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