The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Aug. 27, 1996
Filed:
Jan. 31, 1995
Clarence R Ogilvie, Huntington, VT (US);
Paul C Stabler, Huntington, VT (US);
International Business Machines Corporation, Armonk, NY (US);
Abstract
A method and apparatus for parallel 'normalize-round-normalize' floating point arithmetic. The rounding-normalizer of the invention receives as an input an infinitely precise mantissa which is the result of a floating point operation. This infinitely precise result mantissa is broken into two fields, the Close Enough Bits, and the Picky Bits. These bits are selectively passed to four parallel data paths for taking close enough bits and picky bits and producing a correctly rounded mantissa. The paths are, respectively; (a) a 1X.XX . . . X data path for mantissas greater than or equal to 2 but less than 4, the data path right shifting the upper bits and adjusting the exponent by +1 or +2; (b) a 01.XX . . . X data path for mantissas greater than or equal to 1 but less than 2, the data path right shifting the upper bits and adjusting the exponents by +0 or +1; (c) a 00.1X . . . X data path for mantissas greater than or equal to 1/2 but less than 1, the data path left shifting bits and adjusting the exponent by -1 or +0; and (d) a 00.01X . . . X data path for mantissas less than 1/2, the data path left shifting the bits and adjusting the exponent by the shift amount. Each of the data paths produces a normalized and rounded mantissa for its subset of mantissas.