mirror of
https://github.com/eried/portapack-mayhem.git
synced 2024-12-25 07:19:28 -05:00
237 lines
7.4 KiB
C++
237 lines
7.4 KiB
C++
/*
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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 __BASEBAND_AIS_H__
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#define __BASEBAND_AIS_H__
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#include "crc.hpp"
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#include <cstdint>
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#include <cstddef>
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#include <complex>
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#include <array>
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#include <bitset>
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namespace baseband {
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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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uint32_t read(const size_t start_bit, const size_t length) {
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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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namespace ais {
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// RRC length should be about 4 x the symbol length to do a good job of
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// cleaning up ISI.
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/*
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constexpr std::array<std::complex<float>, 8> rrc_taps_8_p { {
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{ 0.00533687f, 0.00000000f }, { -0.00667109f, 0.00667109f },
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{ 0.00000000f, 0.01334218f }, { -0.05145006f, -0.05145006f },
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{ -0.14292666f, 0.00000000f }, { -0.05145006f, 0.05145006f },
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{ 0.00000000f, -0.01334218f }, { -0.00667109f, -0.00667109f },
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} };
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*/
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//
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// These came from GRC directly, and have a bit more gain, it appears.
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//
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constexpr std::array<std::complex<float>, 8> rrc_taps_8_p { {
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{ 2.1046938375e-02f, 0.0000000000e+00f }, { -2.6308671336e-02f, -2.6308671336e-02f },
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{ -3.2218829289e-18f, -5.2617341280e-02f }, { -2.0290270482e-01f, 2.0290270482e-01f },
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{ -5.6365746260e-01f, 6.9028130738e-17f }, { -2.0290270482e-01f, -2.0290270482e-01f },
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{ 9.6656487867e-18f, 5.2617341280e-02f }, { -2.6308671336e-02f, 2.6308671336e-02f },
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} };
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constexpr std::array<std::complex<float>, 16> rrc_taps_16_p { {
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{ -5.0682835281e-03f, 0.0000000000e+00f }, { 3.8012127427e-03f, 3.8012127427e-03f },
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{ 9.3102863700e-20f, 1.5204851516e-03f }, { 5.3216978397e-03f, -5.3216978397e-03f },
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{ -2.1286793053e-02f, 2.6068802977e-18f }, { 2.6608490845e-02f, 2.6608490845e-02f },
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{ 9.7758004319e-18f, 5.3216978908e-02f }, { 2.0521502845e-01f, -2.0521502845e-01f },
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{ 5.7008099556e-01f, -1.3962957329e-16f }, { 2.0521502845e-01f, 2.0521502845e-01f },
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{ -1.6293000720e-17f, -5.3216978908e-02f }, { 2.6608490845e-02f, -2.6608490845e-02f },
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{ -2.1286793053e-02f, 7.8206408930e-18f }, { 5.3216978397e-03f, 5.3216978397e-03f },
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{ -6.5172004590e-19f, -1.5204851516e-03f }, { 3.8012127427e-03f, -3.8012127427e-03f },
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} };
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constexpr std::array<std::complex<float>, 32> rrc_taps_32_p { {
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{ -1.2495006667e-03f, 0.0000000000e+00f }, { 7.5862532786e-04f, 7.5862532786e-04f },
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{ 7.1465238505e-21f, 1.1671159155e-04f }, { 8.7533694842e-04f, -8.7533694842e-04f },
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{ -2.2281305864e-03f, 2.7286729908e-19f }, { 1.4482847468e-03f, 1.4482847468e-03f },
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{ 5.9121245638e-20f, 3.2184107113e-04f }, { 1.7701258199e-03f, -1.7701258199e-03f },
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{ -5.0575020723e-03f, 1.2387307449e-18f }, { 3.7931268039e-03f, 3.7931268039e-03f },
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{ 4.6452407924e-19f, 1.5172507847e-03f }, { 5.3103774596e-03f, -5.3103774596e-03f },
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{ -2.1241510287e-02f, 7.8040042746e-18f }, { 2.6551890262e-02f, 2.6551890262e-02f },
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{ 2.2761678735e-17f, 5.3103774786e-02f }, { 2.0477849246e-01f, -2.0477849246e-01f },
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{ 5.6886833906e-01f, -2.7866511623e-16f }, { 2.0477849246e-01f, 2.0477849246e-01f },
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{ -2.9265015516e-17f, -5.3103774786e-02f }, { 2.6551890262e-02f, -2.6551890262e-02f },
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{ -2.1241510287e-02f, 1.3006673791e-17f }, { 5.3103774596e-03f, 5.3103774596e-03f },
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{ -3.7171317828e-18f, -1.5172507847e-03f }, { 3.7931268039e-03f, -3.7931268039e-03f },
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{ -5.0575020723e-03f, 3.7161922347e-18f }, { 1.7701258199e-03f, 1.7701258199e-03f },
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{ 3.1551252346e-19f, -3.2184107113e-04f }, { 1.4482847468e-03f, -1.4482847468e-03f },
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{ -2.2281305864e-03f, 1.9100710935e-18f }, { 8.7533694842e-04f, 8.7533694842e-04f },
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{ -3.1451929164e-19f, -1.1671159155e-04f }, { 7.5862532786e-04f, -7.5862532786e-04f },
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} };
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struct BitRemap {
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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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struct CRCBitRemap {
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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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using FieldReader = baseband::FieldReader<std::bitset<1024>, BitRemap>;
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using CRCFieldReader = baseband::FieldReader<std::bitset<1024>, CRCBitRemap>;
