chbsem.h
9.88 KB
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
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
/*
ChibiOS/RT - Copyright (C) 2006,2007,2008,2009,2010,
2011,2012 Giovanni Di Sirio.
This file is part of ChibiOS/RT.
ChibiOS/RT is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
ChibiOS/RT is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
---
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes ChibiOS/RT, without being obliged to provide
the source code for any proprietary components. See the file exception.txt
for full details of how and when the exception can be applied.
*/
/**
* @file chbsem.h
* @brief Binary semaphores structures and macros.
*
* @addtogroup binary_semaphores
* @details Binary semaphores related APIs and services.
*
* <h2>Operation mode</h2>
* Binary semaphores are implemented as a set of macros that use the
* existing counting semaphores primitives. The difference between
* counting and binary semaphores is that the counter of binary
* semaphores is not allowed to grow above the value 1. Repeated
* signal operation are ignored. A binary semaphore can thus have
* only two defined states:
* - <b>Taken</b>, when its counter has a value of zero or lower
* than zero. A negative number represent the number of threads
* queued on the binary semaphore.
* - <b>Not taken</b>, when its counter has a value of one.
* .
* Binary semaphores are different from mutexes because there is no
* the concept of ownership, a binary semaphore can be taken by a
* thread and signaled by another thread or an interrupt handler,
* mutexes can only be taken and released by the same thread. Another
* difference is that binary semaphores, unlike mutexes, do not
* implement the priority inheritance protocol.<br>
* In order to use the binary semaphores APIs the @p CH_USE_SEMAPHORES
* option must be enabled in @p chconf.h.
* @{
*/
#ifndef _CHBSEM_H_
#define _CHBSEM_H_
#if CH_USE_SEMAPHORES || defined(__DOXYGEN__)
/**
* @extends Semaphore
*
* @brief Binary semaphore type.
*/
typedef struct {
Semaphore bs_sem;
} BinarySemaphore;
/**
* @brief Data part of a static semaphore initializer.
* @details This macro should be used when statically initializing a semaphore
* that is part of a bigger structure.
*
* @param[in] name the name of the semaphore variable
* @param[in] taken the semaphore initial state
*/
#define _BSEMAPHORE_DATA(name, taken) \
{_SEMAPHORE_DATA(name.bs_sem, ((taken) ? 0 : 1))}
/**
* @brief Static semaphore initializer.
* @details Statically initialized semaphores require no explicit
* initialization using @p chSemInit().
*
* @param[in] name the name of the semaphore variable
* @param[in] taken the semaphore initial state
*/
#define BSEMAPHORE_DECL(name, taken) \
BinarySemaphore name = _BSEMAPHORE_DATA(name, taken)
/**
* @name Macro Functions
* @{
*/
/**
* @brief Initializes a binary semaphore.
*
* @param[out] bsp pointer to a @p BinarySemaphore structure
* @param[in] taken initial state of the binary semaphore:
* - @a FALSE, the initial state is not taken.
* - @a TRUE, the initial state is taken.
* .
*
* @init
*/
#define chBSemInit(bsp, taken) chSemInit(&(bsp)->bs_sem, (taken) ? 0 : 1)
/**
* @brief Wait operation on the binary semaphore.
*
* @param[in] bsp pointer to a @p BinarySemaphore structure
* @return A message specifying how the invoking thread has been
* released from the semaphore.
* @retval RDY_OK if the binary semaphore has been successfully taken.
* @retval RDY_RESET if the binary semaphore has been reset using
* @p bsemReset().
*
* @api
*/
#define chBSemWait(bsp) chSemWait(&(bsp)->bs_sem)
/**
* @brief Wait operation on the binary semaphore.
*
* @param[in] bsp pointer to a @p BinarySemaphore structure
* @return A message specifying how the invoking thread has been
* released from the semaphore.
* @retval RDY_OK if the binary semaphore has been successfully taken.
* @retval RDY_RESET if the binary semaphore has been reset using
* @p bsemReset().
