1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/gfx/skia/trunk/src/gpu/GrBinHashKey.h Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,102 @@
1.4 +
1.5 +/*
1.6 + * Copyright 2011 Google Inc.
1.7 + *
1.8 + * Use of this source code is governed by a BSD-style license that can be
1.9 + * found in the LICENSE file.
1.10 + */
1.11 +
1.12 +
1.13 +#ifndef GrBinHashKey_DEFINED
1.14 +#define GrBinHashKey_DEFINED
1.15 +
1.16 +#include "GrTypes.h"
1.17 +
1.18 +/**
1.19 + * GrBinHashKey is a hash key class that can take a data chunk of any predetermined
1.20 + * length. The hash function used is the One-at-a-Time Hash
1.21 + * (http://burtleburtle.net/bob/hash/doobs.html).
1.22 + */
1.23 +template<size_t KEY_SIZE>
1.24 +class GrBinHashKey {
1.25 +public:
1.26 + enum { kKeySize = KEY_SIZE };
1.27 +
1.28 + GrBinHashKey() {
1.29 + this->reset();
1.30 + }
1.31 +
1.32 + void reset() {
1.33 + fHash = 0;
1.34 +#ifdef SK_DEBUG
1.35 + fIsValid = false;
1.36 +#endif
1.37 + }
1.38 +
1.39 + void setKeyData(const uint32_t* SK_RESTRICT data) {
1.40 + SK_COMPILE_ASSERT(KEY_SIZE % 4 == 0, key_size_mismatch);
1.41 + memcpy(&fData, data, KEY_SIZE);
1.42 +
1.43 + uint32_t hash = 0;
1.44 + size_t len = KEY_SIZE;
1.45 + while (len >= 4) {
1.46 + hash += *data++;
1.47 + hash += (hash << 10);
1.48 + hash ^= (hash >> 6);
1.49 + len -= 4;
1.50 + }
1.51 + hash += (hash << 3);
1.52 + hash ^= (hash >> 11);
1.53 + hash += (hash << 15);
1.54 +#ifdef SK_DEBUG
1.55 + fIsValid = true;
1.56 +#endif
1.57 + fHash = hash;
1.58 + }
1.59 +
1.60 + bool operator==(const GrBinHashKey<KEY_SIZE>& key) const {
1.61 + SkASSERT(fIsValid && key.fIsValid);
1.62 + if (fHash != key.fHash) {
1.63 + return false;
1.64 + }
1.65 + for (size_t i = 0; i < SK_ARRAY_COUNT(fData); ++i) {
1.66 + if (fData[i] != key.fData[i]) {
1.67 + return false;
1.68 + }
1.69 + }
1.70 + return true;
1.71 + }
1.72 +
1.73 + bool operator<(const GrBinHashKey<KEY_SIZE>& key) const {
1.74 + SkASSERT(fIsValid && key.fIsValid);
1.75 + for (size_t i = 0; i < SK_ARRAY_COUNT(fData); ++i) {
1.76 + if (fData[i] < key.fData[i]) {
1.77 + return true;
1.78 + } else if (fData[i] > key.fData[i]) {
1.79 + return false;
1.80 + }
1.81 + }
1.82 + return false;
1.83 + }
1.84 +
1.85 + uint32_t getHash() const {
1.86 + SkASSERT(fIsValid);
1.87 + return fHash;
1.88 + }
1.89 +
1.90 + const uint8_t* getData() const {
1.91 + SkASSERT(fIsValid);
1.92 + return reinterpret_cast<const uint8_t*>(fData);
1.93 + }
1.94 +
1.95 +private:
1.96 + uint32_t fHash;
1.97 + uint32_t fData[KEY_SIZE / sizeof(uint32_t)]; // Buffer for key storage.
1.98 +
1.99 +#ifdef SK_DEBUG
1.100 +public:
1.101 + bool fIsValid;
1.102 +#endif
1.103 +};
1.104 +
1.105 +#endif
