The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 20, 2004
Filed:
Dec. 21, 2000
Robert L. Hoffman, Santa Clara, CA (US);
Jonathan M. Parlan, Los Altos, CA (US);
Cisco Technology, Inc., San Jose, CA (US);
Abstract
Methods and apparatus are disclosed for generating and checking CRC values using a multi-byte CRC generator and a binary Galois field (“GF2”) multiplier. These methods and apparatus could be used in an unlimited number of applications and environments, such as part of computer or communications device (e.g., router or switch). The CRC generator and/or checker may be implemented singularly or in a combination of technologies, including, but not limited to, software, firmware, hardware, customized circuitry, application-specific integrated circuits, etc. A CRC generator is used to calculate a preliminary CRC value on a block of information. This CRC generator may be a balanced XOR tree or some other implementation, which calculates the preliminary CRC value on groups of n bytes of data at a time, where n is some integer greater than one. For example, when data is transferred over a 512 wide bit bus, typically the value of n would be 64 (i.e., 512 bits divided by 8 bits per byte). Because the number of bytes in the data group may not be an even multiple of the value of n, one or more bytes of value zero may be appended to the data group to make it an even multiple, with the preliminary CRC being calculated on the entire appended data group. A GF2 multiplier uses the preliminary CRC value and the number of appended bytes of value zero to calculate the actual CRC value of the information.