sysdeps/hppa/linuxthreads/pspinlock.c

   1 /* POSIX spinlock implementation.  hppa version.
   2    Copyright (C) 2000 Free Software Foundation, Inc.
   3    This file is part of the GNU C Library.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Lesser General Public License as
   7    published by the Free Software Foundation; either version 2.1 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <pthread.h>
  22 #include "internals.h"
  23
  24 int
  25 __pthread_spin_lock (pthread_spinlock_t *lock)
  26 {
  27   volatile unsigned int *addr = __ldcw_align (lock);
  28
  29   while (__ldcw (addr) == 0)
  30     while (*addr == 0) ;
  31
  32   return 0;
  33 }
  34 weak_alias (__pthread_spin_lock, pthread_spin_lock)
  35
  36
  37 int
  38 __pthread_spin_trylock (pthread_spinlock_t *lock)
  39 {
  40   volatile unsigned int *a = __ldcw_align (lock);
  41
  42   return __ldcw (a) ? 0 : EBUSY;
  43 }
  44 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
  45
  46
  47 int
  48 __pthread_spin_unlock (pthread_spinlock_t *lock)
  49 {
  50   volatile unsigned int *a = __ldcw_align (lock);
  51   int tmp = 1;
  52   /* This should be a memory barrier to newer compilers */
  53   __asm__ __volatile__ ("stw,ma %1,0(%0)"
  54                         : : "r" (a), "r" (tmp) : "memory");
  55   return 0;
  56 }
  57 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
  58
  59
  60 int
  61 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
  62 {
  63   /* We can ignore the `pshared' parameter.  Since we are busy-waiting
  64      all processes which can access the memory location `lock' points
  65      to can use the spinlock.  */
  66   volatile unsigned int *a = __ldcw_align (lock);
  67   int tmp = 1;
  68   /* This should be a memory barrier to newer compilers */
  69   __asm__ __volatile__ ("stw,ma %1,0(%0)"
  70                         : : "r" (a), "r" (tmp) : "memory");
  71   return 0;
  72 }
  73 weak_alias (__pthread_spin_init, pthread_spin_init)
  74
  75
  76 int
  77 __pthread_spin_destroy (pthread_spinlock_t *lock)
  78 {
  79   /* Nothing to do.  */
  80   return 0;
  81 }
  82 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)