linuxthreads/sysdeps/i386/i686/pt-machine.h

   1 /* Machine-dependent pthreads configuration and inline functions.
   2    i686 version.
   3    Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
   4    This file is part of the GNU C Library.
   5    Contributed by Richard Henderson <rth@tamu.edu>.
   6
   7    The GNU C Library is free software; you can redistribute it and/or
   8    modify it under the terms of the GNU Library General Public License as
   9    published by the Free Software Foundation; either version 2 of the
  10    License, or (at your option) any later version.
  11
  12    The GNU C Library is distributed in the hope that it will be useful,
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15    Library General Public License for more details.
  16
  17    You should have received a copy of the GNU Library General Public
  18    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  19    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  20    Boston, MA 02111-1307, USA.  */
  21
  22
  23 /* Spinlock implementation; required.  */
  24 extern inline int
  25 testandset (int *spinlock)
  26 {
  27   int ret;
  28
  29   __asm__ __volatile__ (
  30         "xchgl %0, %1"
  31         : "=r"(ret), "=m"(*spinlock)
  32         : "0"(1), "m"(*spinlock)
  33         : "memory");
  34
  35   return ret;
  36 }
  37
  38
  39 /* Get some notion of the current stack.  Need not be exactly the top
  40    of the stack, just something somewhere in the current frame.  */
  41 #define CURRENT_STACK_FRAME  stack_pointer
  42 register char * stack_pointer __asm__ ("%esp");
  43
  44
  45 /* Compare-and-swap for semaphores.  It's always available on i686.  */
  46 #define HAS_COMPARE_AND_SWAP
  47
  48 extern inline int
  49 __compare_and_swap (long int *p, long int oldval, long int newval)
  50 {
  51   char ret;
  52   long int readval;
  53
  54   __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0"
  55                         : "=q" (ret), "=m" (*p), "=a" (readval)
  56                         : "r" (newval), "m" (*p), "a" (oldval));
  57   return ret;
  58 }
  59
  60
  61 /* Use the LDT implementation only if the kernel is fixed.  */
  62 //#include "../useldt.h"