/*
 *  TAP-Windows -- 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) 2002-2014 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;                                             \
      }                                                    \
    }                                                      \
  }
