Subversion Repositories openrisc_2011-10-31

/* Machine-dependent pthreads configuration and inline functions.

   i386 version.

   Copyright (C) 1996,1997,1998,1999,2000,2001 Free Software Foundation, Inc.

   This file is part of the GNU C Library.

   Contributed by Richard Henderson <rth@tamu.edu>.

   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; see the file COPYING.LIB.  If not,

   write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,

   Boston, MA 02111-1307, USA.  */

#ifndef PT_EI

# define PT_EI extern inline

#endif

/* Get some notion of the current stack.  Need not be exactly the top

   of the stack, just something somewhere in the current frame.  */

#define CURRENT_STACK_FRAME  __builtin_frame_address (0)

/* Spinlock implementation; required.  */

PT_EI long int

testandset (int *spinlock)

{

  long int ret;

  __asm__ __volatile__(

       "xchgl %0, %1"

       : "=r"(ret), "=m"(*spinlock)

       : "0"(1), "m"(*spinlock)

       : "memory");

  return ret;

}

/* Compare-and-swap for semaphores.

   Available on the 486 and above, but not on the 386.

   We test dynamically whether it's available or not. */

#define HAS_COMPARE_AND_SWAP

#define TEST_FOR_COMPARE_AND_SWAP

PT_EI int

__compare_and_swap (long int *p, long int oldval, long int newval)

{

  char ret;

  long int readval;

  __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0"

                        : "=q" (ret), "=m" (*p), "=a" (readval)

                        : "r" (newval), "m" (*p), "a" (oldval)

                        : "memory");

  return ret;

}

PT_EI int

get_eflags (void)

{

  int res;

  __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : );

  return res;

}

PT_EI void

set_eflags (int newflags)

{

  __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc");

}

PT_EI int

compare_and_swap_is_available (void)

{

  int oldflags = get_eflags ();

  int changed;

  /* Flip AC bit in EFLAGS.  */

  set_eflags (oldflags ^ 0x40000);

  /* See if bit changed.  */

  changed = (get_eflags () ^ oldflags) & 0x40000;

  /* Restore EFLAGS.  */

  set_eflags (oldflags);

  /* If the AC flag did not change, it's a 386 and it lacks cmpxchg.

     Otherwise, it's a 486 or above and it has cmpxchg.  */

  return changed != 0;

}