74 lines
1.8 KiB
C++
74 lines
1.8 KiB
C++
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/*
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* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
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*
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* This file is part of PortaPack.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2, or (at your option)
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* any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; see the file COPYING. If not, write to
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* the Free Software Foundation, Inc., 51 Franklin Street,
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* Boston, MA 02110-1301, USA.
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*/
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#ifndef __BIT_PATTERN_H__
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#define __BIT_PATTERN_H__
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#include <cstdint>
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#include <cstddef>
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class BitHistory {
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public:
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void add(const uint_fast8_t bit) {
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history = (history << 1) | (bit & 1);
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}
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uint64_t value() const {
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return history;
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}
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private:
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uint64_t history { 0 };
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};
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class BitPattern {
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public:
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constexpr BitPattern(
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) : code_ { 0 },
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mask_ { 0 },
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maximum_hanning_distance_ { 0 }
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{
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}
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constexpr BitPattern(
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const uint64_t code,
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const size_t code_length,
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const size_t maximum_hanning_distance = 0
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) : code_ { code },
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mask_ { (1ULL << code_length) - 1ULL },
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maximum_hanning_distance_ { maximum_hanning_distance }
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{
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}
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bool operator()(const BitHistory& history, const size_t) const {
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const auto delta_bits = (history.value() ^ code_) & mask_;
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const size_t count = __builtin_popcountll(delta_bits);
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return (count <= maximum_hanning_distance_);
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}
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private:
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uint64_t code_;
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uint64_t mask_;
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size_t maximum_hanning_distance_;
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};
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#endif/*__BIT_PATTERN_H__*/
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