3.2.4.2.2. BCH Decoder parameters¶

3.2.4.2.2.1. --dec-type, -D¶

Type: text ALGEBRAIC CHASE ML ALGEBRAIC --dec-type ALGEBRAIC

Select the decoder algorithm.

Description of the allowed values:

Value Description
ALGEBRAIC Select the Berlekamp-Massey algorithm [Ber15][Mas69] followed by a Chien search [Chi64].
CHASE See the common --dec-type, -D parameter.
ML See the common --dec-type, -D parameter.

3.2.4.2.2.2. --dec-implem¶

Type: text FAST GENIUS STD STD --dec-implem FAST

Select the implementation of the decoder algorithm.

Description of the allowed values:

Value Description
STD A standard implementation of the BCH.
FAST Select the fast implementation optimized for SIMD architectures.
GENIUS A really fast implementation that compare the input to the original codeword and correct it only when the number of errors is less or equal to the BCH correction power.

Note

In the STD implementation, the Chien search finds roots of the error location polynomial. If the number of found roots does not match the number of found errors by the BM algorithm, then the frame is not modified.

However, in the FAST implementation the correction of the bits is done at the same time as the execution of the Chien search. Then when the latter fails, the frame can be modified.

Note

When a frame is very corrupted and when the above STD and FAST implementations can be wrong in the correction by converging to another codeword, the GENIUS implementation cannot fail. Results may then differ from a real word implementation.

3.2.4.2.2.3. --dec-corr-pow, -T¶

Type: integer 5 --dec-corr-pow 18

Set the correction power of the BCH decoder. This value corresponds to the number of errors that the decoder is able to correct.

3.2.4.2.2.4. References¶

 [Ber15] E. R. Berlekamp. Algebraic Coding Theory (Revised Edition). World Scientific, May 2015. First edition from 1968. doi:10.1142/9407.
 [Chi64] R. Chien. Cyclic decoding procedures for bose- chaudhuri-hocquenghem codes. IEEE Transactions on Information Theory (TIT), 10(1):357–363, October 1964. doi:10.1109/TIT.1964.1053699.
 [Mas69] J. Massey. Shift-register synthesis and bch decoding. IEEE Transactions on Information Theory (TIT), 15(1):122–127, January 1969. doi:10.1109/TIT.1969.1054260.