kc3-lang/angle/src/common/CircularBuffer.h

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• Author : Shahbaz Youssefi
  Date : 2021-10-14 23:14:37
  Hash : 7aba3bc5
  Message : Vulkan: Use a CircularBuffer helper class in SurfaceVk There are two instances of circular buffer in SurfaceVk. A common helper class is introduced by this change to consolidate the implementation. This is in preparation for a follow up change that introduces yet another circular buffer in this class. Bug: angleproject:6401 Change-Id: Id01b585567310a2528888114239a5c80ff93f1ee Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/3225084 Commit-Queue: Shahbaz Youssefi <syoussefi@chromium.org> Reviewed-by: Ian Elliott <ianelliott@google.com> Reviewed-by: Jamie Madill <jmadill@chromium.org>

• src/common/CircularBuffer.h

• //
  // Copyright 2021 The ANGLE Project Authors. All rights reserved.
  // Use of this source code is governed by a BSD-style license that can be
  // found in the LICENSE file.
  //
  // CircularBuffer.h:
  //   An array class with an index that loops through the elements.
  //
  
  #ifndef COMMON_CIRCULARBUFFER_H_
  #define COMMON_CIRCULARBUFFER_H_
  
  #include "common/debug.h"
  
  #include <algorithm>
  #include <array>
  
  namespace angle
  {
  template <class T, size_t N, class Storage = std::array<T, N>>
  class CircularBuffer final
  {
    public:
      using value_type      = typename Storage::value_type;
      using size_type       = typename Storage::size_type;
      using reference       = typename Storage::reference;
      using const_reference = typename Storage::const_reference;
      using pointer         = typename Storage::pointer;
      using const_pointer   = typename Storage::const_pointer;
      using iterator        = typename Storage::iterator;
      using const_iterator  = typename Storage::const_iterator;
  
      CircularBuffer();
      CircularBuffer(const value_type &value);
  
      CircularBuffer(const CircularBuffer<T, N, Storage> &other);
      CircularBuffer(CircularBuffer<T, N, Storage> &&other);
  
      CircularBuffer<T, N, Storage> &operator=(const CircularBuffer<T, N, Storage> &other);
      CircularBuffer<T, N, Storage> &operator=(CircularBuffer<T, N, Storage> &&other);
  
      ~CircularBuffer();
  
      // begin() and end() are used to iterate over all elements regardless of the current position of
      // the front of the buffer.  Useful for initialization and clean up, as otherwise only the front
      // element is expected to be accessed.
      iterator begin();
      const_iterator begin() const;
  
      iterator end();
      const_iterator end() const;
  
      size_type size() const;
  
      reference front();
      const_reference front() const;
  
      void swap(CircularBuffer<T, N, Storage> &other);
  
      // Move the front forward to the next index, looping back to the beginning if the end of the
      // array is reached.
      void next();
  
    private:
      Storage mData;
      size_type mFrontIndex;
  };
  
  template <class T, size_t N, class Storage>
  CircularBuffer<T, N, Storage>::CircularBuffer() : mFrontIndex(0)
  {}
  
  template <class T, size_t N, class Storage>
  CircularBuffer<T, N, Storage>::CircularBuffer(const value_type &value) : CircularBuffer()
  {
      std::fill(begin(), end(), value);
  }
  
  template <class T, size_t N, class Storage>
  CircularBuffer<T, N, Storage>::CircularBuffer(const CircularBuffer<T, N, Storage> &other)
  {
      *this = other;
  }
  
  template <class T, size_t N, class Storage>
  CircularBuffer<T, N, Storage>::CircularBuffer(CircularBuffer<T, N, Storage> &&other)
      : CircularBuffer()
  {
      swap(other);
  }
  
  template <class T, size_t N, class Storage>
  CircularBuffer<T, N, Storage> &CircularBuffer<T, N, Storage>::operator=(
      const CircularBuffer<T, N, Storage> &other)
  {
      std::copy(other.begin(), other.end(), begin());
      mFrontIndex = other.mFrontIndex;
      return *this;
  }
  
  template <class T, size_t N, class Storage>
  CircularBuffer<T, N, Storage> &CircularBuffer<T, N, Storage>::operator=(
      CircularBuffer<T, N, Storage> &&other)
  {
      swap(other);
      return *this;
  }
  
  template <class T, size_t N, class Storage>
  CircularBuffer<T, N, Storage>::~CircularBuffer() = default;
  
  template <class T, size_t N, class Storage>
  ANGLE_INLINE typename CircularBuffer<T, N, Storage>::iterator CircularBuffer<T, N, Storage>::begin()
  {
      return mData.begin();
  }
  
  template <class T, size_t N, class Storage>
  ANGLE_INLINE typename CircularBuffer<T, N, Storage>::const_iterator
  CircularBuffer<T, N, Storage>::begin() const
  {
      return mData.begin();
  }
  
  template <class T, size_t N, class Storage>
  ANGLE_INLINE typename CircularBuffer<T, N, Storage>::iterator CircularBuffer<T, N, Storage>::end()
  {
      return mData.end();
  }
  
  template <class T, size_t N, class Storage>
  ANGLE_INLINE typename CircularBuffer<T, N, Storage>::const_iterator
  CircularBuffer<T, N, Storage>::end() const
  {
      return mData.end();
  }
  
  template <class T, size_t N, class Storage>
  ANGLE_INLINE typename CircularBuffer<T, N, Storage>::size_type CircularBuffer<T, N, Storage>::size()
      const
  {
      return N;
  }
  
  template <class T, size_t N, class Storage>
  ANGLE_INLINE typename CircularBuffer<T, N, Storage>::reference
  CircularBuffer<T, N, Storage>::front()
  {
      ASSERT(mFrontIndex < size());
      return mData[mFrontIndex];
  }
  
  template <class T, size_t N, class Storage>
  ANGLE_INLINE typename CircularBuffer<T, N, Storage>::const_reference
  CircularBuffer<T, N, Storage>::front() const
  {
      ASSERT(mFrontIndex < size());
      return mData[mFrontIndex];
  }
  
  template <class T, size_t N, class Storage>
  void CircularBuffer<T, N, Storage>::swap(CircularBuffer<T, N, Storage> &other)
  {
      std::swap(mData, other.mData);
      std::swap(mFrontIndex, other.mFrontIndex);
  }
  
  template <class T, size_t N, class Storage>
  void CircularBuffer<T, N, Storage>::next()
  {
      mFrontIndex = (mFrontIndex + 1) % size();
  }
  }  // namespace angle
  
  #endif  // COMMON_CIRCULARBUFFER_H_