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- /* Machine-dependent pthreads configuration and inline functions.
- i386 version.
- Copyright (C) 1996-2001, 2002, 2003 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 Lesser General Public License as
- published by the Free Software Foundation; either version 2.1 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
- Lesser General Public License for more details.
- You should have received a copy of the GNU Lesser 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. */
- #if defined __pentiumpro__ || defined __pentium4__ || defined __athlon__ || \
- defined __k8__
- # include "i686/pt-machine.h"
- #else
- #ifndef _PT_MACHINE_H
- #define _PT_MACHINE_H 1
- #ifndef __ASSEMBLER__
- #ifndef PT_EI
- # define PT_EI extern inline __attribute__ ((always_inline))
- #endif
- extern long int testandset (int *spinlock);
- extern int __compare_and_swap (long int *p, long int oldval, long int newval);
- /* 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);
- PT_EI int
- get_eflags (void)
- {
- int res;
- __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : );
- return res;
- }
- PT_EI void set_eflags (int newflags);
- PT_EI void
- set_eflags (int newflags)
- {
- __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc");
- }
- PT_EI int compare_and_swap_is_available (void);
- 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;
- }
- #endif /* __ASSEMBLER__ */
- #endif /* pt-machine.h */
- #endif
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