*
* @sclass
*/
#define chBSemWaitS(bsp) chSemWaitS(&(bsp)->bs_sem)
/**
* @brief Wait operation on the binary semaphore.
*
* @param[in] bsp pointer to a @p BinarySemaphore structure
* @param[in] time the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return A message specifying how the invoking thread has been
* released from the semaphore.
* @retval RDY_OK if the binary semaphore has been successfully taken.
* @retval RDY_RESET if the binary semaphore has been reset using
* @p bsemReset().
* @retval RDY_TIMEOUT if the binary semaphore has not been signaled or reset
* within the specified timeout.
*
* @api
*/
#define chBSemWaitTimeout(bsp, time) chSemWaitTimeout(&(bsp)->bs_sem, (time))
/**
* @brief Wait operation on the binary semaphore.
*
* @param[in] bsp pointer to a @p BinarySemaphore structure
* @param[in] time the number of ticks before the operation timeouts,
* the following special values are allowed:
* - @a TIME_IMMEDIATE immediate timeout.
* - @a TIME_INFINITE no timeout.
* .
* @return A message specifying how the invoking thread has been
* released from the semaphore.
* @retval RDY_OK if the binary semaphore has been successfully taken.
* @retval RDY_RESET if the binary semaphore has been reset using
* @p bsemReset().
* @retval RDY_TIMEOUT if the binary semaphore has not been signaled or reset
* within the specified timeout.
*
* @sclass
*/
#define chBSemWaitTimeoutS(bsp, time) chSemWaitTimeoutS(&(bsp)->bs_sem, (time))
/**
* @brief Reset operation on the binary semaphore.
* @note The released threads can recognize they were waked up by a reset
* rather than a signal because the @p bsemWait() will return
* @p RDY_RESET instead of @p RDY_OK.
*
* @param[in] bsp pointer to a @p BinarySemaphore structure
* @param[in] taken new state of the binary semaphore
* - @a FALSE, the new state is not taken.
* - @a TRUE, the new state is taken.
* .
*
* @api
*/
#define chBSemReset(bsp, taken) chSemReset(&(bsp)->bs_sem, (taken) ? 0 : 1)
/**
* @brief Reset operation on the binary semaphore.
* @note The released threads can recognize they were waked up by a reset
* rather than a signal because the @p bsemWait() will return
* @p RDY_RESET instead of @p RDY_OK.
* @note This function does not reschedule.
*
* @param[in] bsp pointer to a @p BinarySemaphore structure
* @param[in] taken new state of the binary semaphore
* - @a FALSE, the new state is not taken.
* - @a TRUE, the new state is taken.
* .
*
* @iclass
*/
#define chBSemResetI(bsp, taken) chSemResetI(&(bsp)->bs_sem, (taken) ? 0 : 1)
/**
* @brief Performs a signal operation on a binary semaphore.
*
* @param[in] bsp pointer to a @p BinarySemaphore structure
*
* @api
*/
#define chBSemSignal(bsp) { \
chSysLock(); \
chBSemSignalI((bsp)); \
chSchRescheduleS(); \
chSysUnlock(); \
}
/**
* @brief Performs a signal operation on a binary semaphore.
* @note This function does not reschedule.
*
* @param[in] bsp pointer to a @p BinarySemaphore structure
*
* @iclass
*/
#define chBSemSignalI(bsp) { \
if ((bsp)->bs_sem.s_cnt < 1) \
chSemSignalI(&(bsp)->bs_sem); \
}
/**
* @brief Returns the binary semaphore current state.
*
* @param[in] bsp pointer to a @p BinarySemaphore structure
* @return The binary semaphore current state.
* @retval FALSE if the binary semaphore is not taken.
* @retval TRUE if the binary semaphore is taken.
*
* @iclass
*/
#define chBSemGetStateI(bsp) ((bsp)->bs_sem.s_cnt > 0 ? FALSE : TRUE)
/** @} */
#endif /* CH_USE_SEMAPHORES */
#endif /* _CHBSEM_H_ */
/** @} */