66 lines
1.8 KiB
C++
66 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 __FIELD_READER_H__
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#define __FIELD_READER_H__
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#include <cstdint>
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#include <cstddef>
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struct BitRemapNone {
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constexpr size_t operator()(const size_t& bit_index) const {
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return bit_index;
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}
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};
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struct BitRemapByteReverse {
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constexpr size_t operator()(const size_t bit_index) const {
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return bit_index ^ 7;
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}
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};
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template<typename T, typename BitRemap>
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class FieldReader {
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public:
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constexpr FieldReader(
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const T& data
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) : data { data }
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{
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}
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/* The "start_bit" winds up being the MSB of the returned field value. */
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/* The BitRemap functor determines which bits are read from the source
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* packet. */
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int32_t read(const size_t start_bit, const size_t length) const { //Euquiq: was uint32_t, used for calculating lat / lon in radiosondes, can be negative too
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uint32_t value = 0;
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for(size_t i=start_bit; i<(start_bit + length); i++) {
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value = (value << 1) | data[bit_remap(i)];
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}
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return value;
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}
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private:
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const T& data;
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const BitRemap bit_remap { };
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};
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#endif/*__FIELD_READER_H__*/
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