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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"
/**
* Hash function 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<typename Entry, size_t KeySize>
class GrBinHashKey {
public:
GrBinHashKey()
: fHash(0)
#if GR_DEBUG
, fIsValid(false)
#endif
{}
GrBinHashKey(const GrBinHashKey<Entry, KeySize>& other) {
*this = other;
}
GrBinHashKey<Entry, KeySize>& operator=(const GrBinHashKey<Entry,
KeySize>& other) {
memcpy(this, &other, sizeof(*this));
return *this;
}
~GrBinHashKey() {
}
void setKeyData(const uint32_t *data) {
GrAssert(GrIsALIGN4(KeySize));
memcpy(&fData, data, KeySize);
fHash = 0;
size_t len = KeySize;
while (len >= 4) {
fHash += *data++;
fHash += (fHash << 10);
fHash ^= (fHash >> 6);
len -= 4;
}
fHash += (fHash << 3);
fHash ^= (fHash >> 11);
fHash += (fHash << 15);
#if GR_DEBUG
fIsValid = true;
#endif
}
int compare(const GrBinHashKey<Entry, KeySize>& key) const {
GrAssert(fIsValid && key.fIsValid);
return memcmp(fData, key.fData, KeySize);
}
static bool
EQ(const Entry& entry, const GrBinHashKey<Entry, KeySize>& key) {
GrAssert(key.fIsValid);
return 0 == entry.compare(key);
}
static bool
LT(const Entry& entry, const GrBinHashKey<Entry, KeySize>& key) {
GrAssert(key.fIsValid);
return entry.compare(key) < 0;
}
uint32_t getHash() const {
GrAssert(fIsValid);
return fHash;
}
private:
uint32_t fHash;
uint8_t fData[KeySize]; //Buffer for key storage
#if GR_DEBUG
public:
bool fIsValid;
#endif
};
#endif
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