43 lines
896 B
C++
43 lines
896 B
C++
#include "CyclicRedundancyChecker.h"
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void CyclicRedundancyChecker::createTable()
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{
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mTable = std::vector<unsigned long>(TABLE_SIZE, 0);
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unsigned long c{0};
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for (std::size_t n = 0; n < TABLE_SIZE; n++)
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{
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c = (unsigned long) n;
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for (int k = 0; k < 8; k++)
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{
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if (c & 1)
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{
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c = 0xedb88320L ^ (c >> 1);
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}
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else
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{
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c = c >> 1;
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}
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}
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mTable[n] = c;
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}
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mTableComputed = true;
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}
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void CyclicRedundancyChecker::addValue(unsigned char val)
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{
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if (!mTableComputed)
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{
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createTable();
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}
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mLastValue = mTable[(mLastValue ^ val) & 0xff] ^ (mLastValue >> 8);
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}
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uint32_t CyclicRedundancyChecker::getChecksum() const
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{
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return mLastValue ^ 0xffffffffL;
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}
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void CyclicRedundancyChecker::reset()
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{
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mLastValue = 0xffffffffL;
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}
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