2015-11-06 21:53:04 +00:00
|
|
|
/*
|
|
|
|
* Copyright (C) 2015 Jared Boone, ShareBrained Technology, Inc.
|
|
|
|
*
|
|
|
|
* This file is part of PortaPack.
|
|
|
|
*
|
|
|
|
* This program is free software; you can redistribute it and/or modify
|
|
|
|
* it under the terms of the GNU General Public License as published by
|
|
|
|
* the Free Software Foundation; either version 2, or (at your option)
|
|
|
|
* any later version.
|
|
|
|
*
|
|
|
|
* This program is distributed in the hope that it will be useful,
|
|
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
|
|
* GNU General Public License for more details.
|
|
|
|
*
|
|
|
|
* You should have received a copy of the GNU General Public License
|
|
|
|
* along with this program; see the file COPYING. If not, write to
|
|
|
|
* the Free Software Foundation, Inc., 51 Franklin Street,
|
|
|
|
* Boston, MA 02110-1301, USA.
|
|
|
|
*/
|
|
|
|
|
|
|
|
#include "ais_baseband.hpp"
|
|
|
|
|
|
|
|
#include <cstdint>
|
|
|
|
#include <cstddef>
|
|
|
|
#include <cstdlib>
|
|
|
|
#include <string>
|
|
|
|
|
|
|
|
#include "crc.hpp"
|
|
|
|
|
|
|
|
// TODO: Move string formatting elsewhere!!!
|
|
|
|
#include "ui_widget.hpp"
|
|
|
|
|
|
|
|
namespace baseband {
|
|
|
|
|
|
|
|
template<typename T, typename BitRemap>
|
|
|
|
class FieldReader {
|
|
|
|
public:
|
|
|
|
constexpr FieldReader(
|
|
|
|
const T& data
|
|
|
|
) : data { data }
|
|
|
|
{
|
|
|
|
}
|
|
|
|
|
|
|
|
uint32_t read(const size_t start_bit, const size_t length) const {
|
|
|
|
uint32_t value = 0;
|
|
|
|
for(size_t i=start_bit; i<(start_bit + length); i++) {
|
|
|
|
value = (value << 1) | data[bit_remap(i)];
|
|
|
|
}
|
|
|
|
return value;
|
|
|
|
}
|
|
|
|
|
|
|
|
private:
|
|
|
|
const T& data;
|
|
|
|
const BitRemap bit_remap { };
|
|
|
|
};
|
|
|
|
|
|
|
|
namespace ais {
|
|
|
|
|
|
|
|
struct BitRemap {
|
|
|
|
size_t operator()(const size_t bit_index) const {
|
|
|
|
return bit_index ^ 7;
|
|
|
|
}
|
|
|
|
};
|
|
|
|
|
|
|
|
struct CRCBitRemap {
|
|
|
|
size_t operator()(const size_t bit_index) const {
|
|
|
|
return bit_index;
|
|
|
|
}
|
|
|
|
};
|
|
|
|
|
|
|
|
using FieldReader = baseband::FieldReader<std::bitset<1024>, BitRemap>;
|
|
|
|
using CRCFieldReader = baseband::FieldReader<std::bitset<1024>, CRCBitRemap>;
|
|
|
|
|
|
|
|
struct PacketLengthRange {
|
|
|
|
constexpr PacketLengthRange(
|
|
|
|
) : min_bytes { 0 },
|
|
|
|
max_bytes { 0 }
|
|
|
|
{
|
|
|
|
}
|
|
|
|
|
|
|
|
constexpr PacketLengthRange(
|
|
|
|
const uint16_t min_bits,
|
|
|
|
const uint16_t max_bits
|
|
|
|
) : min_bytes { static_cast<uint8_t>(min_bits / 8U) },
|
|
|
|
max_bytes { static_cast<uint8_t>(max_bits / 8U) }
|
|
|
|
{
|
|
|
|
// static_assert((min_bits & 7) == 0, "minimum bits not a multiple of 8");
|
|
|
|
// static_assert((max_bits & 7) == 0, "minimum bits not a multiple of 8");
|
|
|
|
}
|
|
|
|
|
|
|
|
bool contains(const size_t bit_count) const {
|
|
|
|
return !is_above(bit_count) && !is_below(bit_count);
|
|
|
|
}
|
|
|
|
|
|
