System for finding and setting address portion of variable-length character string by XOR-ing portion in number of bytes within single instruction
US5495592A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jan 6, 1995 |
| Grant date | Feb 27, 1996 |
| Priority date | — |
| Expiry date | Jan 6, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG06F16/90344
- WIPO fieldComputer technology
- WIPO sectorElectrical engineering
Abstract
The invention is an instruction for locating the address of a specific character or value within a byte string of variable length. An offset into a portion of the string is specified and the portion of the string is searched for a first occurrence of the specific character beginning at the specified offset. If the specific character is found, then the existence of the specific character is indicated and an address or offset of the specific character is saved or otherwise indicated. If the specific character is not found, then the non-existence of the specific character is indicated and a convenient address or offset for referencing the next character immediately following the portion of the string already examined is saved or otherwise indicated. The specific character can have a length of one or more bytes and can be a pre-defined fixed value or a dynamic arbitrary value. The invention can execute in a time period comparable to performing an arithmetic instruction. Moreover, the invention can be combined with other load and store instructions, so that a copy operation can be performed by invoking this instruction sequence one or more times.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.