AERingBuffer.h

/*
 *  Copyright (C) 2010-2018 Team Kodi
 *  This file is part of Kodi - https://kodi.tv
 *
 *  SPDX-License-Identifier: GPL-2.0-or-later
 *  See LICENSES/README.md for more information.
 */

#pragma once

#define AE_RING_BUFFER_OK 0;
#define AE_RING_BUFFER_EMPTY 1;
#define AE_RING_BUFFER_FULL 2;
#define AE_RING_BUFFER_NOTAVAILABLE 3;

//#define AE_RING_BUFFER_DEBUG

#include "utils/log.h"
#include "utils/MemUtils.h"

#include <string.h>

class AERingBuffer {

public:
  AERingBuffer() = default;

  AERingBuffer(unsigned int size, unsigned int planes = 1) { Create(size, planes); }

  ~AERingBuffer()
  {
#ifdef AE_RING_BUFFER_DEBUG
    CLog::Log(LOGDEBUG, "AERingBuffer::~AERingBuffer: Deleting buffer.");
#endif
    for (unsigned int i = 0; i < m_planes; i++)
      KODI::MEMORY::AlignedFree(m_Buffer[i]);
    delete[] m_Buffer;
  }

  bool Create(int size, unsigned int planes = 1)
  {
    m_Buffer = new unsigned char*[planes];
    for (unsigned int i = 0; i < planes; i++)
    {
      m_Buffer[i] = static_cast<unsigned char*>(KODI::MEMORY::AlignedMalloc(size, 16));
      if (!m_Buffer[i])
        return false;
      memset(m_Buffer[i], 0, size);
    }
    m_iSize = size;
    m_planes = planes;
    return true;
  }

  void Reset() {
#ifdef AE_RING_BUFFER_DEBUG
    CLog::Log(LOGDEBUG, "AERingBuffer::Reset: Buffer reset.");
#endif
    m_iWritten = 0;
    m_iRead = 0;
    m_iReadPos = 0;
    m_iWritePos = 0;
  }

  int Write(unsigned char *src, unsigned int size, unsigned int plane = 0)
  {
    unsigned int space = GetWriteSize();

    //do we have enough space for all the data?
    if (size > space || plane >= m_planes)
    {
#ifdef AE_RING_BUFFER_DEBUG
      CLog::Log(LOGDEBUG,
                "AERingBuffer: Not enough space, ignoring data. Requested: {} Available: {}", size,
                space);
#endif
      return AE_RING_BUFFER_FULL;
    }

    //no wrapping?
    if ( m_iSize > size + m_iWritePos )
    {
#ifdef AE_RING_BUFFER_DEBUG
      CLog::Log(LOGDEBUG, "AERingBuffer: Written to: {} size: {} space before: {}", m_iWritePos,
                size, space);
#endif
      memcpy(m_Buffer[plane] + m_iWritePos, src, size);
    }
    //need to wrap
    else
    {
      unsigned int first = m_iSize - m_iWritePos;
      unsigned int second = size - first;
#ifdef AE_RING_BUFFER_DEBUG
      CLog::Log(LOGDEBUG,
                "AERingBuffer: Written to (split) first: {} second: {} size: {} space before: {}",
                first, second, size, space);
#endif
      memcpy(m_Buffer[plane] + m_iWritePos, src, first);
      memcpy(m_Buffer[plane], src + first, second);
    }
    if (plane + 1 == m_planes)
      WriteFinished(size);

    return AE_RING_BUFFER_OK;
  }

  int Read(unsigned char *dest, unsigned int size, unsigned int plane = 0)
  {
    unsigned int space = GetReadSize();

    //want to read more than we have written?
    if( space == 0 )
    {
#ifdef AE_RING_BUFFER_DEBUG
      CLog::Log(LOGDEBUG, "AERingBuffer: Can't read from empty buffer.");
#endif
      return AE_RING_BUFFER_EMPTY;
    }

    //want to read more than we have available
    if( size > space || plane >= m_planes)
    {
#ifdef AE_RING_BUFFER_DEBUG
      CLog::Log(LOGDEBUG, "AERingBuffer: Can't read {} bytes when we only have {}.", size, space);
#endif
      return AE_RING_BUFFER_NOTAVAILABLE;
    }

    //no wrapping?
    if ( size + m_iReadPos < m_iSize )
    {
#ifdef AE_RING_BUFFER_DEBUG
      CLog::Log(LOGDEBUG, "AERingBuffer: Reading from: {} size: {} space before: {}", m_iWritePos,
                size, space);
#endif
      if (dest)
        memcpy(dest, m_Buffer[plane] + m_iReadPos, size);
    }
    //need to wrap
    else
    {
      unsigned int first = m_iSize - m_iReadPos;
      unsigned int second = size - first;
#ifdef AE_RING_BUFFER_DEBUG
      CLog::Log(LOGDEBUG,
                "AERingBuffer: Reading from (split) first: {} second: {} size: {} space before: {}",
                first, second, size, space);
#endif
      if (dest)
      {
        memcpy(dest, m_Buffer[plane] + m_iReadPos, first);
        memcpy(dest + first, m_Buffer[plane], second);
      }
    }
    if (plane + 1 == m_planes)
      ReadFinished(size);

    return AE_RING_BUFFER_OK;
  }

  void Dump()
  {
    unsigned char *bufferContents = static_cast<unsigned char*>(KODI::MEMORY::AlignedMalloc(m_iSize * m_planes + 1, 16));
    unsigned char *dest = bufferContents;
    for (unsigned int j = 0; j < m_planes; j++)
    {
      for (unsigned int i=0; i<m_iSize; i++)
      {
        if (i >= m_iReadPos && i<m_iWritePos)
          *dest++ = m_Buffer[j][i];
        else
          *dest++ = '_';
      }
    }
    bufferContents[m_iSize*m_planes] = '\0';
    CLog::LogF(LOGDEBUG, "Buffer Content: {}", reinterpret_cast<const char*>(bufferContents));
    KODI::MEMORY::AlignedFree(bufferContents);
  }

  unsigned int GetWriteSize()
  {
    return m_iSize - ( m_iWritten - m_iRead );
  }

  unsigned int GetReadSize()
  {
    return m_iWritten - m_iRead;
  }

  unsigned int GetMaxSize()
  {
    return m_iSize;
  }

  unsigned int NumPlanes() const
  {
    return m_planes;
  }
private:
  void WriteFinished(unsigned int size)
  {
    if ( m_iSize > size + m_iWritePos )
      m_iWritePos += size;
    else // wrapping
      m_iWritePos = size - (m_iSize - m_iWritePos);

    //we can increase the write count now
    m_iWritten+=size;
  }

  void ReadFinished(unsigned int size)
  {
    if ( size + m_iReadPos < m_iSize )
      m_iReadPos += size;
    else
      m_iReadPos = size - (m_iSize - m_iReadPos);

    //we can increase the read count now
    m_iRead+=size;
  }

  unsigned int m_iReadPos = 0;
  unsigned int m_iWritePos = 0;
  unsigned int m_iRead = 0;
  unsigned int m_iWritten = 0;
  unsigned int m_iSize = 0;
  unsigned int m_planes = 0;
  unsigned char** m_Buffer = nullptr;
};