1 /* Machine-dependent pthreads configuration and inline functions.
3 Copyright (C) 1996-2001, 2002, 2003 Free Software Foundation, Inc.
4 This file is part of the GNU C Library.
5 Contributed by Richard Henderson <rth@tamu.edu>.
7 The GNU C Library is free software; you can redistribute it and/or
8 modify it under the terms of the GNU Lesser General Public License as
9 published by the Free Software Foundation; either version 2.1 of the
10 License, or (at your option) any later version.
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 Lesser General Public License for more details.
17 You should have received a copy of the GNU Lesser General Public
18 License along with the GNU C Library; see the file COPYING.LIB. If
19 not, see <http://www.gnu.org/licenses/>. */
21 #if defined __pentiumpro__ || defined __pentium4__ || defined __athlon__ || \
23 # include "i686/pt-machine.h"
27 #define _PT_MACHINE_H 1
31 # define PT_EI __extern_always_inline
34 extern long int testandset (int *spinlock);
35 extern int __compare_and_swap (long int *p, long int oldval, long int newval);
37 /* Get some notion of the current stack. Need not be exactly the top
38 of the stack, just something somewhere in the current frame. */
39 #define CURRENT_STACK_FRAME __builtin_frame_address (0)
42 /* Spinlock implementation; required. */
44 testandset (int *spinlock)
50 : "=r"(ret), "=m"(*spinlock)
51 : "0"(1), "m"(*spinlock)
58 /* Compare-and-swap for semaphores.
59 Available on the 486 and above, but not on the 386.
60 We test dynamically whether it's available or not. */
62 #define HAS_COMPARE_AND_SWAP
63 #define TEST_FOR_COMPARE_AND_SWAP
66 __compare_and_swap (long int *p, long int oldval, long int newval)
71 __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0"
72 : "=q" (ret), "=m" (*p), "=a" (readval)
73 : "r" (newval), "m" (*p), "a" (oldval)
79 PT_EI int get_eflags (void);
84 __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : );
89 PT_EI void set_eflags (int newflags);
91 set_eflags (int newflags)
93 __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc");
97 PT_EI int compare_and_swap_is_available (void);
99 compare_and_swap_is_available (void)
101 int oldflags = get_eflags ();
103 /* Flip AC bit in EFLAGS. */
104 set_eflags (oldflags ^ 0x40000);
105 /* See if bit changed. */
106 changed = (get_eflags () ^ oldflags) & 0x40000;
107 /* Restore EFLAGS. */
108 set_eflags (oldflags);
109 /* If the AC flag did not change, it's a 386 and it lacks cmpxchg.
110 Otherwise, it's a 486 or above and it has cmpxchg. */
113 #endif /* __ASSEMBLER__ */
115 #endif /* pt-machine.h */