|
|
bool is_above(const size_t bit_count) const {
|
|
|
|
return (min() > bit_count);
|
|
|
|
}
|
|
|
|
|
|
|
|
bool is_below(const size_t bit_count) const {
|
|
|
|
return (max() < bit_count);
|
|
|
|
}
|
|
|
|
|
|
|
|
size_t min() const {
|
|
|
|
return min_bytes * 8;
|
|
|
|
}
|
|
|
|
|
|
|
|
size_t max() const {
|
|
|
|
return max_bytes * 8;
|
|
|
|
}
|
|
|
|
|
|
|
|
private:
|
|
|
|
const uint8_t min_bytes;
|
|
|
|
const uint8_t max_bytes;
|
|
|
|
};
|
|
|
|
|
|
|
|
static constexpr std::array<PacketLengthRange, 64> packet_length_range { {
|
|
|
|
{ 0, 0 }, // 0
|
|
|
|
{ 168, 168 }, // 1
|
|
|
|
{ 168, 168 }, // 2
|
|
|
|
{ 168, 168 }, // 3
|
|
|
|
{ 168, 168 }, // 4
|
|
|
|
{ 424, 424 }, // 5
|
|
|
|
{ 0, 0 }, // 6
|
|
|
|
{ 0, 0 }, // 7
|
|
|
|
{ 0, 1008 }, // 8
|
|
|
|
{ 0, 0 }, // 9
|
|
|
|
{ 0, 0 }, // 10
|
|
|
|
{ 0, 0 }, // 11
|
|
|
|
{ 0, 0 }, // 12
|
|
|
|
{ 0, 0 }, // 13
|
|
|
|
{ 0, 0 }, // 14
|
|
|
|
{ 0, 0 }, // 15
|
|
|
|
{ 0, 0 }, // 16
|
|
|
|
{ 0, 0 }, // 17
|
|
|
|
{ 168, 168 }, // 18
|
|
|
|
{ 0, 0 }, // 19
|
|
|
|
{ 72, 160 }, // 20
|
|
|
|
{ 272, 360 }, // 21
|
|
|
|
{ 168, 168 }, // 22
|
|
|
|
{ 160, 160 }, // 23
|
|
|
|
{ 160, 168 }, // 24
|
|
|
|
{ 0, 168 }, // 25
|
|
|
|
{ 0, 0 }, // 26
|
|
|
|
{ 0, 0 }, // 27
|
|
|
|
{ 0, 0 }, // 28
|
|
|
|
{ 0, 0 }, // 29
|
|
|
|
{ 0, 0 }, // 30
|
|
|
|
{ 0, 0 }, // 31
|
|
|
|
} };
|
|
|
|
|
|
|
|
struct PacketLengthValidator {
|
|
|
|
bool operator()(const uint_fast8_t message_id, const size_t length) {
|
|
|
|
return packet_length_range[message_id].contains(length);
|
|
|
|
}
|
|
|
|
};
|
|
|
|
|
|
|
|
struct PacketTooLong {
|
|
|
|
bool operator()(const uint_fast8_t message_id, const size_t length) {
|
|
|
|
return packet_length_range[message_id].is_below(length);
|
|
|
|
}
|
|
|
|
};
|
|
|
|
|
|
|
|
struct CRCCheck {
|
|
|
|
bool operator()(const std::bitset<1024>& payload, const size_t data_length) {
|
|
|
|
CRCFieldReader field_crc { payload };
|
|
|
|
CRC<uint16_t> ais_fcs { 0x1021 };
|
|
|
|
|
|
|
|
uint16_t crc_calculated = 0xffff;
|
|
|
|
|
|
|
|
for(size_t i=0; i<data_length + 16; i+=8) {
|
|
|
|
if( i == data_length ) {
|
|
|
|
crc_calculated ^= 0xffff;
|
|
|
|
}
|
|
|
|
const uint8_t byte = field_crc.read(i, 8);
|
|
|
|
crc_calculated = ais_fcs.calculate_byte(crc_calculated, byte);
|
|
|
|
}
|
|
|
|
|
|
|
|
return crc_calculated == 0x0000;
|
|
|
|
}
|
|
|
|
};
|
|
|
|
|
|
|
|
static int32_t ais_latitude_normalized(
|
|
|
|
const FieldReader& field,
|
|
|
|
const size_t start_bit
|
|
|
|
) {
|
|
|
|
// Shifting and dividing is to sign-extend the source field.
|
|
|
|
// TODO: There's probably a more elegant way to do it.
|
|
|
|
return static_cast<int32_t>(field.read(start_bit, 27) << 5) / 32;
|
|
|
|
}
|
|
|
|
|
|
|
|
static int32_t ais_longitude_normalized(
|
|
|
|
const FieldReader& field,
|
|
|
|
const size_t start_bit
|
|
|
|
) {
|
|
|
|
// Shifting and dividing is to sign-extend the source field.
|
|
|
|
// TODO: There's probably a more elegant way to do it.
