Efficient erasure decoding of Reed-Solomon codes

We present a practical algorithm to decode erasures of Reed-Solomon codes over the q elements binary field in O(q log 2 q) time where the constant implied by the O-notation is very small. Asymptotically fast algorithms based on fast polynomial arithmetic were already known, but even if their complexity is similar, they are mostly impractical. By comparison our algorithm uses only a few Walsh transforms and has been easily implemented.