C++环形缓冲区

https://blog.csdn.net/weiyu00/article/details/84750560

#pragma once

template <class T> 
class CRingBuffer
{
public:
	CRingBuffer()
	{
		m_pBuffer = NULL;
		m_nSize = 0;
		m_nUnreadSize = 0;
		m_nWritePos = 0;
		m_nReadPos = 0;
	}

	virtual ~CRingBuffer()
	{
		m_cs.Lock();
		if (m_pBuffer != NULL)
		{
			delete [] m_pBuffer;
			m_pBuffer = NULL;
			m_nSize = 0;
			m_nUnreadSize = 0;
			m_nWritePos = 0;
			m_nReadPos = 0;
		}
		m_cs.Unlock();
	}

	//清空环形缓冲区
	void Clear()
	{
		m_cs.Lock();
		m_nUnreadSize = 0;
		m_nWritePos = 0;
		m_nReadPos = 0;
		m_cs.Unlock();
	}

	//设置环形缓冲区
	//nSize：缓冲区大小
	void SetBuffer(int nSize)
	{
		m_cs.Lock();
		if (m_pBuffer != NULL)
		{
			delete [] m_pBuffer;
			m_pBuffer = NULL;
			m_nSize = 0;
			m_nUnreadSize = 0;
			m_nWritePos = 0;
			m_nReadPos = 0;
		}

		m_pBuffer = new T[nSize];
		if (m_pBuffer != NULL)
		{
			memset(m_pBuffer, 0x00, nSize*sizeof(T));
			m_nSize = nSize;
			m_nUnreadSize = 0;
			m_nWritePos = 0;
			m_nReadPos = 0;
		}
		m_cs.Unlock();
	}
	//写入数据到环形缓冲区
	//返回值：写入的数据大小
	int WriteData(const T* pT, int nSize = 1)
	{
		m_cs.Lock();
		if (nSize > m_nSize - m_nUnreadSize)//缓冲区大小不足时，仅写入最前面的数据
			nSize = m_nSize - m_nUnreadSize;

		if (nSize > 0)
		{
			if (m_nWritePos + nSize <= m_nSize)
			{
				memcpy(&m_pBuffer[m_nWritePos], pT, nSize*sizeof(T));
			}
			else
			{
				memcpy(&m_pBuffer[m_nWritePos], pT, (m_nSize - m_nWritePos)*sizeof(T));
				if (nSize - (m_nSize - m_nWritePos) > 0)
					memcpy(m_pBuffer, &pT[m_nSize - m_nWritePos], (nSize - (m_nSize - m_nWritePos))*sizeof(T));
			}

			m_nUnreadSize += nSize;
			m_nWritePos += nSize;
			if (m_nWritePos >= m_nSize)
				m_nWritePos %= m_nSize;
		}

		m_cs.Unlock();
		return nSize;
	}
	//从环形缓冲区读取数据
	//nSize：缓冲区大小
	//返回值：读取的数据大小
	int ReadData(T* pT, int nSize = 1)
	{
		m_cs.Lock();
		if (nSize > m_nUnreadSize || m_nUnreadSize == 0)
			nSize = m_nUnreadSize;

		if (nSize > 0)
		{
			if (m_nReadPos + nSize <= m_nSize)
			{
				memcpy(pT, &m_pBuffer[m_nReadPos], nSize*sizeof(T));
			}
			else
			{
				memcpy(pT, &m_pBuffer[m_nReadPos], (m_nSize - m_nReadPos)*sizeof(T));
				if (nSize - (m_nSize - m_nReadPos) > 0)
					memcpy(&pT[m_nSize - m_nReadPos], m_pBuffer, (nSize - (m_nSize - m_nReadPos))*sizeof(T));
			}

			m_nUnreadSize -= nSize;
			m_nReadPos += nSize;
			if (m_nReadPos >= m_nSize)
				m_nReadPos %= m_nSize;
		}

		m_cs.Unlock();
		return nSize;
	}
private:
	T* m_pBuffer;	//缓冲区
	int m_nSize;	//缓冲区大小

	int m_nUnreadSize;	//未读取的数据大小

	int m_nWritePos;		//写入下标
	int m_nReadPos;			//读取下标

	CComAutoCriticalSection m_cs;//线程锁
};