sysdeps/x86_64/nptl/pthread_spin_trylock.S

   1 /* Copyright (C) 2002-2018 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
   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 <pthread-errnos.h>
  20 #include <sysdep.h>
  21
  22
  23 #ifdef UP
  24 # define LOCK
  25 #else
  26 # define LOCK lock
  27 #endif
  28
  29 ENTRY(pthread_spin_trylock)
  30         movl    $1, %eax
  31         xorl    %ecx, %ecx
  32         LOCK
  33         cmpxchgl %ecx, (%rdi)
  34         movl    $EBUSY, %eax
  35         cmovel  %ecx, %eax
  36         retq
  37 END(pthread_spin_trylock)