System.Runtime.InteropServices.GCHandle.ToIntPtr C# (CSharp) Method

        public static IntPtr ToIntPtr(GCHandle value)
        {
            return value.m_handle;
        }       

      ///
      /// Returns the next header we should write to, or blocks until
      /// one is available. The returned header is done and prepared.
      ///
      void _GetFreeHeader( out GCHandle nextIntPtr,
                           out WAVEHDR nextAsHeader )
      {
         while (true)
         {
            // Clear the wave event before checking "done" to 
            // reduce the race condition between checking and 
            // waiting on the event. (it's manual reset...)
            _playEvent.Reset();

            // Note that the header memory fields will be updated
            // by the wave engine at the same time. Oooh, scary!
            // OK, so we're just checking one bit in an int, it's not
            // really dangerous.

            nextFree = _waveHdr[_nextFreeHeader];
            nextAsHeader = (WAVEHDR)nextFree.Target;
            nextIntPtr = nextIntPtr.ToIntPtr();

            if (nextAsHeader.dwFlags & WHDR_DONE)
            {
               if (nextAsHeader.dwFlags & WHDR_PREPARED)
               {
                  int status = waveOutUnprepareHeader
                     ( _waveOutHandle,
                       nextIntPtr,
                       Marshal.sizeof(typeof(WAVEHDR)) );
                  
                  if (status != MMSYSERR_NOERROR)
                  {
                     // Ugh? Still playing? But WHDR_DONE is set!
                     throw new ApplicationException( 
                        String.Format( "Error '{0}' unpreparing wave header",
                                       status ) 
                        );
                  }
               }

               // Switch buffers. Whee.
               _nextFreeHeader = _nextFreeHeader ^ 0x01;
               return;
            }

            // The next buffer is not done. Wait for it to be done.
            // Note there is a race condition here. :(
            _playEvent.WaitOne( 500, false );

            // Could check here to avoid non-buffer-done type events,
            // but really it doesn't matter.
         }
      }