| 摘要 |
A bidirectional code decoding method and apparatus is presented. It uses a class of Reed-Solomon codes capable of bidirectional decoding, more specifically, those for which a value of L for a Galois Field element alpha<L >is chosen as -(R-1)/2 for odd values of R and 2<(m-1)>-R/2 for even values of R. When the symbols of such codes are received at a decoder in a reverse order (from that in which the symbols are normally received) during a reverse directional read, the decoder produces reverse directional syndromes S<~>(-k) and converts the reverse directional syndromes S<~>(-k) to syndromes S(k) by multiplying S<~>(-k) by alpha<(n-1)k >for k=L, L+1, . . . , L+R-1. Alternatively, the decoder adjusts error location values for errors occurring in reverse order code word symbols to correspond to error location values that correspond to an error locations that would be determined if the symbols were to be received in the order in which the symbols are normally received.
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