Circuit and method for determining multiplicative inverses with a look-up table
US5818744A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 2, 1994 |
| Grant date | Oct 6, 1998 |
| Priority date | — |
| Expiry date | Feb 2, 2014 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB60T8/17616
- WIPO fieldTransport
- WIPO sectorMechanical engineering
Abstract
Digital circuits determine multiplicative inverses using look-up tables which, in response to an address signal, provide a signal indicating a multiplicative inverse. The look-up tables store values indicating inverses for numbers between 1 and 2. The circuit factors a value to be inverted as product a power of two and a factor between 1 and 2. An address signal indicating the factor is applied to the look-up table, and the look-up table provides a signal which indicates the inverse of the factor. The signal provided by the look-up table is then converted to the proper scale for the exponent N. Factoring and conversion may be accomplished with logical shifts so that no multiplier is required. The look-up table may be compressed by not storing bits of inverses, which are constant or only change once within the range of the look-up table and by only storing look-up values for every other number within the range of the look-up table. A code bit in each look-up table value permits generation of correct inverses for values not stored.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.