Method and apparatus for detection and error correction of packetized

Abstract

Digital data is stored in a buffer, and a data buffer CRC word is generated for error detection. Error correction is provided by a set of XPQ circular queues ('XPQs') used to compute an error correction syndrome. As each word is loaded into the data buffer, it is also XORed into each of the XPQs. An XPQ CRC is generated for error detection in the XPQs. The complete data packet may be transmitted or stored for later retrieval. Upon receipt or retrieval, the packet is decoded and checked for errors. The incoming data is read into a second buffer and a new CRC is generated. If the incoming CRC matches the new CRC, no errors exist and no further checking or correction is needed. If the CRCs do not match, the incoming data is used to generate new XPQ' queues and a new XPQ CRC. If the incoming XPQ CRC matches the new XPQ CRC, then the error may be correctable. XPQ imprinter circular queues ('IQ') are formed by XORing each word of the incoming XPQs with the words of the new corresponding XPQs. Intermediate correction masks are then created by sequentially writing the contents of each IQ to intermediate correction mask buffers. A single XPQ correction mask is then formed by ANDing each corresponding word of each intermediate correction mask buffer together. The correction mask is evaluated and if the errors are determined to be correctable, correction is achieved by XORing each corresponding word in the XPQ correction mask with the incoming data.