RTEMS: cpukit/include/rtems/score/smplockseq.h Source File

| RTEMS 5.4-rc2

Loading...
Searching...
No Matches
smplockseq.h
Go to the documentation of this file.
1
9/*
10 * Copyright (c) 2016 embedded brains GmbH
11 *
12 * The license and distribution terms for this file may be
13 * found in the file LICENSE in this distribution or at
14 * http://www.rtems.org/license/LICENSE.
15 */
16
17#ifndef _RTEMS_SCORE_SMPLOCKSEQ_H
18#define _RTEMS_SCORE_SMPLOCKSEQ_H
19
20#include <rtems/score/cpuopts.h>
21
22#if defined(RTEMS_SMP)
23
24#include <rtems/score/assert.h>
25#include <rtems/score/atomic.h>
26
27#ifdef __cplusplus
28extern "C" {
29#endif /* __cplusplus */
30
50typedef struct {
56 Atomic_Uint sequence;
57} SMP_sequence_lock_Control;
58
62#define SMP_SEQUENCE_LOCK_INITIALIZER { ATOMIC_INITIALIZER_UINT( 0 ) }
63
71static inline void _SMP_sequence_lock_Initialize( SMP_sequence_lock_Control *lock )
72{
73 _Atomic_Init_uint( &lock->sequence, 0 );
74}
75
83static inline void _SMP_sequence_lock_Destroy( SMP_sequence_lock_Control *lock )
84{
85 (void) lock;
86}
87
99static inline unsigned int _SMP_sequence_lock_Write_begin(
100 SMP_sequence_lock_Control *lock
101)
102{
103 unsigned int seq;
104
105 seq = _Atomic_Load_uint( &lock->sequence, ATOMIC_ORDER_RELAXED );
106 _Assert( seq % 2 == 0 );
107
108 _Atomic_Store_uint( &lock->sequence, seq + 1, ATOMIC_ORDER_RELAXED );
109
110 /* There is no atomic store with acquire/release semantics */
111 _Atomic_Fence( ATOMIC_ORDER_ACQ_REL );
112
113 return seq;
114}
115
122static inline void _SMP_sequence_lock_Write_end(
123 SMP_sequence_lock_Control *lock,
124 unsigned int seq
125)
126{
127 _Atomic_Store_uint( &lock->sequence, seq + 2, ATOMIC_ORDER_RELEASE );
128}
129
139static inline unsigned int _SMP_sequence_lock_Read_begin(
140 const SMP_sequence_lock_Control *lock
141)
142{
143 return _Atomic_Load_uint( &lock->sequence, ATOMIC_ORDER_ACQUIRE );
144}
145
157static inline bool _SMP_sequence_lock_Read_retry(
158 SMP_sequence_lock_Control *lock,
159 unsigned int seq
160)
161{
162 unsigned int seq2;
163
164 seq2 = _Atomic_Fetch_add_uint( &lock->sequence, 0, ATOMIC_ORDER_RELEASE );
165 return seq != seq2 || seq % 2 != 0;
166}
167
170#ifdef __cplusplus
171}
172#endif /* __cplusplus */
173
174#endif /* RTEMS_SMP */
175
176#endif /* _RTEMS_SCORE_SMPLOCKSEQ_H */
assert.h
Information for the Assert Handler.
_Assert
#define _Assert(_e)
Assertion similar to assert() controlled via RTEMS_DEBUG instead of NDEBUG.
Definition: assert.h:100
atomic.h
Atomic Operations API.