Shifter circuit that emulates a barrel shifter
US5761266A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Nov 22, 1996 |
| Grant date | Jun 2, 1998 |
| Priority date | — |
| Expiry date | Nov 22, 2016 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG11C19/00
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
A shifting circuit operates on a plurality of input sub-words, that collectively constitute an input data word, to generate a plurality of result sub-words that collectively represent the input data word, shifted. The shifting circuit receives, during each cycle, a separate one of the plurality of input sub-words. A combiner/selector performs a shift on each sub-word provided on the I-bus, taking carry-in bits from a carry-in register. Before a shifting operation is executed, the carry-in register is initialized to zero. (Alternately, the carry-in register may be reset to zero after a shifting operation is executed.) The carry-in register is also connected to receive the sub-words provided by the data source circuit onto the I-bus. Thus, in a system clock cycle when a particular sub-word on the I-bus is being shifted by the combiner/selector, the carry-in register is holding (and providing to the combiner/selector as a source of carry-in bits) the sub-word provided from the carry-in register is the sub-word that was on the I-bus during the previous system clock cycle (except that when the sub-word being shifted is the first sub-word being shifted, the bits of the sub-word provided …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.