wownero-seed/include/monero_seed/galois_field.hpp

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2020-06-13 19:00:39 +00:00
/*
Copyright (c) 2020 tevador <tevador@gmail.com>
All rights reserved.
*/
#pragma once
#include <cstdint>
#include <cassert>
typedef uint_least16_t gf_storage;
typedef uint_fast16_t gf_item;
template<unsigned bits, gf_item primitive>
class galois_field {
public:
galois_field();
gf_item inverse(gf_item i) const {
assert(i != 0);
return i > 1 ? inv_table[i] : 1;
}
gf_item mult(gf_item a, gf_item b) const {
if (b == 0 || a == 0)
return 0;
if (b == 1)
return a;
if (a == 1)
return b;
return exp_table[log_table[a] + log_table[b]];
}
gf_item exp(gf_item i) const {
return exp_table[i];
}
static constexpr unsigned size() {
return bits;
}
static constexpr unsigned elements() {
return size_;
}
private:
static_assert(bits <= 14, "field is too large");
static constexpr gf_item size_ = 1u << bits;
gf_storage log_table[size_];
gf_storage exp_table[2 * size_];
gf_storage inv_table[size_];
};
using gf_2048 = galois_field<11, 2053>;