1 /* Machine-dependent pthreads configuration and inline functions.
2 i686 version.
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>.
6
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.
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 Lesser General Public License for more details.
16
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 not,
19 write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
20 Boston, MA 02111-1307, USA. */
21
22 #ifndef _PT_MACHINE_H
23 #define _PT_MACHINE_H 1
24
25 #ifndef PT_EI
26 # define PT_EI __extern_always_inline
27 #endif
28 //l4/#include <bits/kernel-features.h>
29
30 #ifndef __ASSEMBLER__
31 extern long int testandset (int *spinlock);
32 extern int __compare_and_swap (long int *p, long int oldval, long int newval);
33
34 /* Get some notion of the current stack. Need not be exactly the top
35 of the stack, just something somewhere in the current frame. */
36 #define CURRENT_STACK_FRAME __builtin_frame_address (0)
37
38
39 /* Spinlock implementation; required. */
40 PT_EI long int
testandset(int * spinlock)41 testandset (int *spinlock)
42 {
43 long int ret;
44
45 __asm__ __volatile__ (
46 "xchgl %0, %1"
47 : "=r" (ret), "=m" (*spinlock)
48 : "0" (1), "m" (*spinlock)
49 : "memory");
50
51 return ret;
52 }
53
54
55 /* Compare-and-swap for semaphores. It's always available on i686. */
56 #define HAS_COMPARE_AND_SWAP
57
58 PT_EI int
__compare_and_swap(long int * p,long int oldval,long int newval)59 __compare_and_swap (long int *p, long int oldval, long int newval)
60 {
61 char ret;
62 long int readval;
63
64 __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0"
65 : "=q" (ret), "=m" (*p), "=a" (readval)
66 : "r" (newval), "m" (*p), "a" (oldval)
67 : "memory");
68 return ret;
69 }
70 #endif
71
72 #if __ASSUME_LDT_WORKS > 0
73 #include "../useldt.h"
74 #endif
75
76 /* The P4 and above really want some help to prevent overheating. */
77 #define BUSY_WAIT_NOP __asm__ ("rep; nop")
78
79 #endif /* pt-machine.h */
80