|
|
|
|
return static_cast<int32_t>(field.read(start_bit, 28) << 4) / 16;
|
|
|
|
}
|
|
|
|
|
|
|
|
static std::string ais_format_latlon_normalized(const int32_t normalized) {
|
|
|
|
const int32_t t = (normalized * 5) / 3;
|
|
|
|
const int32_t degrees = t / (100 * 10000);
|
|
|
|
const int32_t fraction = std::abs(t) % (100 * 10000);
|
|
|
|
return ui::to_string_dec_int(degrees) + "." + ui::to_string_dec_int(fraction, 6, '0');
|
|
|
|
}
|
|
|
|
|
|
|
|
static std::string ais_format_latitude(
|
|
|
|
const FieldReader& field,
|
|
|
|
const size_t start_bit
|
|
|
|
) {
|
|
|
|
const auto value = static_cast<int32_t>(field.read(start_bit, 27) << 5) / 32;
|
|
|
|
return ais_format_latlon_normalized(value);
|
|
|
|
}
|
|
|
|
|
|
|
|
static std::string ais_format_longitude(
|
|
|
|
const FieldReader& field,
|
|
|
|
const size_t start_bit
|
|
|
|
) {
|
|
|
|
const auto value = static_cast<int32_t>(field.read(start_bit, 28) << 4) / 16;
|
|
|
|
return ais_format_latlon_normalized(value);
|
|
|
|
}
|
|
|
|
|
|
|
|
struct ais_datetime {
|
|
|
|
uint16_t year;
|
|
|
|
uint8_t month;
|
|
|
|
uint8_t day;
|
|
|
|
uint8_t hour;
|
|
|
|
uint8_t minute;
|
|
|
|
uint8_t second;
|
|
|
|
};
|
|
|
|
|
|
|
|
static ais_datetime ais_get_datetime(
|
|
|
|
const FieldReader& field,
|
|
|
|
const size_t start_bit
|
|
|
|
) {
|
|
|
|
return {
|
|
|
|
static_cast<uint16_t>(field.read(start_bit + 0, 14)),
|
|
|
|
static_cast<uint8_t >(field.read(start_bit + 14, 4)),
|
|
|
|
static_cast<uint8_t >(field.read(start_bit + 18, 5)),
|
|
|
|
static_cast<uint8_t >(field.read(start_bit + 23, 5)),
|
|
|
|
static_cast<uint8_t >(field.read(start_bit + 28, 6)),
|
|
|
|
static_cast<uint8_t >(field.read(start_bit + 34, 6)),
|
|
|
|
};
|
|
|
|
}
|
|
|
|
|
|
|
|
static std::string ais_format_datetime(
|
|
|
|
const FieldReader& field,
|
|
|
|
const size_t start_bit
|
|
|
|
) {
|
|
|
|
const auto datetime = ais_get_datetime(field, start_bit);
|
|
|
|
return ui::to_string_dec_uint(datetime.year, 4) + "/" +
|
|
|
|
ui::to_string_dec_uint(datetime.month, 2, '0') + "/" +
|
|
|
|
ui::to_string_dec_uint(datetime.day, 2, '0') + " " +
|
|
|
|
ui::to_string_dec_uint(datetime.hour, 2, '0') + ":" +
|
|
|
|
ui::to_string_dec_uint(datetime.minute, 2, '0') + ":" +
|
|
|
|
ui::to_string_dec_uint(datetime.second, 2, '0');
|
|
|
|
}
|
|
|
|
|
|
|
|
static char ais_char_to_ascii(const uint8_t c) {
|
|
|
|
return (c ^ 32) + 32;
|
|
|
|
}
|
|
|
|
|
|
|
|
static std::string ais_read_text(
|
|
|
|
const FieldReader& field,
|
|
|
|
const size_t start_bit,
|
|
|
|
const size_t character_count
|
|
|
|
) {
|
|
|
|
std::string result;
|
|
|
|
const size_t character_length = 6;
|
|
|
|
const size_t end_bit = start_bit + character_count * character_length;
|
|
|
|
for(size_t i=start_bit; i<end_bit; i+=character_length) {
|
|
|
|
result += ais_char_to_ascii(field.read(i, character_length));
|
|
|
|
}
|
|
|
|
|
|
|
|
return result;
|
|
|
|
}
|
|
|
|
|
|
|
|
static std::string ais_format_navigational_status(const unsigned int value) {
|
|
|
|
switch(value) {
|
|
|
|
case 0: return "under way w/engine";
|
|
|
|
case 1: return "at anchor";
|
|
|
|
case 2: return "not under command";
|
|
|
|
case 3: return "restricted maneuv";
|
|
|
|
case 4: return "constrained draught";
|
|
|
|
case 5: return "moored";
|
|
|
|
case 6: return "aground";
|
|
|
|
case 7: return "fishing";
|
|
|
|
case 8: return "sailing";
|
|
|
|
case 9: case 10: case 13: return "reserved";
|
|
|
|
case 11: return "towing astern";
|
|
|
|
case 12: return "towing ahead/along";
|
|
|
|
case 14: return "SART/MOB/EPIRB";
|
|
|
|
case 15: return "undefined";
|
|
|
|
default: return "unexpected";
|
|
|
|
}
|
|
|
|
}
|
|
|
|
|
2015-11-09 22:35:06 +00:00
|
|
|
decoded_packet packet_decode(const std::bitset<1024>& payload, const size_t payload_length) {
|
|
|
|
// TODO: Unstuff here, not in baseband!
