93 lines
2.4 KiB
C++
93 lines
2.4 KiB
C++
/*
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* Copyright (C) 2014 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#ifndef __BYTE_BUCKET_ARRAY_H
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#define __BYTE_BUCKET_ARRAY_H
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#include <cstdint>
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#include <cstring>
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#include "android-base/logging.h"
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namespace android {
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/**
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* Stores a sparsely populated array. Has a fixed size of 256
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* (number of entries that a byte can represent).
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*/
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template <typename T>
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class ByteBucketArray {
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public:
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ByteBucketArray() : default_() { memset(buckets_, 0, sizeof(buckets_)); }
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~ByteBucketArray() {
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for (size_t i = 0; i < kNumBuckets; i++) {
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if (buckets_[i] != NULL) {
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delete[] buckets_[i];
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}
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}
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memset(buckets_, 0, sizeof(buckets_));
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}
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inline size_t size() const { return kNumBuckets * kBucketSize; }
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inline const T& get(size_t index) const { return (*this)[index]; }
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const T& operator[](size_t index) const {
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if (index >= size()) {
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return default_;
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}
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uint8_t bucket_index = static_cast<uint8_t>(index) >> 4;
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T* bucket = buckets_[bucket_index];
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if (bucket == NULL) {
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return default_;
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}
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return bucket[0x0f & static_cast<uint8_t>(index)];
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}
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T& editItemAt(size_t index) {
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CHECK(index < size()) << "ByteBucketArray.editItemAt(index=" << index
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<< ") with size=" << size();
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uint8_t bucket_index = static_cast<uint8_t>(index) >> 4;
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T* bucket = buckets_[bucket_index];
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if (bucket == NULL) {
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bucket = buckets_[bucket_index] = new T[kBucketSize]();
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}
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return bucket[0x0f & static_cast<uint8_t>(index)];
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}
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bool set(size_t index, const T& value) {
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if (index >= size()) {
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return false;
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}
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editItemAt(index) = value;
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return true;
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}
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private:
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enum { kNumBuckets = 16, kBucketSize = 16 };
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T* buckets_[kNumBuckets];
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T default_;
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};
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} // namespace android
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#endif // __BYTE_BUCKET_ARRAY_H
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