Importance

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Abstract

A summation unit device suitable for the cumulative summation of integer and/or floating point format data presented to an input thereof. The device is particularly useful as an adjunct to a relational database co-processor, receiving data therefrom relating to a plurality of different columns of a database table for the independent summation of the different columns. The data is received on a byte-by-byte basis, and summation takes place in 'quasi-realtime' on each byte as it is presented at the device input. A number of running totals are generated which may be output at the end of the database query. The device uses a register for storing a plurality of running totals, a byte-adder for summing each new data-byte with a respective byte from the running totals register, and byte- and bit-shifting operations to correctly align floating point mantissa during summation in accordance with an exponent difference value determined from the respective running total and new floating point format data. The pipelined architecture of the device allows for selection of respective bytes from two numeric additives according to the exponent difference value and delay-less bit shifting of one such byte in accordance with the exponent difference value to provide two operands. Successive bytes are provided to be summed, with latching to wrap-around residual bits from preceding bytes.

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First Claim