Cesari & McKenna
Combined system for producing error correction code symbols and error syndromes
 A combined encoding/syndrome generating circuit is segmented into multiple-cell blocks that operate in parallel during encoding operations to produce interim sums. The interim sums are then combined to propagate a sum across the system, from the first cell to the last cell. Each cell includes a Galois Field multiplier and an associated update adder and register. A block of two cells includes two sets of associated Galois Field multipliers, registers and update adders, and a block feedback adder that produces the associated interim sum by adding together the products produced in parallel by each of the cells. A block with more than two cells includes additional feedback adders that operate in parallel to selectively combine the products produced by the plurality of cells, and produce an interim sum that includes a contribution from each of the cells in the block. The system then adds together the interim sums produced simultaneously by the various blocks, to propagate a sum across the system. Also, the interim sum from a given block is combined in parallel into the products produced by the respective cells of the next block, to include in the update signals that are fed back to the associated registers the contributions from each of the previous cells. During syndrome generation operations, the cells essentially operate independently to produce the syndromes. The current system includes more feedback adders than the conventional Fettweis-Hassner circuit, however, the delay through the current system is reduced from that of the conventional system, since many of the feedback adders in the current system operate in parallel. 
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inventional inventional
Lih-Jyh Chung-Hsing Ba-Zhong Shih
Weng Chang Shen Mo