Efficient accuracy check for Newton-Raphson divide and square-root operations
US7689642B1 · kind B1 · utility
Assignee
Inventor
Key dates
| Filing date | Nov 3, 2005 |
| Grant date | Mar 30, 2010 |
| Priority date | — |
| Expiry date | Jan 28, 2029 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F2207/5355
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
One embodiment of the present invention provides a system that efficiently performs an accuracy-check computation for Newton-Raphson divide and square-root operations. During operation, the system performs Newton-Raphson iterations followed by a multiply for the divide or square-root operation. This result is then rounded to produce a proposed result. Next, the system performs an accuracy-check computation to determine whether rounding the result to a desired precision produces the correct result. This accuracy-check computation involves performing a single pass through a multiply-add pipeline to perform a multiply-add operation. During this single pass, a Booth encoding of an operand in a multiply portion of the multiply-add pipeline is modified, if necessary, to cause an additional term for the accuracy-check computation to be added to the result of the multiply-add operation. In this way, the accuracy-check computation can be completed without requiring an additional pass through the multiply-add pipeline and without an additional partial-product row in the multiply-add pipeline.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.