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5afdca00 UD |
1 | /* Machine-dependent pthreads configuration and inline functions. |
2 | i386 version. | |
d347a4ab | 3 | Copyright (C) 1996-2001, 2002, 2003 Free Software Foundation, Inc. |
5afdca00 UD |
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 | |
cc7375ce RM |
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 | |
5afdca00 UD |
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 | |
cc7375ce | 15 | Lesser General Public License for more details. |
5afdca00 | 16 | |
cc7375ce | 17 | You should have received a copy of the GNU Lesser General Public |
5afdca00 UD |
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 | ||
b6a0a996 UD |
22 | #ifndef _PT_MACHINE_H |
23 | #define _PT_MACHINE_H 1 | |
24 | ||
78ce5a3b | 25 | #ifndef __ASSEMBLER__ |
9a29bc37 | 26 | #ifndef PT_EI |
d347a4ab | 27 | # define PT_EI extern inline __attribute__ ((always_inline)) |
9a29bc37 | 28 | #endif |
5afdca00 | 29 | |
f68137c9 AJ |
30 | extern long int testandset (int *spinlock); |
31 | extern int __compare_and_swap (long int *p, long int oldval, long int newval); | |
32 | ||
d7a4856e UD |
33 | /* Get some notion of the current stack. Need not be exactly the top |
34 | of the stack, just something somewhere in the current frame. */ | |
4e5b051f | 35 | #define CURRENT_STACK_FRAME __builtin_frame_address (0) |
d7a4856e UD |
36 | |
37 | ||
5afdca00 | 38 | /* Spinlock implementation; required. */ |
79f757a4 | 39 | PT_EI long int |
5afdca00 UD |
40 | testandset (int *spinlock) |
41 | { | |
79f757a4 | 42 | long int ret; |
5afdca00 | 43 | |
7afab53d UD |
44 | __asm__ __volatile__( |
45 | "xchgl %0, %1" | |
46 | : "=r"(ret), "=m"(*spinlock) | |
47 | : "0"(1), "m"(*spinlock) | |
48 | : "memory"); | |
5afdca00 UD |
49 | |
50 | return ret; | |
51 | } | |
52 | ||
53 | ||
5afdca00 UD |
54 | /* Compare-and-swap for semaphores. |
55 | Available on the 486 and above, but not on the 386. | |
56 | We test dynamically whether it's available or not. */ | |
57 | ||
58 | #define HAS_COMPARE_AND_SWAP | |
0ca7e46e | 59 | #define TEST_FOR_COMPARE_AND_SWAP |
5afdca00 | 60 | |
9a29bc37 | 61 | PT_EI int |
5afdca00 UD |
62 | __compare_and_swap (long int *p, long int oldval, long int newval) |
63 | { | |
64 | char ret; | |
65 | long int readval; | |
66 | ||
67 | __asm__ __volatile__ ("lock; cmpxchgl %3, %1; sete %0" | |
68 | : "=q" (ret), "=m" (*p), "=a" (readval) | |
d17a729b UD |
69 | : "r" (newval), "m" (*p), "a" (oldval) |
70 | : "memory"); | |
5afdca00 UD |
71 | return ret; |
72 | } | |
73 | ||
74 | ||
7ccc548b | 75 | PT_EI int |
5afdca00 UD |
76 | get_eflags (void) |
77 | { | |
78 | int res; | |
79 | __asm__ __volatile__ ("pushfl; popl %0" : "=r" (res) : ); | |
80 | return res; | |
81 | } | |
82 | ||
83 | ||
7ccc548b | 84 | PT_EI void |
5afdca00 UD |
85 | set_eflags (int newflags) |
86 | { | |
87 | __asm__ __volatile__ ("pushl %0; popfl" : : "r" (newflags) : "cc"); | |
88 | } | |
89 | ||
90 | ||
9a29bc37 | 91 | PT_EI int |
5afdca00 UD |
92 | compare_and_swap_is_available (void) |
93 | { | |
94 | int oldflags = get_eflags (); | |
95 | int changed; | |
96 | /* Flip AC bit in EFLAGS. */ | |
97 | set_eflags (oldflags ^ 0x40000); | |
98 | /* See if bit changed. */ | |
99 | changed = (get_eflags () ^ oldflags) & 0x40000; | |
100 | /* Restore EFLAGS. */ | |
101 | set_eflags (oldflags); | |
102 | /* If the AC flag did not change, it's a 386 and it lacks cmpxchg. | |
103 | Otherwise, it's a 486 or above and it has cmpxchg. */ | |
104 | return changed != 0; | |
105 | } | |
78ce5a3b | 106 | #endif /* __ASSEMBLER__ */ |
b6a0a996 UD |
107 | |
108 | #endif /* pt-machine.h */ |