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glibc  2.9
sem_trywait.c
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00001 /* sem_trywait -- wait on a semaphore.  SPARC version.
00002    Copyright (C) 2003, 2006, 2007 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004    Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
00005 
00006    The GNU C Library is free software; you can redistribute it and/or
00007    modify it under the terms of the GNU Lesser General Public
00008    License as published by the Free Software Foundation; either
00009    version 2.1 of the License, or (at your option) any later version.
00010 
00011    The GNU C Library is distributed in the hope that it will be useful,
00012    but WITHOUT ANY WARRANTY; without even the implied warranty of
00013    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00014    Lesser General Public License for more details.
00015 
00016    You should have received a copy of the GNU Lesser General Public
00017    License along with the GNU C Library; if not, write to the Free
00018    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
00019    02111-1307 USA.  */
00020 
00021 #include <errno.h>
00022 #include <sysdep.h>
00023 #include <lowlevellock.h>
00024 #include <internaltypes.h>
00025 #include <semaphore.h>
00026 
00027 #include <shlib-compat.h>
00028 
00029 
00030 int
00031 __new_sem_trywait (sem_t *sem)
00032 {
00033   struct sparc_old_sem *isem = (struct sparc_old_sem *) sem;
00034   int val;
00035 
00036   if (isem->value > 0)
00037     {
00038       if (__atomic_is_v9)
00039        val = atomic_decrement_if_positive (&isem->value);
00040       else
00041        {
00042          __sparc32_atomic_do_lock24 (&isem->lock);
00043          val = isem->value;
00044          if (val > 0)
00045            isem->value = val - 1;
00046          __sparc32_atomic_do_unlock24 (&isem->lock);
00047        }
00048       if (val > 0)
00049        return 0;
00050     }
00051 
00052   __set_errno (EAGAIN);
00053   return -1;
00054 }
00055 versioned_symbol (libpthread, __new_sem_trywait, sem_trywait, GLIBC_2_1);
00056 #if SHLIB_COMPAT (libpthread, GLIBC_2_0, GLIBC_2_1)
00057 strong_alias (__new_sem_trywait, __old_sem_trywait)
00058 compat_symbol (libpthread, __old_sem_trywait, sem_trywait, GLIBC_2_0);
00059 #endif