62 lines
1.4 KiB
C++
62 lines
1.4 KiB
C++
#include "StateChecksum.h"
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#include <sstream>
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void Hasher::appendBytes(const void* data, std::size_t byteCount)
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{
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const unsigned char* bytes = static_cast<const unsigned char*>(data);
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for (std::size_t i = 0; i < byteCount; ++i)
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{
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m_state ^= bytes[i];
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m_state *= 1099511628211ull; // FNV-1a 64-bit prime
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}
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}
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void Hasher::append(float value)
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{
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// Normalize -0.0f to +0.0f so the two equal values share a fingerprint.
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if (value == 0.0f) { value = 0.0f; }
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appendBytes(&value, sizeof(value));
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}
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void Hasher::append(double value)
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{
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if (value == 0.0) { value = 0.0; }
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appendBytes(&value, sizeof(value));
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}
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void Hasher::append(const QPoint& point)
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{
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const int coords[2] = { point.x(), point.y() };
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appendBytes(coords, sizeof(coords));
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}
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void Hasher::append(const QPointF& point)
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{
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append(point.x());
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append(point.y());
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}
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void Hasher::append(const QVector2D& vector)
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{
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append(vector.x());
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append(vector.y());
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}
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void Hasher::append(const std::string& text)
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{
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appendBytes(text.data(), text.size());
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// Length terminator so "ab"+"c" and "a"+"bc" do not collide.
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const std::size_t length = text.size();
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appendBytes(&length, sizeof(length));
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}
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std::uint64_t fingerprintRng(const std::mt19937& rng)
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{
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std::ostringstream stream;
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stream << rng; // full internal state as space-separated integers
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Hasher hasher;
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hasher.append(stream.str());
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return hasher.getValue();
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}
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