5a761209d2
Batch #832 by ragnarok-clanker: 0 byte-identical, 2 confirmed by peer review. - fn_00162 XxHash32: logic confirmed by peer review - fn_00163 FinalizeXxHash32: logic confirmed by peer review Reviewed-by: ragnarok-clanker Adds to the build: Source/Utility/XxHash32.cpp
67 lines
1.9 KiB
C++
67 lines
1.9 KiB
C++
#include "Utility/XxHash32.h"
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#include <bit>
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#include <cstring>
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namespace {
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// INLINED
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std::uint32_t ReadWord(const unsigned char* data) {
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std::uint32_t value;
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std::memcpy(&value, data, sizeof(value));
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return value;
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}
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}
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// FUNCTION: fn_00163
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std::uint32_t FinalizeXxHash32(std::uint32_t hash, const void* data, std::uint32_t remaining, int) {
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const auto* current = static_cast<const unsigned char*>(data);
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remaining &= 15u;
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while (remaining >= 4u) {
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hash += ReadWord(current) * 0xC2B2AE3Du;
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hash = std::rotl(hash, 17) * 0x27D4EB2Fu;
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current += 4;
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remaining -= 4;
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}
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while (remaining != 0) {
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hash += *current++ * 0x165667B1u;
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hash = std::rotl(hash, 11) * 0x9E3779B1u;
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--remaining;
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}
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hash ^= hash >> 15;
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hash *= 0x85EBCA77u;
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hash ^= hash >> 13;
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hash *= 0xC2B2AE3Du;
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hash ^= hash >> 16;
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return hash;
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}
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// FUNCTION: fn_00162
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std::uint32_t XxHash32(const void* data, std::uint32_t length, std::uint32_t seed) {
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const auto* current = static_cast<const unsigned char*>(data);
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std::uint32_t hash;
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if (length >= 16u) {
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const unsigned char* limit = current + length - 15u;
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std::uint32_t first = seed + 0x24234428u;
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std::uint32_t second = seed + 0x85EBCA77u;
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std::uint32_t third = seed;
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std::uint32_t fourth = seed - 0x9E3779B1u;
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do {
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first = std::rotl(first + ReadWord(current) * 0x85EBCA77u, 13) * 0x9E3779B1u;
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second = std::rotl(second + ReadWord(current + 4) * 0x85EBCA77u, 13) * 0x9E3779B1u;
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third = std::rotl(third + ReadWord(current + 8) * 0x85EBCA77u, 13) * 0x9E3779B1u;
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fourth = std::rotl(fourth + ReadWord(current + 12) * 0x85EBCA77u, 13) * 0x9E3779B1u;
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current += 16;
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} while (current < limit);
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hash = std::rotl(first, 1) + std::rotl(second, 7) + std::rotl(third, 12) + std::rotl(fourth, 18);
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} else {
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hash = seed + 0x165667B1u;
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}
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return FinalizeXxHash32(hash + length, current, length & 15u, 1);
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}
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