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35 lines
803 B
C++
35 lines
803 B
C++
//
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// Created by Stepan Usatiuk on 26.04.2023.
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//
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#include "../includes/Buzhash.h"
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Buzhash::Buzhash(uint32_t blockSize) : blockSize(blockSize), history() {}
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uint32_t Buzhash::get() const {
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return cur;
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}
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uint32_t Buzhash::feed(uint8_t in) {
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cur = rotr32(cur, 1);
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if (history.size() >= blockSize) {
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auto oldest = history.back();
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history.pop_back();
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cur ^= rotr32(randomNumbers[oldest], blockSize);
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}
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history.emplace_front(in);
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cur ^= randomNumbers[in];
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return cur;
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}
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// Circular shift taken from: https://en.wikipedia.org/wiki/Circular_shift
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uint32_t Buzhash::rotr32(uint32_t value, unsigned int count) {
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const unsigned int mask = CHAR_BIT * sizeof(value) - 1;
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count &= mask;
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return (value >> count) | (value << (-count & mask));
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}
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