Function bch_correct_regular 

pub fn bch_correct_regular(
    hrp: &str,
    data_with_checksum: &[u8],
) -> Result<CorrectionResult, Error>

Attempt to correct a regular-code BCH-checksummed string with up to four substitutions, the full t = 4 capacity of the BCH(93, 80, 8) code.

Implements the standard syndrome-based BCH decoder pipeline: syndrome computation in GF(1024) = GF(32²), Berlekamp–Massey for the error-locator polynomial, Chien search for error positions, Forney’s algorithm for error magnitudes. After applying the proposed corrections, the result is re-verified via bch_verify_regular; the decoder rejects any output that does not produce a valid codeword (defensive guard against pathological 5+-error inputs whose syndromes happen to factor as a degree-≤ 4 locator).

Returns Ok(CorrectionResult) if the input is clean or up to four substitutions repair it. Returns Err(Error::BchUncorrectable) otherwise.

Algorithm details

See the private bch_decode submodule for the algorithm and the GF(1024) field representation.