47 lines
883 B
C++
47 lines
883 B
C++
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#include "hdlcCrc.h"
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HdlcCrc::HdlcCrc(HdlcCrcTable* crcTable) {
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_crcTable = crcTable;
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}
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void HdlcCrc::resetFcs() {
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_fcs = CRC_RESET_VAL;
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_calcFcs[0] = _calcFcs[1];
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_calcFcs[1] = _fcs;
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_count = 0;
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}
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void HdlcCrc::calcFcs(byte newByte) {
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_fcs = (_fcs >> 8) ^ _crcTable->getValue((_fcs ^ newByte) & 0xff);
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_rxFcs[0] = _rxFcs[1];
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_rxFcs[1] = newByte;
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_calcFcs[0] = _calcFcs[1];
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_calcFcs[1] = _calcFcs[2];
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_calcFcs[2] = _fcs;
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_count++;
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}
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byte HdlcCrc::getFcsL() {
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return (_fcs & 0xff) ^ 0xff;
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}
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byte HdlcCrc::getFcsH() {
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return (_fcs >> 8) ^ 0xff;
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}
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boolean HdlcCrc::checkFcs() {
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boolean result = false;
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byte calcFcsL = (_calcFcs[0] & 0xff) ^ 0xff;
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byte calcFcsH = (_calcFcs[0] >> 8) ^ 0xff;
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if (_count > 2) {
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if (_rxFcs[0] == calcFcsL) {
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if (_rxFcs[1] == calcFcsH) {
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result = true;
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}
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}
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}
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return result;
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}
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