Justin Marshall
93 lines
2.7 KiB
C++
93 lines
2.7 KiB
C++
#include "hashindex.h"
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#include <cstdlib>
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void idHashIndex::InternalInit(const int initialHashSize,
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const int initialIndexSize) {
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hash = nullptr;
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indexChain = nullptr;
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hashSize = (std::max)(initialHashSize, 1);
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indexSize = (std::max)(initialIndexSize, 1);
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granularity = 1024;
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hashMask = hashSize - 1;
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lookupMask = 0;
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}
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void idHashIndex::Free() {
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delete[] hash;
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delete[] indexChain;
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hash = nullptr;
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indexChain = nullptr;
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lookupMask = 0;
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}
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void idHashIndex::Allocate(int newHashSize, int newIndexSize) {
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delete[] hash;
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delete[] indexChain;
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hash = nullptr;
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indexChain = nullptr;
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newHashSize = NextPowerOfTwo((std::max)(newHashSize, 1));
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newIndexSize = (std::max)(newIndexSize, 1);
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hashSize = newHashSize;
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indexSize = newIndexSize;
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hashMask = hashSize - 1;
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lookupMask = 0;
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hash = new (std::nothrow) int[hashSize];
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indexChain = new (std::nothrow) int[indexSize];
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if (hash == nullptr || indexChain == nullptr) {
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delete[] hash;
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delete[] indexChain;
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hash = nullptr;
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indexChain = nullptr;
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return;
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}
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std::fill(hash, hash + hashSize, -1);
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std::fill(indexChain, indexChain + indexSize, -1);
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lookupMask = -1;
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}
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void idHashIndex::ResizeIndex(const int requestedIndexSize) {
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if (requestedIndexSize <= indexSize) return;
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const int step = granularity > 0 ? granularity : 1024;
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const int newIndexSize = ((requestedIndexSize + step - 1) / step) * step;
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if (indexChain == nullptr) {
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indexSize = newIndexSize;
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return;
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}
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int* const oldChain = indexChain;
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indexChain = new (std::nothrow) int[newIndexSize];
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if (indexChain == nullptr) {
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indexChain = oldChain;
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return;
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}
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std::copy(oldChain, oldChain + indexSize, indexChain);
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std::fill(indexChain + indexSize, indexChain + newIndexSize, -1);
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delete[] oldChain;
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indexSize = newIndexSize;
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}
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int idHashIndex::GetSpread() const {
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if (hash == nullptr || hashSize <= 0) return 100;
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int* counts = new (std::nothrow) int[hashSize];
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if (counts == nullptr) return 100;
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int total = 0;
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for (int bucket = 0; bucket < hashSize; ++bucket) {
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counts[bucket] = 0;
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for (int index = hash[bucket]; index >= 0;
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index = indexChain[index]) ++counts[bucket];
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total += counts[bucket];
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}
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if (total <= 1) {
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delete[] counts;
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return 100;
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}
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const int average = total / hashSize;
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int error = 0;
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for (int bucket = 0; bucket < hashSize; ++bucket) {
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const int difference = std::abs(counts[bucket] - average);
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if (difference > 1) error += difference - 1;
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}
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delete[] counts;
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return 100 - 100 * error / total;
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}
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