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struct PacketLengthRange {
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constexpr PacketLengthRange(
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) : min_bytes { 0 },
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max_bytes { 0 }
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{
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}
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constexpr PacketLengthRange(
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const uint16_t min_bits,
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const uint16_t max_bits
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) : min_bytes { static_cast<uint8_t>(min_bits / 8U) },
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max_bytes { static_cast<uint8_t>(max_bits / 8U) }
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{
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// static_assert((min_bits & 7) == 0, "minimum bits not a multiple of 8");
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// static_assert((max_bits & 7) == 0, "minimum bits not a multiple of 8");
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}
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bool contains(const size_t bit_count) const {
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return !is_above(bit_count) && !is_below(bit_count);
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}
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bool is_above(const size_t bit_count) const {
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return (min() > bit_count);
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}
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bool is_below(const size_t bit_count) const {
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return (max() < bit_count);
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}
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size_t min() const {
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return min_bytes * 8;
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}
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size_t max() const {
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return max_bytes * 8;
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}
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private:
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const uint8_t min_bytes;
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const uint8_t max_bytes;
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};
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constexpr std::array<PacketLengthRange, 64> packet_length_range { {
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{ 0, 0 }, // 0
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{ 168, 168 }, // 1
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{ 168, 168 }, // 2
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{ 168, 168 }, // 3
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{ 168, 168 }, // 4
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{ 424, 424 }, // 5
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{ 0, 0 }, // 6
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{ 0, 0 }, // 7
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{ 0, 1008 }, // 8
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{ 0, 0 }, // 9
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{ 0, 0 }, // 10
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{ 0, 0 }, // 11
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{ 0, 0 }, // 12
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{ 0, 0 }, // 13
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{ 0, 0 }, // 14
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{ 0, 0 }, // 15
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{ 0, 0 }, // 16
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{ 0, 0 }, // 17
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{ 168, 168 }, // 18
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{ 0, 0 }, // 19
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{ 72, 160 }, // 20
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{ 272, 360 }, // 21
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{ 168, 168 }, // 22
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{ 160, 160 }, // 23
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{ 160, 168 }, // 24
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{ 0, 168 }, // 25
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{ 0, 0 }, // 26
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{ 0, 0 }, // 27
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{ 0, 0 }, // 28
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{ 0, 0 }, // 29
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{ 0, 0 }, // 30
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{ 0, 0 }, // 31
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} };
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struct PacketLengthValidator {
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bool operator()(const uint_fast8_t message_id, const size_t length) {
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return packet_length_range[message_id].contains(length);
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}
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};
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struct PacketTooLong {
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bool operator()(const uint_fast8_t message_id, const size_t length) {
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return packet_length_range[message_id].is_below(length);
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}
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};
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struct CRCCheck {
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bool operator()(const std::bitset<1024>& payload, const size_t data_length) {
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CRCFieldReader field_crc { payload };
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CRC<uint16_t> ais_fcs { 0x1021 };
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uint16_t crc_calculated = 0xffff;
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for(size_t i=0; i<data_length + 16; i+=8) {
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if( i == data_length ) {
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crc_calculated ^= 0xffff;
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}
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const uint8_t byte = field_crc.read(i, 8);
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crc_calculated = ais_fcs.calculate_byte(crc_calculated, byte);
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}
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return crc_calculated == 0x0000;
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}
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};
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} /* namespace ais */
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} /* namespace baseband */
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#endif/*__BASEBAND_AIS_H__*/
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