Patent · US Expired

Carry-select adder with pre-counting of leading zero digits

US5875123A · kind A · utility

4Cited by

6References

17Claims

0Family size

Assignee

International Business Machines Corporation · US

Inventors

Son Dao Trong · Stuttgart, DE
Gunter Gerwig · Simmozheim, DE
Klaus J. Getzlaff · Schenefeld, DE
Wilhelm Haller · Winnenden, DE

Key dates

Filing date	May 13, 1997
Grant date	Feb 23, 1999
Priority date	—
Expiry date	May 13, 2017

Classification

Technology area (CPC G)Physics
CPC primaryG06F7/485
WIPO fieldComputer technology
WIPO sectorElectrical engineering

Abstract

A method and apparatus for the determination of leading zero digits of a sum is presented herein. The technique incorporates the parallel determination of partial sums of single digits accounting for the possibility of carries and on the basis thereof the pre-determination of potential zero digits or potential leading zero digits. Upon the establishment of a correct partial sum, the potential zero digits are selected and evaluated thereby determining the leading zero digits. The invention may be implemented in an adder in parallel or via a hierarchical structure. The parallelism permits time-savings in the determination of a normalized sum. The invention is preferably incorporated into adders, floating point computing units and/or data processing units.

Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.