/*

  *  TAP-Win32/TAP-Win64 -- A kernel driver to provide virtual tap
  *                         device functionality on Windows.

  *

  *  This code was inspired by the CIPE-Win32 driver by Damion K. Wilson.

  *

  *  This source code is Copyright (C) 2002-2010 OpenVPN Technologies, Inc.,

  *  and is released under the GPL version 2 (see below).

  *
  *  This program is free software; you can redistribute it and/or modify
  *  it under the terms of the GNU General Public License version 2
  *  as published by the Free Software Foundation.
  *
  *  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 (see the file COPYING included with this
  *  distribution); if not, write to the Free Software Foundation, Inc.,
  *  59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  */
 
 typedef struct
 {
   volatile long count;
 } MUTEX;
 
 #define MUTEX_SLEEP_TIME  10000 // microseconds
 
 #define INIT_MUTEX(m) { (m)->count = 0; }
 
 #define ACQUIRE_MUTEX_BLOCKING(m)                         \
 {                                                         \
     while (NdisInterlockedIncrement (&((m)->count)) != 1) \
     {                                                     \
         NdisInterlockedDecrement(&((m)->count));          \
         NdisMSleep(MUTEX_SLEEP_TIME);                     \
     }                                                     \
 }
 
 #define RELEASE_MUTEX(m)                                  \
 {                                                         \
         NdisInterlockedDecrement(&((m)->count));          \
 }
 
 #define ACQUIRE_MUTEX_NONBLOCKING(m, result)              \
 {                                                         \
     if (NdisInterlockedIncrement (&((m)->count)) != 1)    \
     {                                                     \
         NdisInterlockedDecrement(&((m)->count));          \
         result = FALSE;                                   \
     }                                                     \
     else                                                  \
     {                                                     \
 	result = TRUE;                                    \
     }                                                     \
 }
 
 #define ACQUIRE_MUTEX_ADAPTIVE(m, result)                 \
 {                                                         \
     result = TRUE;                                        \
     while (NdisInterlockedIncrement (&((m)->count)) != 1) \
     {                                                     \
         NdisInterlockedDecrement(&((m)->count));          \
         if (KeGetCurrentIrql () < DISPATCH_LEVEL)         \
             NdisMSleep(MUTEX_SLEEP_TIME);                 \
         else                                              \
         {                                                 \
 	    result = FALSE;                               \
 	    break;                                        \
         }                                                 \
     }                                                     \
 }