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:
Jan. 19, 1999
Filed:
Jul. 19, 1995
David William Matula, Dallas, TX (US);
Debjit Das Sarma, Dallas, TX (US);
National Semiconductor Corporation, Santa Clara, CA (US);
Abstract
A bipartite compression technique is used to implement a bipartite reciprocal table that provides seed reciprocal values for multiplicative (reciprocal refinement) division. The bipartite reciprocal table (12) includes component tables P and N. The input table index is partitioned into high, middle, and low order parts �x.sub.h .vertline.x.sub.m .vertline.x.sub.1 !'the high and middle order parts �x.sub.h .vertline.x.sub.m ! index the P Table, and the high and low order parts �x.sub.h .vertline.x.sub.1 ! index the N Table. The P and N Tables provide first and second component outputs which form a redundant output from the bipartite lookup table. The bipartite table output may be (a) optimal in that, for each entry in each table, the maximum relative error is the minimum possible, and/or (b) when fused with rounding, faithful (i.e., accurate to one unit in the last place). In an exemplary implementation, the bipartite reciprocal table is used in combination with a Booth recoded multiplier --the redundant borrow-save output from the bipartite table is input directly to the Booth recoder, such that the Booth recoder performs a fusion of the first and second component outputs.