google3/third_party/grte/v4_src/glibc-2.19/ports/sysdeps/am33/linuxthreads/pspinlock.c

/* POSIX spinlock implementation.  AM33 version.
   Copyright 2001-2014 Free Software Foundation, Inc.
   This file is part of the GNU C Library.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Library General Public License as
   published by the Free Software Foundation; either version 2 of the
   License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Library General Public License for more details.

   You should have received a copy of the GNU Library General Public
   License along with the GNU C Library.  If not, see
   <http://www.gnu.org/licenses/>.  */

#include <errno.h>
#include <pthread.h>
#include "internals.h"

int
__pthread_spin_lock (pthread_spinlock_t *lock)
{
  __asm__ __volatile__("1: bset %1, (%0); beq 1b"
		       : : "a" (lock), "d" (1) : "memory");
  return 0;
}
weak_alias (__pthread_spin_lock, pthread_spin_lock)


int
__pthread_spin_trylock (pthread_spinlock_t *lock)
{
  int oldval = 1;

  __asm__ __volatile__ ("bset %0, (%1); beq 1f; clr %0; 1:" :
			"+d" (oldval) : "a" (lock) : "memory");

  return oldval ? EBUSY : 0;
}
weak_alias (__pthread_spin_trylock, pthread_spin_trylock)


int
__pthread_spin_unlock (pthread_spinlock_t *lock)
{
  *lock = 0;
  return 0;
}
weak_alias (__pthread_spin_unlock, pthread_spin_unlock)


int
__pthread_spin_init (pthread_spinlock_t *lock, int pshared)
{
  /* We can ignore the `pshared' parameter.  Since we are busy-waiting
     all processes which can access the memory location `lock' points
     to can use the spinlock.  */
  *lock = 0;
  return 0;
}
weak_alias (__pthread_spin_init, pthread_spin_init)


int
__pthread_spin_destroy (pthread_spinlock_t *lock)
{
  /* Nothing to do.  */
  return 0;
}
weak_alias (__pthread_spin_destroy, pthread_spin_destroy)