buffer.h

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#define  BASE_BUFFER_SIZE	1024
#define  BASE_BUFFER_INC	512

class CAutoBuffer
{
protected:
	char *buffer;							// Yeah, this is our buffer
	int nLength;							// Current length of data
	int nSize;								// Current size of buffer
	int nIncrement;							// By how much we should increment
	// when buffer is too small

	/*
	The IncreaseSize(..) function re-allocates memory space for the
	buffer and copies its current contents into the new memory space.
	*/
	__forceinline void IncreaseSize(int nIncrement_)
	{
		char *newbuf;

		newbuf = new char [nSize + nIncrement_];
		memcpy(newbuf, buffer, nSize);

		delete [] buffer;
		buffer = newbuf;
		nSize += nIncrement_;
	}

	__forceinline void IncreaseSize()
	{
		IncreaseSize(nIncrement);
	}

public:
	CAutoBuffer(int nIncrement_) : buffer(NULL),
		nLength(0),
		nIncrement(nIncrement_)
	{
		buffer = new char [BASE_BUFFER_SIZE];	// Allocate memory
		nSize = BASE_BUFFER_SIZE;
	}

	~CAutoBuffer()
	{
		if (buffer)
			delete [] buffer;					// De-allocate memory
	}

	__forceinline int GetLength(){return nLength;}
	/*
	I assume that memory can be allocated, and that the new keyword
	never returns NULL. I didn't embed error-detection in order to
	enhance performance. If there is not enough memory to be allocated,
	something is terribly wrong.

	Furthermore, no internal memory checks are performed inside the
	functions.
	*/

	/*
	AddToBuffer(..) adds data from a source buffer to the class' buffer.
	src: the source buffer
	len: the source buffer's size
	*/
	__forceinline void AddToBuffer(const char *src, int len)
	{
		if (len > 0)
		{
			if (len + nLength > nSize)
				IncreaseSize(BASE_BUFFER_INC > len ? BASE_BUFFER_INC : len);

			memcpy(buffer + nLength, src, len);
			nLength += len;
		}
	}

	/*
	AddToBufferBeg(..) adds data from a source buffer to the beginning
	of the class' buffer.
	*/
	__forceinline void AddToBufferBeg(const char *src, int len)
	{
		if (len + nLength > nSize)
			IncreaseSize(len);

		memmove(buffer + len, buffer, nLength);
		memcpy(buffer, src, len);
		nLength += len;
	}

	/*
	GetBuffer(..) copies data from the class' buffer to a destination
	buffer. dst is a pointer to the destination buffer. len is a pointer
	to an integer that specifies the size of dst. The value to which len
	points is changes by the function, to reflect the number of bytes
	transferred from the class' buffer to the destination buffer.
	*/
	__forceinline void GetBuffer(char *dst, int start, int len)
	{
		if (nLength > (start+len))
		{	// Supplied buffer is not large enough.
			GetFromBuffer(dst,start, len);
		}
		else if (nLength > start)
		{
			memcpy(dst, buffer+start, nLength);
			len = nLength-start;
			//nLength = 0;		// Clear buffer;
		}
	}

	__forceinline void GetFromBuffer(char *dst,int start, int len)
	{
		if ((len+start) > nLength)GetBuffer(dst, start,len);
		else memcpy(dst, buffer+start, len);
	}

	__forceinline char *GetBuffer()
	{
		return buffer;
	}

	__forceinline bool IsEmpty()
	{
		return (nLength == 0);
	}

	__forceinline void ReSet(){
		if (buffer)
			delete [] buffer;
		buffer = new char [BASE_BUFFER_SIZE];	// Allocate memory
		nSize = BASE_BUFFER_SIZE;
		nLength = 0;
	}

};