Overworked Message Handler class and a simple Get-Set DSP class http://www.eventhelix.com/realtimemantra/object_oriented/object_design_tips_2.htm

overworked-message-handler.cpp

class DSP
{
public:
   Queue *GetWriteBufferQueue();
   Queue *GetReadBufferQueue();

   void SetStatusRegister(int mask);
   void SetCongestionLevel();
   
   void SetWriteBufferQueue(Buffer *pQueue);
   void SetReadBufferQueue(Buffer *pQueue);   
};   

Status MessageHandler::SendMessage(Buffer *pBuffer)
{
    int dspId = pBuffer->GetDSP();
    DSP* pDSP = m_dsp[dspId];
    Queue *pQueue = pDSP->GetWriteBufferQueue();
    
    int status = pQueue->Add(pBuffer);    
    pDSP->SetStatusRegister(WRITTEN_MESSAGE);
    
    if (pQueue->GetLength() > CONGESTION_THRESHOLD)
    {
       pDSP->SetCongestionLevel();
    }
    return status;
}