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  1. /*
  2.  * Copyright (c) 2001-2004 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 sync
  30.  * @{
  31.  */
  32.  
  33. /**
  34.  * @file
  35.  * @brief   Condition variables.
  36.  */
  37.  
  38. #include <synch/condvar.h>
  39. #include <synch/mutex.h>
  40. #include <synch/waitq.h>
  41. #include <synch/synch.h>
  42. #include <arch.h>
  43.  
  44. /** Initialize condition variable.
  45.  *
  46.  * @param cv        Condition variable.
  47.  */
  48. void condvar_initialize(condvar_t *cv)
  49. {
  50.     waitq_initialize(&cv->wq);
  51. }
  52.  
  53. /** Signal the condition has become true to the first waiting thread by waking
  54.  * it up.
  55.  *
  56.  * @param cv        Condition variable.
  57.  */
  58. void condvar_signal(condvar_t *cv)
  59. {
  60.     waitq_wakeup(&cv->wq, WAKEUP_FIRST);
  61. }
  62.  
  63. /** Signal the condition has become true to all waiting threads by waking
  64.  * them up.
  65.  *
  66.  * @param cv        Condition variable.
  67.  */
  68. void condvar_broadcast(condvar_t *cv)
  69. {
  70.     waitq_wakeup(&cv->wq, WAKEUP_ALL);
  71. }
  72.  
  73. /** Wait for the condition becoming true.
  74.  *
  75.  * @param cv        Condition variable.
  76.  * @param mtx       Mutex.
  77.  * @param usec      Timeout value in microseconds.
  78.  * @param flags     Select mode of operation.
  79.  *
  80.  * For exact description of meaning of possible combinations of usec and flags,
  81.  * see comment for waitq_sleep_timeout().  Note that when
  82.  * SYNCH_FLAGS_NON_BLOCKING is specified here, ESYNCH_WOULD_BLOCK is always
  83.  * returned.
  84.  *
  85.  * @return      See comment for waitq_sleep_timeout().
  86.  */
  87. int _condvar_wait_timeout(condvar_t *cv, mutex_t *mtx, uint32_t usec, int flags)
  88. {
  89.     int rc;
  90.     ipl_t ipl;
  91.  
  92.     ipl = waitq_sleep_prepare(&cv->wq);
  93.     mutex_unlock(mtx);
  94.  
  95.     cv->wq.missed_wakeups = 0;  /* Enforce blocking. */
  96.     rc = waitq_sleep_timeout_unsafe(&cv->wq, usec, flags);
  97.  
  98.     mutex_lock(mtx);
  99.     waitq_sleep_finish(&cv->wq, rc, ipl);
  100.  
  101.     return rc;
  102. }
  103.  
  104. /** @}
  105.  */
  106.