ports/sysdeps/am33/linuxthreads/pspinlock.c

   1 /* POSIX spinlock implementation.  AM33 version.
   2    Copyright 2001-2014 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.  If not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <pthread.h>
  21 #include "internals.h"
  22
  23 int
  24 __pthread_spin_lock (pthread_spinlock_t *lock)
  25 {
  26   __asm__ __volatile__("1: bset %1, (%0); beq 1b"
  27                        : : "a" (lock), "d" (1) : "memory");
  28   return 0;
  29 }
  30 weak_alias (__pthread_spin_lock, pthread_spin_lock)
  31
  32
  33 int
  34 __pthread_spin_trylock (pthread_spinlock_t *lock)
  35 {
  36   int oldval = 1;
  37
  38   __asm__ __volatile__ ("bset %0, (%1); beq 1f; clr %0; 1:" :
  39                         "+d" (oldval) : "a" (lock) : "memory");
  40
  41   return oldval ? EBUSY : 0;
  42 }
  43 weak_alias (__pthread_spin_trylock, pthread_spin_trylock)
  44
  45
  46 int
  47 __pthread_spin_unlock (pthread_spinlock_t *lock)
  48 {
  49   *lock = 0;
  50   return 0;
  51 }
  52 weak_alias (__pthread_spin_unlock, pthread_spin_unlock)
  53
  54
  55 int
  56 __pthread_spin_init (pthread_spinlock_t *lock, int pshared)
  57 {
  58   /* We can ignore the `pshared' parameter.  Since we are busy-waiting
  59      all processes which can access the memory location `lock' points
  60      to can use the spinlock.  */
  61   *lock = 0;
  62   return 0;
  63 }
  64 weak_alias (__pthread_spin_init, pthread_spin_init)
  65
  66
  67 int
  68 __pthread_spin_destroy (pthread_spinlock_t *lock)
  69 {
  70   /* Nothing to do.  */
  71   return 0;
  72 }
  73 weak_alias (__pthread_spin_destroy, pthread_spin_destroy)