1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
|
/*
* %CopyrightBegin%
*
* Copyright Ericsson AB 2005-2011. All Rights Reserved.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* %CopyrightEnd%
*/
/*
* Native ethread rwlocks on x86/x86-64.
* Author: Mikael Pettersson.
*
* This code requires a 486 or newer processor.
*/
#ifndef ETHREAD_I386_RWLOCK_H
#define ETHREAD_I386_RWLOCK_H
#define ETHR_HAVE_NATIVE_RWSPINLOCKS 1
#define ETHR_NATIVE_RWSPINLOCK_IMPL "ethread"
/* XXX: describe the algorithm */
typedef struct {
volatile int lock;
} ethr_native_rwlock_t;
#if defined(ETHR_TRY_INLINE_FUNCS) || defined(ETHR_AUX_IMPL__)
#define ETHR_RWLOCK_OFFSET (1<<24)
static ETHR_INLINE void
ethr_native_rwlock_init(ethr_native_rwlock_t *lock)
{
lock->lock = 0;
}
static ETHR_INLINE void
ethr_native_read_unlock(ethr_native_rwlock_t *lock)
{
__asm__ __volatile__(
"lock; decl %0"
: "=m"(lock->lock)
: "m"(lock->lock));
}
static ETHR_INLINE int
ethr_native_read_trylock(ethr_native_rwlock_t *lock)
{
int tmp;
tmp = 1;
__asm__ __volatile__(
"lock; xaddl %0, %1"
: "=r"(tmp)
: "m"(lock->lock), "0"(tmp));
/* tmp is now the lock's previous value */
if (__builtin_expect(tmp >= 0, 1))
return 1;
ethr_native_read_unlock(lock);
return 0;
}
static ETHR_INLINE int
ethr_native_read_is_locked(ethr_native_rwlock_t *lock)
{
return lock->lock < 0;
}
static ETHR_INLINE void
ethr_native_read_lock(ethr_native_rwlock_t *lock)
{
for(;;) {
if (__builtin_expect(ethr_native_read_trylock(lock) != 0, 1))
break;
do {
__asm__ __volatile__("rep;nop" : "=m"(lock->lock) : : "memory");
} while (ethr_native_read_is_locked(lock));
}
}
static ETHR_INLINE void
ethr_native_write_unlock(ethr_native_rwlock_t *lock)
{
__asm__ __volatile__(
"lock; addl %2,%0"
: "=m"(lock->lock)
: "m"(lock->lock), "i"(ETHR_RWLOCK_OFFSET));
}
static ETHR_INLINE int
ethr_native_write_trylock(ethr_native_rwlock_t *lock)
{
int tmp;
tmp = -ETHR_RWLOCK_OFFSET;
__asm__ __volatile__(
"lock; xaddl %0, %1"
: "=r"(tmp)
: "m"(lock->lock), "0"(tmp));
/* tmp is now the lock's previous value */
if (__builtin_expect(tmp == 0, 1))
return 1;
ethr_native_write_unlock(lock);
return 0;
}
static ETHR_INLINE int
ethr_native_write_is_locked(ethr_native_rwlock_t *lock)
{
return lock->lock != 0;
}
static ETHR_INLINE void
ethr_native_write_lock(ethr_native_rwlock_t *lock)
{
for(;;) {
if (__builtin_expect(ethr_native_write_trylock(lock) != 0, 1))
break;
do {
__asm__ __volatile__("rep;nop" : "=m"(lock->lock) : : "memory");
} while (ethr_native_write_is_locked(lock));
}
}
#endif /* ETHR_TRY_INLINE_FUNCS */
#endif /* ETHREAD_I386_RWLOCK_H */
|
