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36
37#ifndef QMODBUSADU_P_H
38#define QMODBUSADU_P_H
39
40#include <QtSerialBus/qmodbuspdu.h>
41
42//
43// W A R N I N G
44// -------------
45//
46// This file is not part of the Qt API. It exists purely as an
47// implementation detail. This header file may change from version to
48// version without notice, or even be removed.
49//
50// We mean it.
51//
52
53QT_BEGIN_NAMESPACE
54
55class QModbusSerialAdu
56{
57public:
58 enum Type {
59 Ascii,
60 Rtu
61 };
62
63 inline QModbusSerialAdu(Type type, const QByteArray &data)
64 : m_type(type), m_data(data), m_rawData(data)
65 {
66 if (m_type == Ascii)
67 m_data = QByteArray::fromHex(hexEncoded: m_data.mid(index: 1, len: m_data.size() - 3));
68 }
69
70 inline int size() const {
71 if (m_type == Ascii)
72 return m_data.size() - 1; // one byte, LRC
73 return m_data.size() - 2; // two bytes, CRC
74 }
75 inline QByteArray data() const { return m_data.left(len: size()); }
76
77 inline int rawSize() const { return m_rawData.size(); }
78 inline QByteArray rawData() const { return m_rawData; }
79
80 inline int serverAddress() const {
81 Q_ASSERT_X(!m_data.isEmpty(), "QModbusAdu::serverAddress()", "Empty ADU.");
82 return quint8(m_data.at(i: 0));
83 }
84
85 inline QModbusPdu pdu() const {
86 Q_ASSERT_X(!m_data.isEmpty(), "QModbusAdu::pdu()", "Empty ADU.");
87 return QModbusPdu(QModbusPdu::FunctionCode(m_data.at(i: 1)), m_data.mid(index: 2, len: size() - 2));
88 }
89
90 template <typename T>
91 auto checksum() const -> decltype(T()) {
92 Q_ASSERT_X(!m_data.isEmpty(), "QModbusAdu::checksum()", "Empty ADU.");
93 if (m_type == Ascii)
94 return quint8(m_data[m_data.size() - 1]);
95 return quint16(quint8(m_data[m_data.size() - 2]) << 8 | quint8(m_data[m_data.size() - 1]));
96 }
97
98 inline bool matchingChecksum() const {
99 Q_ASSERT_X(!m_data.isEmpty(), "QModbusAdu::matchingChecksum()", "Empty ADU.");
100 if (m_type == Ascii)
101 return QModbusSerialAdu::calculateLRC(data: data(), len: size()) == checksum<quint8>();
102 return QModbusSerialAdu::calculateCRC(data: data(), len: size()) == checksum<quint16>();
103 }
104
105 /*!
106 \internal
107 \fn quint8 QModbusSerialAdu::calculateLRC(const char *data, qint32 len)
108
109 Returns the LRC checksum of the first \a len bytes of \a data. The checksum is independent
110 of the byte order (endianness).
111 */
112 inline static quint8 calculateLRC(const char *data, qint32 len)
113 {
114 quint32 lrc = 0;
115 while (len--)
116 lrc += *data++;
117 return -(quint8(lrc));
118 }
119
120 /*!
121 \internal
122 \fn quint16 QModbusSerialAdu::calculateCRC(const char *data, qint32 len) const
123
124 Returns the CRC checksum of the first \a len bytes of \a data.
125
126 \note The code used by the function was generated with pycrc. There is no copyright assigned
127 to the generated code, however, the author of the script requests to show the line stating
128 that the code was generated by pycrc (see implementation).
129 */
130 inline static quint16 calculateCRC(const char *data, qint32 len)
131 {
132 // Generated by pycrc v0.8.3, https://pycrc.org
133 // Width = 16, Poly = 0x8005, XorIn = 0xffff, ReflectIn = True,
134 // XorOut = 0x0000, ReflectOut = True, Algorithm = bit-by-bit-fast
135
136 quint16 crc = 0xFFFF;
137 while (len--) {
138 const quint8 c = *data++;
139 for (qint32 i = 0x01; i & 0xFF; i <<= 1) {
140 bool bit = crc & 0x8000;
141 if (c & i)
142 bit = !bit;
143 crc <<= 1;
144 if (bit)
145 crc ^= 0x8005;
146 }
147 crc &= 0xFFFF;
148 }
149 crc = crc_reflect(data: crc & 0xFFFF, len: 16) ^ 0x0000;
150 return (crc >> 8) | (crc << 8); // swap bytes
151 }
152
153 inline static QByteArray create(Type type, int serverAddress, const QModbusPdu &pdu,
154 char delimiter = '\n') {
155 QByteArray result;
156 QDataStream out(&result, QIODevice::WriteOnly);
157 out << quint8(serverAddress) << pdu;
158
159 if (type == Ascii) {
160 out << calculateLRC(data: result, len: result.size());
161 return ":" + result.toHex() + "\r" + delimiter;
162 } else {
163 out << calculateCRC(data: result, len: result.size());
164 }
165 return result;
166 }
167
168private:
169 inline static quint16 crc_reflect(quint16 data, qint32 len)
170 {
171 // Generated by pycrc v0.8.3, https://pycrc.org
172 // Width = 16, Poly = 0x8005, XorIn = 0xffff, ReflectIn = True,
173 // XorOut = 0x0000, ReflectOut = True, Algorithm = bit-by-bit-fast
174
175 quint16 ret = data & 0x01;
176 for (qint32 i = 1; i < len; i++) {
177 data >>= 1;
178 ret = (ret << 1) | (data & 0x01);
179 }
180 return ret;
181 }
182
183private:
184 Type m_type = Rtu;
185 QByteArray m_data;
186 QByteArray m_rawData;
187};
188
189QT_END_NAMESPACE
190
191#endif // QMODBUSADU_P_H
192

source code of qtserialbus/src/serialbus/qmodbusadu_p.h