text: 
  // Copyright (c) 2018 brinkqiang
  //
  // Permission is hereby granted, free of charge, to any person obtaining a copy
  // of this software and associated documentation files (the "Software"), to deal
  // in the Software without restriction, including without limitation the rights
  // to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  // copies of the Software, and to permit persons to whom the Software is
  // furnished to do so, subject to the following conditions:
  //
  // The above copyright notice and this permission notice shall be included in all
  // copies or substantial portions of the Software.
  //
  // THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  // IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  // FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  // AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  // LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  // OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  // SOFTWARE.
  
  
  #ifndef __DMQUEUE_H_INCLUDE__
  #define __DMQUEUE_H_INCLUDE__
  
  #include <stddef.h>
  
  class CDMQueue {
    public:
      CDMQueue( void )
          : m_pArray( NULL ), m_nHead( 0 ), m_nTail( 0 ), m_nSize( 0 ) {
      }
  
      ~CDMQueue( void ) {
          delete []m_pArray;
          m_nHead = 0;
          m_nTail = 0;
          m_nSize = 0;
      }
  
      bool Init( int nSize ) {
          m_nSize = nSize + 1;
          m_pArray = new void* [m_nSize]();
          return true;
      }
  
      bool PushBack( void* ptr ) {
          int nDist = m_nTail + m_nSize - m_nHead;
          int nUsed = nDist >= m_nSize ? ( nDist - m_nSize ) : nDist;
  
          if ( nUsed >= m_nSize - 1 ) {
              return false;
          }
  
          m_pArray[m_nTail] = ptr;
  
          if ( ++m_nTail >= m_nSize ) {
              m_nTail = 0;
          }
  
          return true;
      }
  
      void* PopFront() {
          int nDist = m_nTail + m_nSize - m_nHead;
          int nUsed = nDist >= m_nSize ? ( nDist - m_nSize ) : nDist;
  
          if ( 0 == nUsed ) {
              return NULL;
          }
  
          void* ptr = m_pArray[m_nHead];
  
          if ( ++m_nHead >= m_nSize ) {
              m_nHead = 0;
          }
  
          return ptr;
      }
  
  
    protected:
      void**  m_pArray;
      int   m_nHead;
      int   m_nTail;
      int   m_nSize;
  };
  
  #endif // __DMQUEUE_H_INCLUDE__
  