Equivalence verification of arithmetic datapaths with multiple word-length operands

  • Authors:
  • Namrata Shekhar;Priyank Kalla;Florian Enescu

  • Affiliations:
  • University of Utah, Salt Lake City, UT;University of Utah, Salt Lake City, UT;Georgia State University, Atlanta, GA

  • Venue:
  • Proceedings of the conference on Design, automation and test in Europe: Proceedings
  • Year:
  • 2006

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Abstract

This paper addresses the problem of equivalence verification of RTL descriptions that implement arithmetic computations (add, mult, shift) over bit-vectors that have differing bit-widths. Such designs are found in many DSP applications where the widths of input and output bit-vectors are dictated by the desired precision. A bit-vector of size n can represent integer values from 0 to 2n -- 1; i. e. integers reduced modulo 2n. Therefore, to verify bit-vector arithmetic over multiple word-length operands, we model the RTL datapath as a polynomial function from Z2n1 XZ 2n2 X . . . X . . . Z2nd to Z2m. Subsequently, RTL equivalence f ≡ g is solved by proving whether (f -- g) ≡ 0 over such mappings. Exploiting concepts from number theory and commutative algebra, a systematic, complete algorithmic procedure is derived for this purpose. Experimentally, we demonstrate how this approach can be applied within a practical CAD setting. Using our approach, we verify a set of arithmetic datapaths at RTL where contemporary approaches prove to be infeasible.