Nikaido, Marmelstein, Murray & Oram
Floating-point arithmetic system having multiple-input addition and subtraction means
 A floating-point arithmetic system, which allows arithmetic operations, including at least addition and subtraction, to be performed for floating-point data. The system includes multiple-input addition and subtraction devices for executing adding and subtracting calculations of at least three floating-point data. Preferably, the multiple-input addition and subtraction devices includes a multiple-input device which enables at least three floating-point data to be input, a shift-amount determining device having a look up table which compares the respective exponents in parallel, selects the maximum exponent and determines the amount of shift in the respective mantissas; and a mantissa shifting devices, e.g., at least one multiplexer, which shifts the respective mantissas in accordance with the amount of shift and makes an adjustment of digit positions of the mantissas. The system also includes at least one multiple-input adder-subtractor which executes addition and subtraction for the mantissas output from the mantissa shifting device, and a normalization circuit which normalizes a result obtained by the multiple-input adder-subtractor. 
Fujitsu Limited
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additional additional inventional inventional
Hideki Katsuhito Tatsushi
Yoshizawa Fujimoto Otsuka