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CADAC: a controlled-precision decimal arithmetic unit

Journal Article · · IEEE Trans. Comput.; (United States)

The design of an arithmetic unit called CADAC (clean arithmetic with decimal base and controlled precision) is described. Programming language specifications for carrying out ideal floating-point arithmetic are described first. These specifications include detailed requirements for dynamic precision control and exception handling, along with both complex and interval arithmetic at the level of a programming language such as Fortran or PL/1. CADAC is an arithmetic unit which performs the four floating-point operations add/subtract/multiply/divide on decimal numbers in such a way as to support all the language requirements efficiently. A three-level pipeline is used to overlap two-digit-at-a-time serial processing of the partial products/remainders. Although the logic design is relatively complex, the performance is efficient, and the advantages gained by implementing programmer-controlled precision directly in the hardware are significant. 6 references.

Research Organization:
Univ. of Toronto, Ontario, Canada
OSTI ID:
5342548
Journal Information:
IEEE Trans. Comput.; (United States), Journal Name: IEEE Trans. Comput.; (United States) Vol. 4; ISSN ITCOB
Country of Publication:
United States
Language:
English

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