A Combined Decimal and Binary Floating-Point Multiplier

  • Authors:
  • Charles Tsen;Sonia Gonzalez-Navarro;Michael Schulte;Brian Hickmann;Katherine Compton

  • Affiliations:
  • -;-;-;-;-

  • Venue:
  • ASAP '09 Proceedings of the 2009 20th IEEE International Conference on Application-specific Systems, Architectures and Processors
  • Year:
  • 2009

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Abstract

In this paper, we describe the first hardware design of a combined binary and decimal floating-point multiplier, based on specifications in the IEEE 754-2008 Floating-point Standard. The multiplier design operates on either (1) 64-bit binary encoded decimal floating-point (DFP) numbers or (2) 64-bit binary floating-point (BFP) numbers. It returns properly rounded results for the rounding modes specified in IEEE 754-2008. The design shares the following hardware resources between the two floating-point datatypes: a 54-bit by 54-bit binary multiplier, portions of the operand encoding/decoding, a 54-bit right shifter, exponent calculation logic, and rounding logic. Our synthesis results show that hardware sharing is feasible and has a reasonable impact on area, latency, and delay.The combined BFP and DFP multiplier occupies only 58% of the total area that would be required by separate BFP and DFP units. Furthermore, the critical path delay of a combined multiplier has a negligible increase over a standalone DFP multiplier, without increasing the number of cycles to perform eitherBFP or DFP multiplication.