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glibc  2.9
pspinlock.c
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00001 /* POSIX spinlock implementation.  AM33 version.
00002    Copyright 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 Library General Public License as
00007    published by the Free Software Foundation; either version 2 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    Library General Public License for more details.
00014 
00015    You should have received a copy of the GNU Library 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   __asm__ __volatile__("1: bset %1, (%0); beq 1b"
00028                      : : "a" (lock), "d" (1) : "memory");
00029   return 0;
00030 }
00031 weak_alias (__pthread_spin_lock, pthread_spin_lock)
00032 
00033 
00034 int
00035 __pthread_spin_trylock (pthread_spinlock_t *lock)
00036 {
00037   int oldval = 1;
00038 
00039   __asm__ __volatile__ ("bset %0, (%1); beq 1f; clr %0; 1:" :
00040                      "+d" (oldval) : "a" (lock) : "memory");
00041 
00042   return oldval ? EBUSY : 0;
00043 }
00044 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
00045 
00046 
00047 int
00048 __pthread_spin_unlock (pthread_spinlock_t *lock)
00049 {
00050   *lock = 0;
00051   return 0;
00052 }
00053 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
00054 
00055 
00056 int
00057 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
00058 {
00059   /* We can ignore the `pshared' parameter.  Since we are busy-waiting
00060      all processes which can access the memory location `lock' points
00061      to can use the spinlock.  */
00062   *lock = 0;
00063   return 0;
00064 }
00065 weak_alias (__pthread_spin_init, pthread_spin_init)
00066 
00067 
00068 int
00069 __pthread_spin_destroy (pthread_spinlock_t *lock)
00070 {
00071   /* Nothing to do.  */
00072   return 0;
00073 }
00074 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)