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