43 lines
1.2 KiB
C++
43 lines
1.2 KiB
C++
#include "crc.h"
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// 函数声明
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// void generate_crc16_reverse_table(quint16 *table);
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// QByteArray crc16Reverse(const QByteArray& data);
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static void generate_crc16_reverse_table(quint16 table[256], quint16 poly = 0x8408)
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{
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for (int i = 0; i < 256; ++i) {
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quint16 crc = static_cast<quint16>(i);
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for (int j = 0; j < 8; ++j) {
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if (crc & 0x0001)
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crc = (crc >> 1) ^ poly;
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else
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crc >>= 1;
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}
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table[i] = crc;
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}
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}
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// 计算反射型CRC16-CCITT
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QByteArray crc16Reverse(const QByteArray& data)
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{
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static quint16 table[256];
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static bool tableInited = false;
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if (!tableInited) {
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generate_crc16_reverse_table(table);
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tableInited = true;
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}
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quint16 crc = 0x6363;
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for (auto b : data)
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crc = (crc >> 8) ^ table[(crc ^ static_cast<quint8>(b)) & 0xFF];
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QByteArray result;
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// 经过和python程序对比，说明CRC16的两个byte位置需调换
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// result.append(static_cast<char>((crc >> 8) & 0xFF));
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// result.append(static_cast<char>(crc & 0xFF));
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result.append(static_cast<char>(crc & 0xFF));
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result.append(static_cast<char>((crc >> 8) & 0xFF));
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return result;
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}
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