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glibc  2.9
pspinlock.c
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00001 /* POSIX spinlock implementation.  SH version.
00002    Copyright (C) 2000, 2001 Free Software Foundation, Inc.
00003    This file is part of the GNU C Library.
00004 
00005    The GNU C Library is free software; you can redistribute it and/or
00006    modify it under the terms of the GNU Lesser General Public License as
00007    published by the Free Software Foundation; either version 2.1 of the
00008    License, or (at your option) any later version.
00009 
00010    The GNU C Library is distributed in the hope that it will be useful,
00011    but WITHOUT ANY WARRANTY; without even the implied warranty of
00012    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
00013    Lesser General Public License for more details.
00014 
00015    You should have received a copy of the GNU Lesser General Public
00016    License along with the GNU C Library; see the file COPYING.LIB.  If not,
00017    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
00018    Boston, MA 02111-1307, USA.  */
00019 
00020 #include <errno.h>
00021 #include <pthread.h>
00022 #include "internals.h"
00023 
00024 int
00025 __pthread_spin_lock (pthread_spinlock_t *lock)
00026 {
00027   unsigned int val;
00028 
00029   do
00030     asm volatile ("tas.b @%1; movt %0"
00031                 : "=r" (val)
00032                 : "r" (lock)
00033                 : "memory");
00034   while (val == 0);
00035 
00036   return 0;
00037 }
00038 weak_alias (__pthread_spin_lock, pthread_spin_lock)
00039 
00040 
00041 int
00042 __pthread_spin_trylock (pthread_spinlock_t *lock)
00043 {
00044   unsigned int val;
00045 
00046   asm volatile ("tas.b @%1; movt %0"
00047               : "=r" (val)
00048               : "r" (lock)
00049               : "memory");
00050   return val ? 0 : EBUSY;
00051 }
00052 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
00053 
00054 
00055 int
00056 __pthread_spin_unlock (pthread_spinlock_t *lock)
00057 {
00058   return *lock = 0;
00059 }
00060 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
00061 
00062 
00063 int
00064 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
00065 {
00066   /* We can ignore the `pshared' parameter.  Since we are busy-waiting
00067      all processes which can access the memory location `lock' points
00068      to can use the spinlock.  */
00069   return *lock = 0;
00070 }
00071 weak_alias (__pthread_spin_init, pthread_spin_init)
00072 
00073 
00074 int
00075 __pthread_spin_destroy (pthread_spinlock_t *lock)
00076 {
00077   /* Nothing to do.  */
00078   return 0;
00079 }
00080 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)