// ByteStream.h
// Interfaces to the cByteBuffer class representing a ringbuffer of bytes
#pragma once
/** An object that can store incoming bytes and lets its clients read the bytes sequentially
The bytes are stored in a ringbuffer of constant size; if more than that size
is requested, the write operation fails.
The bytes stored can be retrieved using various ReadXXX functions; these assume that the needed
number of bytes are present in the buffer (ASSERT; for performance reasons).
The reading doesn't actually remove the bytes, it only moves the internal read ptr.
To remove the bytes, call CommitRead().
To re-start reading from the beginning, call ResetRead().
This class doesn't implement thread safety, the clients of this class need to provide
their own synchronization.
*/
class cByteBuffer
{
public:
cByteBuffer(size_t a_BufferSize);
~cByteBuffer();
/// Writes the bytes specified to the ringbuffer. Returns true if successful, false if not
bool Write(const char * a_Bytes, size_t a_Count);
/// Returns the number of bytes that can be successfully written to the ringbuffer
size_t GetFreeSpace(void) const;
/// Returns the number of bytes that are currently in the ringbuffer. Note GetReadableBytes()
size_t GetUsedSpace(void) const;
/// Returns the number of bytes that are currently available for reading (may be less than UsedSpace due to some data having been read already)
size_t GetReadableSpace(void) const;
/// Returns the current data start index. For debugging purposes.
size_t GetDataStart(void) const { return m_DataStart; }
/// Returns true if the specified amount of bytes are available for reading
bool CanReadBytes(size_t a_Count) const;
/// Returns true if the specified amount of bytes are available for writing
bool CanWriteBytes(size_t a_Count) const;
// Read the specified datatype and advance the read pointer; return true if successfully read:
bool ReadChar (char & a_Value);
bool ReadByte (unsigned char & a_Value);
bool ReadBEShort (short & a_Value);
bool ReadBEInt (int & a_Value);
bool ReadBEInt64 (Int64 & a_Value);
bool ReadBEFloat (float & a_Value);
bool ReadBEDouble (double & a_Value);
bool ReadBool (bool & a_Value);
bool ReadBEUTF16String16(AString & a_Value); // string length as BE short, then string as UTF-16BE
bool ReadVarInt (UInt32 & a_Value);
bool ReadVarUTF8String (AString & a_Value); // string length as VarInt, then string as UTF-8
bool ReadLEInt (int & a_Value);
/// Reads VarInt, assigns it to anything that can be assigned from an UInt32 (unsigned short, char, Byte, double, ...)
template <typename T> bool ReadVarInt(T & a_Value)
{
UInt32 v;
bool res = ReadVarInt(v);
if (res)
{
a_Value = v;
}
return res;
}
// Write the specified datatype; return true if successfully written
bool WriteChar (char a_Value);
bool WriteByte (unsigned char a_Value);
bool WriteBEShort (short a_Value);
bool WriteBEInt (int a_Value);
bool WriteBEInt64 (Int64 a_Value);
bool WriteBEFloat (float a_Value);
bool WriteBEDouble (double a_Value);
bool WriteBool (bool a_Value);
bool WriteBEUTF16String16(const AString & a_Value); // string length as BE short, then string as UTF-16BE
bool WriteVarInt (UInt32 a_Value);
bool WriteVarUTF8String (const AString & a_Value); // string length as VarInt, then string as UTF-8
bool WriteLEInt (int a_Value);
/// Reads a_Count bytes into a_Buffer; returns true if successful
bool ReadBuf(void * a_Buffer, size_t a_Count);
/// Writes a_Count bytes into a_Buffer; returns true if successful
bool WriteBuf(const void * a_Buffer, size_t a_Count);
/// Reads a_Count bytes into a_String; returns true if successful
bool ReadString(AString & a_String, size_t a_Count);
/// Reads 2 * a_NumChars bytes and interprets it as a UTF16-BE string, converting it into UTF8 string a_String
bool ReadUTF16String(AString & a_String, int a_NumChars);
/// Skips reading by a_Count bytes; returns false if not enough bytes in the ringbuffer
bool SkipRead(size_t a_Count);
/// Reads all available data into a_Data
void ReadAll(AString & a_Data);
/// Reads the specified number of bytes and writes it into the destinatio bytebuffer. Returns true on success.
bool ReadToByteBuffer(cByteBuffer & a_Dst, size_t a_NumBytes);
/// Removes the bytes that have been read from the ringbuffer
void CommitRead(void);
/// Restarts next reading operation at the start of the ringbuffer
void ResetRead(void);
/// Re-reads the data that has been read since the last commit to the current readpos. Used by ProtoProxy to duplicate communication
void ReadAgain(AString & a_Out);
/// Checks if the internal state is valid (read and write positions in the correct bounds) using ASSERTs
void CheckValid(void) const;
protected:
char * m_Buffer;
size_t m_BufferSize; // Total size of the ringbuffer
#ifdef _DEBUG
volatile unsigned long m_ThreadID; // Thread that is currently accessing the object, checked via cSingleThreadAccessChecker
#endif // _DEBUG
size_t m_DataStart; // Where the data starts in the ringbuffer
size_t m_WritePos; // Where the data ends in the ringbuffer
size_t m_ReadPos; // Where the next read will start in the ringbuffer
/// Advances the m_ReadPos by a_Count bytes
void AdvanceReadPos(size_t a_Count);
} ;
