nand_calculate_ecc_kw() function

Reed-Solomon code This implements a (1023,1015) Reed-Solomon ECC code over GF(2^10) mod x^10 + x^3 + 1, shortened to (520,512). The ECC data consists of 8 10-bit symbols, or 10 8-bit bytes. Given 512 bytes of data, computes 10 bytes of ECC. This is done by converting the 512 bytes to 512 10-bit symbols (elements of F), interpreting those symbols as a polynomial in F[X] by taking symbol 0 as the coefficient of X^8 and symbol 511 as the coefficient of X^519, and calculating the residue of that polynomial divided by the generator polynomial, which gives us the 8 ECC symbols as the remainder. Finally, we convert the 8 10-bit ECC symbols to 10 8-bit bytes. The generator polynomial is hardcoded, as that is faster, but it can be computed by taking the primitive element a = x (in F), and constructing a polynomial in F[X] with roots a, a^2, a^3, ..., a^8 by multiplying the minimal polynomials for those roots (which are just 'x - a^i' for each i). Note: due to unfortunate circumstances, the bootrom in the Kirkwood SOC expects the ECC to be computed backward, i.e. from the last byte down to the first one.

Found 168 other functions taking a nand_device argument: