nptl/sysdeps/unix/sysv/linux/x86_64/sem_trywait.S

   1 /* Copyright (C) 2002, 2003, 2005, 2007, 2011 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 <sysdep.h>
  20 #include <lowlevellock.h>
  21 #include <shlib-compat.h>
  22 #include <pthread-errnos.h>
  23
  24         .text
  25
  26         .globl  sem_trywait
  27         .type   sem_trywait,@function
  28         .align  16
  29 sem_trywait:
  30         movl    (%rdi), %eax
  31 2:      testl   %eax, %eax
  32         jz      1f
  33
  34         leal    -1(%rax), %edx
  35         LOCK
  36         cmpxchgl %edx, (%rdi)
  37         jne     2b
  38
  39         xorl    %eax, %eax
  40         retq
  41
  42 1:
  43         movq    errno@gottpoff(%rip), %rdx
  44         movl    $EAGAIN, %fs:(%rdx)
  45         orl     $-1, %eax
  46         retq
  47         .size   sem_trywait,.-sem_trywait