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GENERATION OF ANTILOGS GF(2m)

IP.com Disclosure Number: IPCOM000063008D
Original Publication Date: 1985-Jan-01
Included in the Prior Art Database: 2005-Feb-18

Publishing Venue

IBM

Related People

Authors:
Heise, NN [+details]

Abstract

This method provides for implementing an error correction code logarithm with a compact table. The length of the antilog table is decreased by including the routine in the processor error correction program. Error correction procedures require additional and multiplication of elements in Galois fields. One method of multiplication in GF(2m) is by the modulus (2m-1) addition of the logs of the multiplicands. Mathematically, the multiplication of two elements, A and B, is written: C = Antilog {(log A + log B) modulus 255} A typical calculation that must be done in double burst correction is: s1 = (S-2 S1 + S-1 S0 / S-2 S0 + S-12) S1, S0, S-1 and S-2 are syndrome bytes, which are elements of GF(28). Two 255-byte tables are required: one for the log and one for the antilog.