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Semaphore.h
1 /* mbed Microcontroller Library
2  * Copyright (c) 2006-2012 ARM Limited
3  *
4  * Permission is hereby granted, free of charge, to any person obtaining a copy
5  * of this software and associated documentation files (the "Software"), to deal
6  * in the Software without restriction, including without limitation the rights
7  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
8  * copies of the Software, and to permit persons to whom the Software is
9  * furnished to do so, subject to the following conditions:
10  *
11  * The above copyright notice and this permission notice shall be included in
12  * all copies or substantial portions of the Software.
13  *
14  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17  * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
20  * SOFTWARE.
21  */
22 #ifndef SEMAPHORE_H
23 #define SEMAPHORE_H
24 
25 #include <stdint.h>
26 #include "cmsis_os2.h"
27 #include "mbed_rtos1_types.h"
28 #include "mbed_rtos_storage.h"
29 #include "platform/mbed_toolchain.h"
30 #include "platform/NonCopyable.h"
31 
32 namespace rtos {
33 /** \addtogroup rtos */
34 /** @{*/
35 /**
36  * \defgroup rtos_Semaphore Semaphore class
37  * @{
38  */
39 
40 /** The Semaphore class is used to manage and protect access to a set of shared resources.
41  *
42  * @note
43  * Memory considerations: The semaphore control structures will be created on current thread's stack, both for the mbed OS
44  * and underlying RTOS objects (static or dynamic RTOS memory pools are not being used).
45  */
46 class Semaphore : private mbed::NonCopyable<Semaphore> {
47 public:
48  /** Create and Initialize a Semaphore object used for managing resources.
49  @param count number of available resources; maximum index value is (count-1). (default: 0).
50 
51  @note You cannot call this function from ISR context.
52  */
53  Semaphore(int32_t count = 0);
54 
55  /** Create and Initialize a Semaphore object used for managing resources.
56  @param count number of available resources
57  @param max_count maximum number of available resources
58 
59  @note You cannot call this function from ISR context.
60  */
61  Semaphore(int32_t count, uint16_t max_count);
62 
63  /** Wait until a Semaphore resource becomes available.
64 
65  @deprecated Do not use this function. This function has been replaced with acquire(), try_acquire() and try_acquire_for() functions.
66 
67  @param millisec timeout value. (default: osWaitForever).
68  @return number of available tokens, before taking one; or -1 in case of incorrect parameters
69 
70  @note You may call this function from ISR context if the millisec parameter is set to 0.
71  */
72  MBED_DEPRECATED_SINCE("mbed-os-5.13", "Replaced with acquire, try_acquire() and try_acquire_for() functions")
73  int32_t wait(uint32_t millisec = osWaitForever);
74 
75  /** Wait until a Semaphore resource becomes available.
76 
77  @deprecated Do not use this function. This function has been replaced with try_acquire_until().
78 
79  @param millisec absolute timeout time, referenced to Kernel::get_ms_count()
80  @return number of available tokens, before taking one; or -1 in case of incorrect parameters
81  @note the underlying RTOS may have a limit to the maximum wait time
82  due to internal 32-bit computations, but this is guaranteed to work if the
83  wait is <= 0x7fffffff milliseconds (~24 days). If the limit is exceeded,
84  the acquire attempt will time out earlier than specified.
85 
86  @note You cannot call this function from ISR context.
87  */
88  MBED_DEPRECATED_SINCE("mbed-os-5.13", "Replaced with try_acquire_until()")
89  int32_t wait_until(uint64_t millisec);
90 
91  /** Wait until a Semaphore resource becomes available.
92 
93  @note You cannot call this function from ISR context.
94  */
95  void acquire();
96 
97  /** Try to acquire a Semaphore resource, and return immediately
98  @return true if a resource was acquired, false otherwise.
99  @note equivalent to try_acquire_for(0)
100 
101  @note You may call this function from ISR context.
102  */
103  bool try_acquire();
104 
105  /** Wait until a Semaphore resource becomes available.
106  @param millisec timeout value.
107  @return true if a resource was acquired, false otherwise.
108 
109  @note You may call this function from ISR context if the millisec parameter is set to 0.
110  */
111  bool try_acquire_for(uint32_t millisec);
112 
113  /** Wait until a Semaphore resource becomes available.
114  @param millisec absolute timeout time, referenced to Kernel::get_ms_count()
115  @return true if a resource was acquired, false otherwise.
116  @note the underlying RTOS may have a limit to the maximum wait time
117  due to internal 32-bit computations, but this is guaranteed to work if the
118  wait is <= 0x7fffffff milliseconds (~24 days). If the limit is exceeded,
119  the acquire attempt will time out earlier than specified.
120 
121  @note You cannot call this function from ISR context.
122  */
123  bool try_acquire_until(uint64_t millisec);
124 
125  /** Release a Semaphore resource that was obtain with Semaphore::acquire.
126  @return status code that indicates the execution status of the function:
127  @a osOK the token has been correctly released.
128  @a osErrorResource the maximum token count has been reached.
129  @a osErrorParameter internal error.
130 
131  @note You may call this function from ISR context.
132  */
133  osStatus release(void);
134 
135  /** Semaphore destructor
136  *
137  * @note You cannot call this function from ISR context.
138  */
139  ~Semaphore();
140 
141 private:
142  void constructor(int32_t count, uint16_t max_count);
143 
144  int32_t _wait(uint32_t millisec);
145 
146  osSemaphoreId_t _id;
147  mbed_rtos_storage_semaphore_t _obj_mem;
148 };
149 /** @}*/
150 /** @}*/
151 }
152 #endif
153 
154 
rtos::Semaphore::wait_until
int32_t wait_until(uint64_t millisec)
Wait until a Semaphore resource becomes available.
rtos::Semaphore::try_acquire_until
bool try_acquire_until(uint64_t millisec)
Wait until a Semaphore resource becomes available.
rtos::Semaphore::try_acquire_for
bool try_acquire_for(uint32_t millisec)
Wait until a Semaphore resource becomes available.
rtos::Semaphore::release
osStatus release(void)
Release a Semaphore resource that was obtain with Semaphore::acquire.
rtos::Semaphore
The Semaphore class is used to manage and protect access to a set of shared resources.
Definition: Semaphore.h:46
rtos::Semaphore::try_acquire
bool try_acquire()
Try to acquire a Semaphore resource, and return immediately.
mbed::NonCopyable
Prevents generation of copy constructor and copy assignment operator in derived classes.
Definition: NonCopyable.h:168
rtos::Semaphore::wait
int32_t wait(uint32_t millisec=osWaitForever)
Wait until a Semaphore resource becomes available.
rtos::Semaphore::Semaphore
Semaphore(int32_t count=0)
Create and Initialize a Semaphore object used for managing resources.
rtos::Semaphore::~Semaphore
~Semaphore()
Semaphore destructor.
rtos::Semaphore::acquire
void acquire()
Wait until a Semaphore resource becomes available.
MBED_DEPRECATED_SINCE
#define MBED_DEPRECATED_SINCE(D, M)
MBED_DEPRECATED("message string") Mark a function declaration as deprecated, if it used then a warnin...
Definition: mbed_toolchain.h:379
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