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52 lines
900 B
C++
52 lines
900 B
C++
// Copyright 2020 Mobilinkd LLC.
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#pragma once
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#include <array>
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#include <cstdint>
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#include <cstddef>
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#include "export.h"
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namespace modemm17
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{
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struct MODEMM17_API M17Randomizer
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{
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std::array<int8_t, 368> dc_;
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M17Randomizer()
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{
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size_t i = 0;
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for (auto b : DC)
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{
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for (size_t j = 0; j != 8; ++j)
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{
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dc_[i++] = (b >> (7 - j)) & 1 ? -1 : 1;
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}
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}
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}
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// Randomize and derandomize are the same operation.
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void operator()(std::array<int8_t, 368>& frame)
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{
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for (size_t i = 0; i != 368; ++i)
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{
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frame[i] *= dc_[i];
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}
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}
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void randomize(std::array<int8_t, 368>& frame)
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{
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for (size_t i = 0; i != 368; ++i)
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{
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frame[i] ^= (dc_[i] == -1);
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}
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}
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private:
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static const std::array<uint8_t, 46> DC;
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};
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} // modemm17
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