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+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#ifndef ART_LIBARTBASE_BASE_BIT_VECTOR_H_
+#define ART_LIBARTBASE_BASE_BIT_VECTOR_H_
+
+#include <stdint.h>
+#include <iterator>
+
+#include "base/bit_utils.h"
+#include "globals.h"
+
+namespace art {
+
+class Allocator;
+
+/*
+ * Expanding bitmap, used for tracking resources.  Bits are numbered starting
+ * from zero.  All operations on a BitVector are unsynchronized.
+ */
+class BitVector {
+ public:
+  class IndexContainer;
+
+  /**
+   * @brief Convenient iterator across the indexes of the BitVector's set bits.
+   *
+   * @details IndexIterator is a Forward iterator (C++11: 24.2.5) from the lowest
+   * to the highest index of the BitVector's set bits. Instances can be retrieved
+   * only through BitVector::Indexes() which returns an IndexContainer wrapper
+   * object with begin() and end() suitable for range-based loops:
+   *   for (uint32_t idx : bit_vector.Indexes()) {
+   *     // Use idx.
+   *   }
+   */
+  class IndexIterator :
+      std::iterator<std::forward_iterator_tag, uint32_t, ptrdiff_t, void, uint32_t> {
+   public:
+    bool operator==(const IndexIterator& other) const;
+
+    bool operator!=(const IndexIterator& other) const {
+      return !(*this == other);
+    }
+
+    uint32_t operator*() const;
+
+    IndexIterator& operator++();
+
+    IndexIterator operator++(int);
+
+    // Helper function to check for end without comparing with bit_vector.Indexes().end().
+    bool Done() const {
+      return bit_index_ == BitSize();
+    }
+
+   private:
+    struct begin_tag { };
+    struct end_tag { };
+
+    IndexIterator(const BitVector* bit_vector, begin_tag);
+    IndexIterator(const BitVector* bit_vector, end_tag);
+
+    uint32_t BitSize() const {
+      return storage_size_ * kWordBits;
+    }
+
+    uint32_t FindIndex(uint32_t start_index) const;
+    const uint32_t* const bit_storage_;
+    const uint32_t storage_size_;  // Size of vector in words.
+    uint32_t bit_index_;           // Current index (size in bits).
+
+    friend class BitVector::IndexContainer;
+  };
+
+  /**
+   * @brief BitVector wrapper class for iteration across indexes of set bits.
+   */
+  class IndexContainer {
+   public:
+    explicit IndexContainer(const BitVector* bit_vector) : bit_vector_(bit_vector) { }
+
+    IndexIterator begin() const;
+    IndexIterator end() const;
+
+   private:
+    const BitVector* const bit_vector_;
+  };
+
+  // MoveConstructible but not MoveAssignable, CopyConstructible or CopyAssignable.
+
+  BitVector(const BitVector& other) = delete;
+  BitVector& operator=(const BitVector& other) = delete;
+
+  BitVector(BitVector&& other)
+      : storage_(other.storage_),
+        storage_size_(other.storage_size_),
+        allocator_(other.allocator_),
+        expandable_(other.expandable_) {
+    other.storage_ = nullptr;
+    other.storage_size_ = 0u;
+  }
+
+  BitVector(uint32_t start_bits,
+            bool expandable,
+            Allocator* allocator);
+
+  BitVector(bool expandable,
+            Allocator* allocator,
+            uint32_t storage_size,
+            uint32_t* storage);
+
+  BitVector(const BitVector& src,
+            bool expandable,
+            Allocator* allocator);
+
+  virtual ~BitVector();
+
+  // The number of words necessary to encode bits.
+  static constexpr uint32_t BitsToWords(uint32_t bits) {
+    return RoundUp(bits, kWordBits) / kWordBits;
+  }
+
+  // Mark the specified bit as "set".
+  void SetBit(uint32_t idx) {
+    /*
+     * TUNING: this could have pathologically bad growth/expand behavior.  Make sure we're
+     * not using it badly or change resize mechanism.
+     */
+    if (idx >= storage_size_ * kWordBits) {
+      EnsureSize(idx);
+    }
+    storage_[WordIndex(idx)] |= BitMask(idx);
+  }
+
+  // Mark the specified bit as "unset".
+  void ClearBit(uint32_t idx) {
+    // If the index is over the size, we don't have to do anything, it is cleared.
+    if (idx < storage_size_ * kWordBits) {
+      // Otherwise, go ahead and clear it.
+      storage_[WordIndex(idx)] &= ~BitMask(idx);
+    }
+  }
+
+  // Determine whether or not the specified bit is set.
+  bool IsBitSet(uint32_t idx) const {
+    // If the index is over the size, whether it is expandable or not, this bit does not exist:
+    // thus it is not set.
