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o3de/Code/Framework/AzNetworking/AzNetworking/DataStructures/RingBufferBitset.h

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3.7 KiB
C++

/*
* Copyright (c) Contributors to the Open 3D Engine Project. For complete copyright and license terms please see the LICENSE at the root of this distribution.
*
* SPDX-License-Identifier: Apache-2.0 OR MIT
*
*/
#pragma once
#include <AzCore/Math/MathUtils.h>
#include <AzCore/std/containers/array.h>
#include <AzCore/RTTI/TypeSafeIntegral.h>
namespace AzNetworking
{
using BitsetChunk = uint32_t;
//! @class RingBufferBitset
//! @brief fixed size data structure optimized for storing and rotating large numbers of bits.
template <uint32_t SIZE>
class RingbufferBitset
{
public:
static constexpr uint32_t NumBitsetChunkedBits = AZ::Log2(BitsetChunk(~0));
static constexpr uint32_t RingbufferContainerSize = SIZE / NumBitsetChunkedBits;
static_assert((SIZE % NumBitsetChunkedBits) == 0, "RingbufferBitset must be a multiple of NumBitsetChunkedBits");
using RingbufferContainer = AZStd::array<BitsetChunk, RingbufferContainerSize>;
RingbufferBitset();
~RingbufferBitset() = default;
//! Resets the bitset to all empty.
void Reset();
//! Gets the current value of the specified bit.
//! @param index index of the bit to retrieve the value of
//! @return boolean true if the bit is set, false otherwise
bool GetBit(uint32_t index) const;
//! Sets the specified bit to the provided value.
//! @param index index of the bit to set
//! @param value value to set the bit to
void SetBit(uint32_t index, bool value);
//! Returns the number of accessible bits in this ringbuffer bitset.
//! @return the number of accessible bits in this ringbuffer bitset
uint32_t GetValidBitCount() const;
//! Pushes back the specified number of bits padding with zero bits.
//! @param numBits the number of bits to push into the bitset
void PushBackBits(uint32_t numBits);
//! Retrieves a single element from the ringbuffer bitset.
//! @param elementIndex the index of the ringbuffer element to retrieve
//! @return the requested bitset element
const BitsetChunk& GetBitsetElement(uint32_t elementIndex) const;
//! Returns the number of bits that are unused in the head element.
//! @return the number of bits that are unused in the head element
uint32_t GetUnusedHeadBits() const;
private:
//! Converts the provided absolute index into a internal ring buffer element index.
//! @param absoluteIndex the absolute index value to convert to a ring-buffer index
//! @return the converted ring-buffer index
uint32_t GetChunkIndexHelper(uint32_t absoluteIndex) const;
//! Increments the internal head index.
void IncrementHead();
uint32_t m_headElementOffset = 0; //< What index is the first element in our ring buffer
uint32_t m_unusedHeadBits = NumBitsetChunkedBits; //< How many bits are unused in the head RingbufferContainer element
RingbufferContainer m_container;
};
//! Helper method for extracting a bit from a specific element.
//! @param element the specific element to get the bit from
//! @param bitIndex the index of the bit to retrieve
//! @return boolean true if the bit is set, false otherwise
template <typename TYPE>
bool GetBitHelper(TYPE element, uint32_t bitIndex);
//! A helper method for setting bits.
//! @param element the specific element to set the bit within
//! @param bitIndex the index of the bit to set
//! @param value the value to set the bit to
template <typename TYPE>
void SetBitHelper(TYPE &element, uint32_t bitIndex, bool value);
}
#include <AzNetworking/DataStructures/RingBufferBitset.inl>