39 lines
842 B
C++
39 lines
842 B
C++
#pragma once
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#include <nall/serializer.hpp>
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#include <nall/stdint.hpp>
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namespace nall {
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struct RandomNumberGenerator {
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virtual auto seed(uint64_t) -> void = 0;
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virtual auto operator()() -> uint64_t = 0;
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virtual auto serialize(serializer&) -> void = 0;
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};
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//Galois LFSR using CRC64 polynomials
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struct LinearFeedbackShiftRegisterGenerator : RandomNumberGenerator {
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auto seed(uint64_t seed) -> void {
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lfsr = seed;
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for(uint n = 0; n < 8; n++) operator()();
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}
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auto operator()() -> uint64_t {
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return lfsr = (lfsr >> 1) ^ (-(lfsr & 1) & crc64);
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}
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auto serialize(serializer& s) -> void {
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s.integer(lfsr);
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}
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private:
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static const uint64_t crc64 = 0xc96c'5795'd787'0f42;
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uint64_t lfsr = crc64;
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};
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inline auto random() -> uint64_t {
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static LinearFeedbackShiftRegisterGenerator lfsr;
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return lfsr();
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}
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}
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