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/*
* Video On Demand Samples
*
* Copyright (C) 2015 Microchip Technology Germany II GmbH & Co. KG
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
* You may also obtain this software under a propriety license from Microchip.
* Please contact Microchip for further information.
*
*/
/*----------------------------------------------------------*/
/*! \file
* \brief This file contains the CRingBuffer class.
*/
/*----------------------------------------------------------*/
#ifndef CRINGBUFFER_H
#define CRINGBUFFER_H
#include "Console.h"
/*----------------------------------------------------------*/
/*! \brief Class providing a ring buffer. One thread can
* write to the buffer while another thread is reading
* from it. This class has highest performance for
* synchronization, since it is not using mutexes.
*
* LIMITATIONS:
* - only one thread can read
* - only one thread can write
* - the ring buffer size needs to be aligned to
* read, write block size
*
* Violating any limitation will lead to unpredictable
* results.
*/
/*----------------------------------------------------------*/
class CRingBuffer
{
uint8_t *m_pBuf;
uint32_t m_nWriteTot; // total bytes written to ring buffer
uint32_t m_nReadTot; // total bytes read from ring buffer
uint32_t m_nWritePos; // memory write position
uint32_t m_nReadPos; // memory read position
uint32_t m_nReadLen; // bytes per read
uint32_t m_nWriteLen; // bytes per write
uint32_t m_nBufLen; // bytes of buffer
public:
/*----------------------------------------------------------*/
/*! \brief constructs a ring buffer instance
* \param nReadLen - read block size in bytes
* \param nWriteLen - write block size in bytes
* \param nWriteBlocks - total buffer size counted in write
* blocks
*/
/*----------------------------------------------------------*/
CRingBuffer(uint32_t nReadLen, uint32_t nWriteLen, uint32_t nWriteBlocks)
: m_nWriteTot(0)
, m_nReadTot(0)
, m_nWritePos(0)
, m_nReadPos(0)
, m_nReadLen(nReadLen)
, m_nWriteLen(nWriteLen)
, m_nBufLen(nWriteBlocks*nWriteLen)
{
if ( 0 != (m_nBufLen % m_nReadLen) ) {
ConsolePrintf( PRIO_ERROR, RED"! ring size needs to be dividable by read block size"RESETCOLOR);
throw (-10);
}
m_pBuf = new uint8_t[m_nBufLen];
if (NULL == m_pBuf) {
ConsolePrintf( PRIO_ERROR, RED"! out of memory"RESETCOLOR);
throw (-10);
}
}
/*----------------------------------------------------------*/
/*! \brief destructs ring buffer instance
*/
/*----------------------------------------------------------*/
~CRingBuffer()
{
delete m_pBuf;
}
/*----------------------------------------------------------*/
/*! \brief checks if there is enough memory available to
* write a chunk of data to the ring buffer
* \return true, if can be written
*/
/*----------------------------------------------------------*/
bool GetCanWrite()
{
uint32_t nFilled = m_nWriteTot - m_nReadTot;
return nFilled < m_nBufLen - m_nWriteLen;
}
/*----------------------------------------------------------*/
/*! \brief checks if there is enough memory available to
* read a chunk of data from the ring buffer
* \return true, if can be read
*/
/*----------------------------------------------------------*/
bool GetCanRead()
{
uint32_t nFilled = m_nWriteTot - m_nReadTot;
return nFilled >= m_nReadLen;
}
/*----------------------------------------------------------*/
/*! \brief gets pointer to current read position
* \return pointer to current read position
*/
/*----------------------------------------------------------*/
uint8_t *GetReadPos()
{
return m_pBuf + m_nReadPos;
}
/*----------------------------------------------------------*/
/*! \brief gets pointer to current write position
* \return pointer to current write position
*/
/*----------------------------------------------------------*/
uint8_t *GetWritePos()
{
return m_pBuf + m_nWritePos;
}
/*----------------------------------------------------------*/
/*! \brief called after a chunk of data has been written
* to the ring buffer
*/
/*----------------------------------------------------------*/
void WriteDone()
{
m_nWriteTot += m_nWriteLen;
m_nWritePos += m_nWriteLen;
if (m_nBufLen == m_nWritePos)
m_nWritePos = 0;
}
/*----------------------------------------------------------*/
/*! \brief called after a chunk of data has been read
* from the ring buffer
*/
/*----------------------------------------------------------*/
void ReadDone()
{
m_nReadTot += m_nReadLen;
m_nReadPos += m_nReadLen;
if (m_nBufLen == m_nReadPos)
m_nReadPos = 0;
}
};
#endif
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