nptl/sysdeps/powerpc/pthread_spin_trylock.c

   1 /* Copyright (C) 2003-2014 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Paul Mackerras <paulus@au.ibm.com>, 2003.
   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
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include "pthreadP.h"
  21
  22 int
  23 pthread_spin_trylock (lock)
  24      pthread_spinlock_t *lock;
  25 {
  26   unsigned int old;
  27   int err = EBUSY;
  28
  29   asm ("1:      lwarx   %0,0,%2\n"
  30        "        cmpwi   0,%0,0\n"
  31        "        bne     2f\n"
  32        "        stwcx.  %3,0,%2\n"
  33        "        bne-    1b\n"
  34        "        li      %1,0\n"
  35        "        isync\n"
  36        "2:      "
  37        : "=&r" (old), "=&r" (err)
  38        : "r" (lock), "r" (1), "1" (err)
  39        : "cr0", "memory");
  40
  41   return err;
  42 }