Processor for character strings of variable length

US5761521A · kind A · utility

Assignee

• International Business Machines Corporation · US

Inventors

• Herbert Chilinski · Schenefeld, DE
• Klaus J. Getzlaff · Schenefeld, DE
• Wilhelm Haller · Winnenden, DE
• Ralph C. Koester · Lörrach, DE

Key dates

• Filing date: Mar 26, 1996
• Grant date: Jun 2, 1998
• Expiry date: Mar 26, 2016

Classification

• Technology area (CPC G): Physics
• CPC primary: G06F7/026
• WIPO field: Computer technology
• WIPO sector: Electrical engineering

Abstract

A processor for character strings A, B of variable length serves for the fast detection of match, mismatch and comparative difference conditions between them. The character strings, whose lengths are delimited by character string termination marks, are split into consecutive substrings with a byte count corresponding to the data path width, and processed to detect a match, a mismatch and an end-of-byte mark. Each substring is routed via operand registers (16,18) in parallel to an arithmetic unit (20), a logic unit (22) and a comparator unit (24) and simultaneously processed. The arithmetic unit (20) subtracts one substring from the other substring, the logic unit (22) compares both substrings with each other and the comparator unit (24) compares the bytes of both substrings with the contents of a marking register (26), previously set to the end-of-string mark. These operations are executed in one machine cycle. Output signals from the comparator unit serve to indicate the equality of both substrings, output signals from the logic unit serve to indicate the inequality of both substrings and a carry signal from the arithmetic unit serves at the same time to indicate which of the two …