic

The present invention is for a Error Correction Unit (ECU) that uses a single stack architecture for the generation, reduction and evaluation of the polynomials involved in the correction of a Reed-Solomon code. The circuit uses the same hardware to generate the syndromes, reduce the .OMEGA.(x) and .LAMBDA.(x) polynomials and evaluate the .OMEGA.(x) and .LAMBDA.(x) polynomials. Some of the specifics involved in calculating and reducing the polynomials mentioned above are novel as well. First, the implementation of the general Galois field multiplier is new and faster than previous implementations. Second, the circuit for implementing the Galois field inverse function has not appeared in prior art designs. Third, a novel method of generating the .OMEGA.(x) and .LAMBDA.(x) polynomials (including alignment of these polynomials prior to evaluation) is utilized. Fourth, corrections are performed in the same order as they are received using a premultiplication step prior to evaluation. Fifth, a novel method of implementing flags for uncorrectable errors is used. Sixth, the ECU is data driven in that nothing happens if no data is present. Finally, interleaved data is handled internally to the chip.

Single-stack implementation of a Reed-Solomon encoder/decoder

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Moscow, ID, United States of America

Catherine A French