+    return (idx < (storage_size_ * kWordBits)) && IsBitSet(storage_, idx);
+  }
+
+  // Mark all bits bit as "clear".
+  void ClearAllBits();
+
+  // Mark specified number of bits as "set". Cannot set all bits like ClearAll since there might
+  // be unused bits - setting those to one will confuse the iterator.
+  void SetInitialBits(uint32_t num_bits);
+
+  void Copy(const BitVector* src);
+
+  // Intersect with another bit vector.
+  void Intersect(const BitVector* src2);
+
+  // Union with another bit vector.
+  bool Union(const BitVector* src);
+
+  // Set bits of union_with that are not in not_in.
+  bool UnionIfNotIn(const BitVector* union_with, const BitVector* not_in);
+
+  void Subtract(const BitVector* src);
+
+  // Are we equal to another bit vector?  Note: expandability attributes must also match.
+  bool Equal(const BitVector* src) const;
+
+  /**
+   * @brief Are all the bits set the same?
+   * @details expandability and size can differ as long as the same bits are set.
+   */
+  bool SameBitsSet(const BitVector *src) const;
+
+  bool IsSubsetOf(const BitVector *other) const;
+
+  // Count the number of bits that are set.
+  uint32_t NumSetBits() const;
+
+  // Count the number of bits that are set in range [0, end).
+  uint32_t NumSetBits(uint32_t end) const;
+
+  IndexContainer Indexes() const {
+    return IndexContainer(this);
+  }
+
+  uint32_t GetStorageSize() const {
+    return storage_size_;
+  }
+
+  bool IsExpandable() const {
+    return expandable_;
+  }
+
+  uint32_t GetRawStorageWord(size_t idx) const {
+    return storage_[idx];
+  }
+
+  uint32_t* GetRawStorage() {
+    return storage_;
+  }
+
+  const uint32_t* GetRawStorage() const {
+    return storage_;
+  }
+
+  size_t GetSizeOf() const {
+    return storage_size_ * kWordBytes;
+  }
+
+  /**
+   * @return the highest bit set, -1 if none are set
+   */
+  int GetHighestBitSet() const;
+
+  // Minimum number of bits required to store this vector, 0 if none are set.
+  size_t GetNumberOfBits() const {
+    return GetHighestBitSet() + 1;
+  }
+
+  // Is bit set in storage. (No range check.)
+  static bool IsBitSet(const uint32_t* storage, uint32_t idx) {
+    return (storage[WordIndex(idx)] & BitMask(idx)) != 0;
+  }
+
+  // Number of bits set in range [0, end) in storage. (No range check.)
+  static uint32_t NumSetBits(const uint32_t* storage, uint32_t end);
+
+  // Fill given memory region with the contents of the vector and zero padding.
+  void CopyTo(void* dst, size_t len) const {
+    DCHECK_LE(static_cast<size_t>(GetHighestBitSet() + 1), len * kBitsPerByte);
+    size_t vec_len = GetSizeOf();
+    if (vec_len < len) {
+      void* dst_padding = reinterpret_cast<uint8_t*>(dst) + vec_len;
+      memcpy(dst, storage_, vec_len);
+      memset(dst_padding, 0, len - vec_len);
+    } else {
+      memcpy(dst, storage_, len);
+    }
+  }
+
+  void Dump(std::ostream& os, const char* prefix) const;
+
+  Allocator* GetAllocator() const;
+
+ private:
+  /**
+   * @brief Dump the bitvector into buffer in a 00101..01 format.
+   * @param buffer the ostringstream used to dump the bitvector into.
+   */
+  void DumpHelper(const char* prefix, std::ostringstream& buffer) const;
+
+  // Ensure there is space for a bit at idx.
+  void EnsureSize(uint32_t idx);
+
+  // The index of the word within storage.
+  static constexpr uint32_t WordIndex(uint32_t idx) {
+    return idx >> 5;
+  }
+
+  // A bit mask to extract the bit for the given index.
+  static constexpr uint32_t BitMask(uint32_t idx) {
+    return 1 << (idx & 0x1f);
+  }
+
+  static constexpr uint32_t kWordBytes = sizeof(uint32_t);
+  static constexpr uint32_t kWordBits = kWordBytes * 8;
+
+  uint32_t*  storage_;            // The storage for the bit vector.
+  uint32_t   storage_size_;       // Current size, in 32-bit words.
+  Allocator* const allocator_;    // Allocator if expandable.
+  const bool expandable_;         // Should the bitmap expand if too small?
+};
+
+
+}  // namespace art
+
+#endif  // ART_LIBARTBASE_BASE_BIT_VECTOR_H_