Module gf 

GF(2^16) Galois field arithmetic.

PAR2 mandates the irreducible polynomial 0x1100B: x^16 + x^12 + x^3 + x + 1

All arithmetic uses log/antilog (exp) tables for O(1) multiply/divide. The generator element is 2 (as per the PAR2 spec).

Functions

add

Addition in GF(2^16) is XOR.

div

Divide a by b in GF(2^16). Panics if b is 0 (division by zero).

exp2

Return 2^exp in GF(2^16). The generator is 2.

inv

Multiplicative inverse: inv(a) = a^(FIELD_ORDER-1) = a^65534. Panics if a is 0.

mul

Multiply two elements in GF(2^16). Returns 0 if either operand is 0.

pow

Raise a to the power exp in GF(2^16).

sub

Subtraction in GF(2^16) is the same as addition (XOR).