mirror of
https://github.com/f4exb/sdrangel.git
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149 lines
4.0 KiB
C++
149 lines
4.0 KiB
C++
///////////////////////////////////////////////////////////////////////////////////
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// Copyright (C) 2022 Edouard Griffiths, F4EXB //
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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 as version 3 of the License, or //
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// (at your option) 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 V3 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. If not, see <http://www.gnu.org/licenses/>. //
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///////////////////////////////////////////////////////////////////////////////////
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#include <QString>
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#include <array>
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#include "util/crc.h"
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#include "m17modax25.h"
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M17ModAX25::M17ModAX25() :
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m_ax25Control(3),
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m_ax25PID(AX25_NO_L3)
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{}
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M17ModAX25::~M17ModAX25()
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{}
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QByteArray M17ModAX25::makePacket(const QString& callsign, const QString& to, const QString& via, const QString& data)
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{
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std::array<uint8_t, AX25_MAX_BYTES> packet;
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uint8_t *crc_start;
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uint8_t *p;
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crc16x25 crc;
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uint16_t crcValue;
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int len;
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int packet_length;
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// Create AX.25 packet
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p = packet.data();
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// Unique preamble flag
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// *p++ = AX25_FLAG;
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crc_start = p;
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// Dest
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p = ax25_address(p, to, 0xe0);
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// From
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p = ax25_address(p, callsign, 0x60);
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// Via
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p = ax25_address(p, via, 0x61);
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// Control
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*p++ = m_ax25Control;
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// PID
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*p++ = m_ax25PID;
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// Data
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len = data.length();
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memcpy(p, data.toUtf8(), len);
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p += len;
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// CRC (do not include flags)
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crc.calculate(crc_start, p-crc_start);
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crcValue = crc.get();
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*p++ = crcValue & 0xff;
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*p++ = (crcValue >> 8);
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// Unique postamble flag
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// *p++ = AX25_FLAG;
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packet_length = p-&packet[0];
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return QByteArray(reinterpret_cast<const char*>(packet.data()), packet_length);
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}
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uint8_t *M17ModAX25::ax25_address(uint8_t *p, QString address, uint8_t crrl)
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{
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int len;
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int i;
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QByteArray b;
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uint8_t ssid = 0;
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bool hyphenSeen = false;
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len = address.length();
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b = address.toUtf8();
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ssid = 0;
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for (i = 0; i < 6; i++)
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{
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if ((i < len) && !hyphenSeen)
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{
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if (b[i] == '-')
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{
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ax25_ssid(b, i, len, ssid);
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hyphenSeen = true;
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*p++ = ' ' << 1;
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}
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else
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{
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*p++ = b[i] << 1;
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}
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}
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else
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{
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*p++ = ' ' << 1;
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}
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}
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if (b[i] == '-') {
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ax25_ssid(b, i, len, ssid);
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}
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*p++ = crrl | (ssid << 1);
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return p;
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}
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bool M17ModAX25::ax25_ssid(QByteArray& b, int i, int len, uint8_t& ssid)
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{
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if (b[i] == '-')
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{
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if (len > i + 1)
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{
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ssid = b[i+1] - '0';
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if ((len > i + 2) && isdigit(b[i+2])) {
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ssid = (ssid*10) + (b[i+2] - '0');
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}
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if (ssid >= 16)
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{
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qDebug("M17ModAX25::ax25_ssid: ax25_address: SSID greater than 15 not supported");
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ssid = ssid & 0xf;
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return false;
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}
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else
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{
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return true;
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}
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}
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else
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{
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qDebug("M17ModAX25::ax25_ssid: ax25_address: SSID number missing");
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return false;
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}
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}
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else
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{
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return false;
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}
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}
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