On-the-Fly Rounding (Computing Arithmetic)

  • Authors:
  • M. D. Ercegovac;T. Lang

  • Affiliations:
  • -;-

  • Venue:
  • IEEE Transactions on Computers
  • Year:
  • 1992

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Abstract

In implementations of operations based on digit-recurrence algorithms such as division, left-to-right multiplication and square root, the result is obtained in digit-serial form, from most significant digit to least significant. To reduce the complexity of the result-digit selection and allow the use of redundant addition, the result-digit has values from a signed-digit set. As a consequence, the result has to be converted to conventional representation, which can be done on-the-fly as the digits are produced, without the use of a carry-propagate adder. The authors describe three ways to modify this conversion process so that the result is rounded. The resulting operation is fast because no carry-propagate addition is needed. The schemes described apply also to online arithmetic operations.