mirror of
https://github.com/eried/portapack-mayhem.git
synced 2025-01-13 00:09:43 -05:00
281 lines
9.0 KiB
C++
281 lines
9.0 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_n { {
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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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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_n { {
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{ 0.02104694f, 0.00000000f }, { -0.02630867f, -0.02630867f },
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{ 0.00000000f, -0.05261734f }, { -0.20290270f, 0.20290270f },
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{ -0.56365746f, 0.00000000f }, { -0.20290270f, -0.20290270f },
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{ 0.00000000f, 0.05261734f }, { -0.02630867f, 0.02630867f },
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} };
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constexpr std::array<std::complex<float>, 8> rrc_taps_8_p { {
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{ 0.02104694f, 0.00000000f }, { -0.02630867f, 0.02630867f },
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{ 0.00000000f, 0.05261734f }, { -0.20290270f, -0.20290270f },
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{ -0.56365746f, 0.00000000f }, { -0.20290270f, 0.20290270f },
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{ 0.00000000f, -0.05261734f }, { -0.02630867f, -0.02630867f },
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} };
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constexpr std::array<std::complex<float>, 16> rrc_taps_16_n { {
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{ -0.00506828f, 0.00000000f }, { 0.00380121f, 0.00380121f },
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{ 0.00000000f, 0.00152049f }, { 0.00532170f, -0.00532170f },
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{ -0.02128679f, 0.00000000f }, { 0.02660849f, 0.02660849f },
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{ 0.00000000f, 0.05321698f }, { 0.20521503f, -0.20521503f },
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{ 0.57008100f, -0.00000000f }, { 0.20521503f, 0.20521503f },
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{ -0.00000000f, -0.05321698f }, { 0.02660849f, -0.02660849f },
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{ -0.02128679f, 0.00000000f }, { 0.00532170f, 0.00532170f },
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{ -0.00000000f, -0.00152049f }, { 0.00380121f, -0.00380121f },
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} };
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constexpr std::array<std::complex<float>, 16> rrc_taps_16_p { {
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{ -0.00506828f, 0.00000000f }, { 0.00380121f, -0.00380121f },
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{ 0.00000000f, -0.00152049f }, { 0.00532170f, 0.00532170f },
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{ -0.02128679f, -0.00000000f }, { 0.02660849f, -0.02660849f },
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{ 0.00000000f, -0.05321698f }, { 0.20521503f, 0.20521503f },
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{ 0.57008100f, 0.00000000f }, { 0.20521503f, -0.20521503f },
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{ -0.00000000f, 0.05321698f }, { 0.02660849f, 0.02660849f },
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{ -0.02128679f, -0.00000000f }, { 0.00532170f, -0.00532170f },
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{ -0.00000000f, 0.00152049f }, { 0.00380121f, 0.00380121f },
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} };
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constexpr std::array<std::complex<float>, 32> rrc_taps_32_n { {
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{ -0.00124950f, 0.00000000f }, { 0.00075863f, 0.00075863f },
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{ 0.00000000f, 0.00011671f }, { 0.00087534f, -0.00087534f },
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{ -0.00222813f, 0.00000000f }, { 0.00144828f, 0.00144828f },
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{ 0.00000000f, 0.00032184f }, { 0.00177013f, -0.00177013f },
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{ -0.00505750f, 0.00000000f }, { 0.00379313f, 0.00379313f },
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{ 0.00000000f, 0.00151725f }, { 0.00531038f, -0.00531038f },
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{ -0.02124151f, 0.00000000f }, { 0.02655189f, 0.02655189f },
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{ 0.00000000f, 0.05310377f }, { 0.20477849f, -0.20477849f },
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{ 0.56886834f, -0.00000000f }, { 0.20477849f, 0.20477849f },
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{ -0.00000000f, -0.05310377f }, { 0.02655189f, -0.02655189f },
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{ -0.02124151f, 0.00000000f }, { 0.00531038f, 0.00531038f },
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{ -0.00000000f, -0.00151725f }, { 0.00379313f, -0.00379313f },
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{ -0.00505750f, 0.00000000f }, { 0.00177013f, 0.00177013f },
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{ 0.00000000f, -0.00032184f }, { 0.00144828f, -0.00144828f },
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{ -0.00222813f, 0.00000000f }, { 0.00087534f, 0.00087534f },
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{ -0.00000000f, -0.00011671f }, { 0.00075863f, -0.00075863f },
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} };
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constexpr std::array<std::complex<float>, 32> rrc_taps_32_p { {
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{ -0.00124950f, 0.00000000f }, { 0.00075863f, -0.00075863f },
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{ 0.00000000f, -0.00011671f }, { 0.00087534f, 0.00087534f },
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{ -0.00222813f, -0.00000000f }, { 0.00144828f, -0.00144828f },
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{ 0.00000000f, -0.00032184f }, { 0.00177013f, 0.00177013f },
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{ -0.00505750f, -0.00000000f }, { 0.00379313f, -0.00379313f },
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{ 0.00000000f, -0.00151725f }, { 0.00531038f, 0.00531038f },
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{ -0.02124151f, -0.00000000f }, { 0.02655189f, -0.02655189f },
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{ 0.00000000f, -0.05310377f }, { 0.20477849f, 0.20477849f },
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{ 0.56886834f, 0.00000000f }, { 0.20477849f, -0.20477849f },
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{ -0.00000000f, 0.05310377f }, { 0.02655189f, 0.02655189f },
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{ -0.02124151f, -0.00000000f }, { 0.00531038f, -0.00531038f },
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{ -0.00000000f, 0.00151725f }, { 0.00379313f, 0.00379313f },
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{ -0.00505750f, -0.00000000f }, { 0.00177013f, -0.00177013f },
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{ 0.00000000f, 0.00032184f }, { 0.00144828f, 0.00144828f },
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{ -0.00222813f, -0.00000000f }, { 0.00087534f, -0.00087534f },
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{ -0.00000000f, 0.00011671f }, { 0.00075863f, 0.00075863f },
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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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