native_client_sdk/src/libraries/third_party/pthreads-win32/sem_post_multiple.c

   1 /*
   2  * -------------------------------------------------------------
   3  *
   4  * Module: sem_post_multiple.c
   5  *
   6  * Purpose:
   7  *      Semaphores aren't actually part of the PThreads standard.
   8  *      They are defined by the POSIX Standard:
   9  *
  10  *              POSIX 1003.1b-1993      (POSIX.1b)
  11  *
  12  * -------------------------------------------------------------
  13  *
  14  * --------------------------------------------------------------------------
  15  *
  16  *      Pthreads-win32 - POSIX Threads Library for Win32
  17  *      Copyright(C) 1998 John E. Bossom
  18  *      Copyright(C) 1999,2005 Pthreads-win32 contributors
  19  *
  20  *      Contact Email: rpj@callisto.canberra.edu.au
  21  *
  22  *      The current list of contributors is contained
  23  *      in the file CONTRIBUTORS included with the source
  24  *      code distribution. The list can also be seen at the
  25  *      following World Wide Web location:
  26  *      http://sources.redhat.com/pthreads-win32/contributors.html
  27  *
  28  *      This library is free software; you can redistribute it and/or
  29  *      modify it under the terms of the GNU Lesser General Public
  30  *      License as published by the Free Software Foundation; either
  31  *      version 2 of the License, or (at your option) any later version.
  32  *
  33  *      This library is distributed in the hope that it will be useful,
  34  *      but WITHOUT ANY WARRANTY; without even the implied warranty of
  35  *      MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  36  *      Lesser General Public License for more details.
  37  *
  38  *      You should have received a copy of the GNU Lesser General Public
  39  *      License along with this library in the file COPYING.LIB;
  40  *      if not, write to the Free Software Foundation, Inc.,
  41  *      59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
  42  */
  43
  44 #include "pthread.h"
  45 #include "semaphore.h"
  46 #include "implement.h"
  47
  48
  49 int
  50 sem_post_multiple (sem_t * sem, int count)
  51      /*
  52       * ------------------------------------------------------
  53       * DOCPUBLIC
  54       *      This function posts multiple wakeups to a semaphore.
  55       *
  56       * PARAMETERS
  57       *      sem
  58       *              pointer to an instance of sem_t
  59       *
  60       *      count
  61       *              counter, must be greater than zero.
  62       *
  63       * DESCRIPTION
  64       *      This function posts multiple wakeups to a semaphore. If there
  65       *      are waiting threads (or processes), n <= count are awakened;
  66       *      the semaphore value is incremented by count - n.
  67       *
  68       * RESULTS
  69       *              0               successfully posted semaphore,
  70       *              -1              failed, error in errno
  71       * ERRNO
  72       *              EINVAL          'sem' is not a valid semaphore
  73       *                              or count is less than or equal to zero.
  74       *              ERANGE          semaphore count is too big
  75       *
  76       * ------------------------------------------------------
  77       */
  78 {
  79   int result = 0;
  80   long waiters;
  81   sem_t s = *sem;
  82
  83   if (s == NULL || count <= 0)
  84     {
  85       result = EINVAL;
  86     }
  87   else if ((result = pthread_mutex_lock (&s->lock)) == 0)
  88     {
  89       /* See sem_destroy.c
  90        */
  91       if (*sem == NULL)
  92         {
  93           (void) pthread_mutex_unlock (&s->lock);
  94           result = EINVAL;
  95           return -1;
  96         }
  97
  98       if (s->value <= (SEM_VALUE_MAX - count))
  99         {
 100           waiters = -s->value;
 101           s->value += count;
 102           if (waiters > 0)
 103             {
 104 #if defined(NEED_SEM)
 105               if (SetEvent(s->sem))
 106                 {
 107                   waiters--;
 108                   s->leftToUnblock += count - 1;
 109                   if (s->leftToUnblock > waiters)
 110                     {
 111                       s->leftToUnblock = waiters;
 112                     }
 113                 }
 114 #else
 115               if (ReleaseSemaphore (s->sem,  (waiters<=count)?waiters:count, 0))
 116                 {
 117                   /* No action */
 118                 }
 119 #endif
 120               else
 121                 {
 122                   s->value -= count;
 123                   result = EINVAL;
 124                 }
 125             }
 126         }
 127       else
 128         {
 129           result = ERANGE;
 130         }
 131       (void) pthread_mutex_unlock (&s->lock);
 132     }
 133
 134   if (result != 0)
 135     {
 136       errno = result;
 137       return -1;
 138     }
 139
 140   return 0;
 141
 142 }                               /* sem_post_multiple */