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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. /**
  30.  * @file    condvar.c
  31.  * @brief   Condition variables.
  32.  */
  33.  
  34. #include <synch/condvar.h>
  35. #include <synch/mutex.h>
  36. #include <synch/waitq.h>
  37. #include <synch/synch.h>
  38. #include <arch.h>
  39. #include <typedefs.h>
  40.  
  41. /** Initialize condition variable.
  42.  *
  43.  * @param cv Condition variable.
  44.  */
  45. void condvar_initialize(condvar_t *cv)
  46. {
  47.     waitq_initialize(&cv->wq);
  48. }
  49.  
  50. /**
  51.  * Signal the condition has become true
  52.  * to the first waiting thread by waking it up.
  53.  *
  54.  * @param cv Condition variable.
  55.  */
  56. void condvar_signal(condvar_t *cv)
  57. {
  58.     waitq_wakeup(&cv->wq, WAKEUP_FIRST);
  59. }
  60.  
  61. /**
  62.  * Signal the condition has become true
  63.  * to all waiting threads by waking them up.
  64.  *
  65.  * @param cv Condition variable.
  66.  */
  67. void condvar_broadcast(condvar_t *cv)
  68. {
  69.     waitq_wakeup(&cv->wq, WAKEUP_ALL);
  70. }
  71.  
  72. /** Wait for the condition becoming true.
  73.  *
  74.  * @param cv Condition variable.
  75.  * @param mtx Mutex.
  76.  * @param usec Timeout value in microseconds.
  77.  * @param flags Select mode of operation.
  78.  *
  79.  * For exact description of meaning of possible combinations
  80.  * of usec and flags, see comment for waitq_sleep_timeout().
  81.  * Note that when SYNCH_FLAGS_NON_BLOCKING is specified here,
  82.  * ESYNCH_WOULD_BLOCK is always returned.
  83.  *
  84.  * @return See comment for waitq_sleep_timeout().
  85.  */
  86. int _condvar_wait_timeout(condvar_t *cv, mutex_t *mtx, __u32 usec, int flags)
  87. {
  88.     int rc;
  89.     ipl_t ipl;
  90.  
  91.     ipl = waitq_sleep_prepare(&cv->wq);
  92.     mutex_unlock(mtx);
  93.  
  94.     cv->wq.missed_wakeups = 0;  /* Enforce blocking. */
  95.     rc = waitq_sleep_timeout_unsafe(&cv->wq, usec, flags);
  96.  
  97.     mutex_lock(mtx);
  98.     waitq_sleep_finish(&cv->wq, rc, ipl);
  99.  
  100.     return rc;
  101. }
  102.