|
|
|
|
|
2015-11-09 22:38:09 +00:00
|
|
|
// Subtract end flag (6 bits) + one unstuffing bit (occurs during end flag).
|
|
|
|
const size_t data_and_fcs_length = payload_length - 7;
|
2015-11-09 22:35:06 +00:00
|
|
|
|
|
|
|
if( data_and_fcs_length < 38 ) {
|
|
|
|
return { "short " + ui::to_string_dec_uint(data_and_fcs_length, 3), "" };
|
2015-11-06 21:53:04 +00:00
|
|
|
}
|
|
|
|
|
2015-11-09 22:35:06 +00:00
|
|
|
const size_t extra_bits = data_and_fcs_length & 7;
|
2015-11-06 21:53:04 +00:00
|
|
|
if( extra_bits != 0 ) {
|
2015-11-09 22:35:06 +00:00
|
|
|
return { "extra bits " + ui::to_string_dec_uint(data_and_fcs_length, 3), "" };
|
2015-11-06 21:53:04 +00:00
|
|
|
}
|
|
|
|
|
2015-11-09 22:35:06 +00:00
|
|
|
FieldReader field { payload };
|
2015-11-06 21:53:04 +00:00
|
|
|
|
|
|
|
const auto message_id = field.read(0, 6);
|
|
|
|
|
2015-11-09 22:35:06 +00:00
|
|
|
const size_t data_length = data_and_fcs_length - 16;
|
2015-11-06 21:53:04 +00:00
|
|
|
PacketLengthValidator packet_length_valid;
|
2015-11-09 22:35:06 +00:00
|
|
|
if( !packet_length_valid(message_id, data_length) ) {
|
|
|
|
return { "bad length " + ui::to_string_dec_uint(data_length, 3), "" };
|
2015-11-06 21:53:04 +00:00
|
|
|
}
|
|
|
|
|
|
|
|
CRCCheck crc_ok;
|
2015-11-09 22:35:06 +00:00
|
|
|
if( !crc_ok(payload, data_length) ) {
|
2015-11-06 21:53:04 +00:00
|
|
|
return { "crc", "" };
|
|
|
|
}
|
|
|
|
|
|
|
|
const auto source_id = field.read(8, 30);
|
|
|
|
std::string result { ui::to_string_dec_uint(message_id, 2) + " " + ui::to_string_dec_uint(source_id, 10) };
|
|
|
|
|
|
|
|
switch(message_id) {
|
|
|
|
case 1:
|
|
|
|
case 2:
|
|
|
|
case 3:
|
|
|
|
{
|
|
|
|
const auto navigational_status = field.read(38, 4);
|
|
|
|
result += " " + ais_format_navigational_status(navigational_status);
|
|
|
|
result += " " + ais_format_latlon_normalized(ais_latitude_normalized(field, 89));
|
|
|
|
result += " " + ais_format_latlon_normalized(ais_longitude_normalized(field, 61));
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
|
|
|
|
case 4:
|
|
|
|
{
|
|
|
|
result += " " + ais_format_datetime(field, 38);
|
|
|
|
result += " " + ais_format_latlon_normalized(ais_latitude_normalized(field, 107));
|
|
|
|
result += " " + ais_format_latlon_normalized(ais_longitude_normalized(field, 79));
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
|
|
|
|
case 5:
|
|
|
|
{
|
|
|
|
const auto call_sign = ais_read_text(field, 70, 7);
|
|
|
|
const auto name = ais_read_text(field, 112, 20);
|
|
|
|
const auto destination = ais_read_text(field, 302, 20);
|
|
|
|
result += " \"" + call_sign + "\" \"" + name + "\" \"" + destination + "\"";
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
|
|
|
|
case 21:
|
|
|
|
{
|
|
|
|
const auto name = ais_read_text(field, 43, 20);
|
|
|
|
result += " \"" + name + "\" " + ais_format_latitude(field, 192) + " " + ais_format_longitude(field, 164);
|
|
|
|
}
|
|
|
|
break;
|
|
|
|
|
|
|
|
default:
|
|
|
|
break;
|
|
|
|
}
|
|
|
|
|
|
|
|
return { "OK", result };
|
|
|
|
}
|
|
|
|
|
|
|
|
} /* namespace ais */
|
|
|
|
} /* namespace baseband */
|