NetBitStreamReader.h

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// Copyright Epic Games, Inc. All Rights Reserved.
 
#pragma once
 
#include "CoreTypes.h"
 
namespace UE::Net
{
 
class FNetBitStreamReader
{
public:
    IRISCORE_API FNetBitStreamReader();
    IRISCORE_API ~FNetBitStreamReader();
 
    IRISCORE_API void InitBits(const void* Buffer, uint32 BitCount);
 
    IRISCORE_API uint32 ReadBits(uint32 BitCount);
 
    bool ReadBool() { return ReadBits(1) & 1U; }
 
    IRISCORE_API void ReadBitStream(uint32* Dst, uint32 BitCount);
 
    IRISCORE_API void Seek(uint32 BitPosition);
 
    inline uint32 GetPosBytes() const { return (BufferBitPosition - BufferBitStartOffset + 7) >> 3U; }
 
    inline uint32 GetPosBits() const { return BufferBitPosition - BufferBitStartOffset; }
 
    inline uint32 GetAbsolutePosBits() const { return BufferBitPosition; }
 
    inline uint32 GetBitsLeft() const { return (OverflowBitCount ? 0U : (BufferBitCapacity - BufferBitPosition)); }
 
    IRISCORE_API void DoOverflow();
    
    inline bool IsOverflown() const { return OverflowBitCount != 0; }
 
    IRISCORE_API FNetBitStreamReader CreateSubstream(uint32 MaxBitCount = ~0U);
 
    IRISCORE_API void CommitSubstream(FNetBitStreamReader& Substream);
 
    IRISCORE_API void DiscardSubstream(FNetBitStreamReader& Substream);
 
private:
    const uint32* Buffer;
    // The BufferBitCapacity is an absolute bit position indicating the bit after the last valid bit position to read.
    uint32 BufferBitCapacity;
    // For substreams this indicate the absolute bit position in the buffer where it will start reading
    uint32 BufferBitStartOffset;
    uint32 BufferBitPosition;
    uint32 PendingWord;
    uint32 OverflowBitCount;
 
    uint32 bHasSubstream : 1;
    uint32 bIsSubstream : 1;
    uint32 bIsInvalid : 1;
};
 
}
 
// Always report the actual bitstream position, even on overflow. This normally allows for better comparisons between sending and receiving side when bitstream errors occur.
inline uint32 GetBitStreamPositionForNetTrace(const UE::Net::FNetBitStreamReader& Stream) { return Stream.GetAbsolutePosBits(); }