sysdeps/am33/linuxthreads/pspinlock.c

   1 /* POSIX spinlock implementation.  AM33 version.
   2    Copyright 2001 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 Library General Public License as
   7    published by the Free Software Foundation; either version 2 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    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library 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   __asm__ __volatile__("1: bset %1, (%0); beq 1b"
  28                        : : "a" (lock), "d" (1) : "memory");
  29   return 0;
  30 }
  31 weak_alias (__pthread_spin_lock, pthread_spin_lock)
  32
  33
  34 int
  35 __pthread_spin_trylock (pthread_spinlock_t *lock)
  36 {
  37   int oldval = 1;
  38
  39   __asm__ __volatile__ ("bset %0, (%1); beq 1f; clr %0; 1:" :
  40                         "+d" (oldval) : "a" (lock) : "memory");
  41
  42   return oldval ? EBUSY : 0;
  43 }
  44 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
  45
  46
  47 int
  48 __pthread_spin_unlock (pthread_spinlock_t *lock)
  49 {
  50   *lock = 0;
  51   return 0;
  52 }
  53 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
  54
  55
  56 int
  57 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
  58 {
  59   /* We can ignore the `pshared' parameter.  Since we are busy-waiting
  60      all processes which can access the memory location `lock' points
  61      to can use the spinlock.  */
  62   *lock = 0;
  63   return 0;
  64 }
  65 weak_alias (__pthread_spin_init, pthread_spin_init)
  66
  67
  68 int
  69 __pthread_spin_destroy (pthread_spinlock_t *lock)
  70 {
  71   /* Nothing to do.  */
  72   return 0;
  73 }
  74 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)