744998e666
R=robertphillips@google.com Author: bsalomon@google.com Review URL: https://codereview.chromium.org/510053003
103 lines
2.3 KiB
C++
103 lines
2.3 KiB
C++
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/*
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* Copyright 2011 Google Inc.
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*
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* Use of this source code is governed by a BSD-style license that can be
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* found in the LICENSE file.
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*/
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#ifndef GrBinHashKey_DEFINED
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#define GrBinHashKey_DEFINED
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#include "GrTypes.h"
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/**
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* GrBinHashKey is a hash key class that can take a data chunk of any predetermined
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* length. The hash function used is the One-at-a-Time Hash
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* (http://burtleburtle.net/bob/hash/doobs.html).
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*/
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template<size_t KEY_SIZE>
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class GrBinHashKey {
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public:
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enum { kKeySize = KEY_SIZE };
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GrBinHashKey() {
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this->reset();
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}
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void reset() {
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fHash = 0;
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#ifdef SK_DEBUG
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fIsValid = false;
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#endif
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}
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void setKeyData(const uint32_t* SK_RESTRICT data) {
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SK_COMPILE_ASSERT(KEY_SIZE % 4 == 0, key_size_mismatch);
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memcpy(&fData, data, KEY_SIZE);
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uint32_t hash = 0;
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size_t len = KEY_SIZE;
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while (len >= 4) {
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hash += *data++;
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hash += (hash << 10);
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hash ^= (hash >> 6);
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len -= 4;
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}
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hash += (hash << 3);
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hash ^= (hash >> 11);
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hash += (hash << 15);
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#ifdef SK_DEBUG
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fIsValid = true;
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#endif
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fHash = hash;
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}
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bool operator==(const GrBinHashKey<KEY_SIZE>& key) const {
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SkASSERT(fIsValid && key.fIsValid);
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if (fHash != key.fHash) {
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return false;
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}
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for (size_t i = 0; i < SK_ARRAY_COUNT(fData); ++i) {
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if (fData[i] != key.fData[i]) {
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return false;
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}
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}
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return true;
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}
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bool operator<(const GrBinHashKey<KEY_SIZE>& key) const {
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SkASSERT(fIsValid && key.fIsValid);
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for (size_t i = 0; i < SK_ARRAY_COUNT(fData); ++i) {
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if (fData[i] < key.fData[i]) {
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return true;
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} else if (fData[i] > key.fData[i]) {
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return false;
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}
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}
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return false;
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}
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uint32_t getHash() const {
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SkASSERT(fIsValid);
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return fHash;
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}
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const uint8_t* getData() const {
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SkASSERT(fIsValid);
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return reinterpret_cast<const uint8_t*>(fData);
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}
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private:
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uint32_t fHash;
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uint32_t fData[KEY_SIZE / sizeof(uint32_t)]; // Buffer for key storage.
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#ifdef SK_DEBUG
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public:
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bool fIsValid;
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#endif
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};
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#endif
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