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  1. /*
  2.  * Copyright (c) 2008 Jakub Jermar
  3.  * All rights reserved.
  4.  *
  5.  * Redistribution and use in source and binary forms, with or without
  6.  * modification, are permitted provided that the following conditions
  7.  * are met:
  8.  *
  9.  * - Redistributions of source code must retain the above copyright
  10.  *   notice, this list of conditions and the following disclaimer.
  11.  * - Redistributions in binary form must reproduce the above copyright
  12.  *   notice, this list of conditions and the following disclaimer in the
  13.  *   documentation and/or other materials provided with the distribution.
  14.  * - The name of the author may not be used to endorse or promote products
  15.  *   derived from this software without specific prior written permission.
  16.  *
  17.  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
  18.  * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
  19.  * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
  20.  * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
  21.  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
  22.  * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  23.  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  24.  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  25.  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
  26.  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  27.  */
  28.  
  29. /** @addtogroup libc
  30.  * @{
  31.  */
  32. /**
  33.  * @file
  34.  * @brief   This file contains rwlock API and provides its fake
  35.  *      implementation based on futexes.
  36.  */
  37.  
  38. #ifndef LIBC_RWLOCK_H_
  39. #define LIBC_RWLOCK_H_
  40.  
  41. #include <atomic.h>
  42. #include <sys/types.h>
  43. #include <futex.h>
  44.  
  45. typedef atomic_t rwlock_t;
  46.  
  47. #define RWLOCK_INITIALIZE(rwlock)   \
  48.     rwlock_t rwlock = FUTEX_INITIALIZER
  49.  
  50. #define rwlock_initialize(rwlock)   futex_initialize((rwlock), 1)
  51. #define rwlock_read_lock(rwlock)    futex_down((rwlock))
  52. #define rwlock_write_lock(rwlock)   futex_down((rwlock))
  53. #define rwlock_read_unlock(rwlock)  futex_up((rwlock))
  54. #define rwlock_write_unlock(rwlock) futex_up((rwlock))
  55.  
  56. #endif
  57.  
  58. /** @}
  59.  */
  60.