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Semaphore.h
00001 /* mbed Microcontroller Library 00002 * Copyright (c) 2006-2012 ARM Limited 00003 * 00004 * Permission is hereby granted, free of charge, to any person obtaining a copy 00005 * of this software and associated documentation files (the "Software"), to deal 00006 * in the Software without restriction, including without limitation the rights 00007 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell 00008 * copies of the Software, and to permit persons to whom the Software is 00009 * furnished to do so, subject to the following conditions: 00010 * 00011 * The above copyright notice and this permission notice shall be included in 00012 * all copies or substantial portions of the Software. 00013 * 00014 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR 00015 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, 00016 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE 00017 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER 00018 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, 00019 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 00020 * SOFTWARE. 00021 */ 00022 #ifndef SEMAPHORE_H 00023 #define SEMAPHORE_H 00024 00025 #include <stdint.h> 00026 #include "mbed_rtos_types.h" 00027 #include "mbed_rtos1_types.h" 00028 #include "mbed_rtos_storage.h" 00029 #include "platform/mbed_toolchain.h" 00030 #include "platform/NonCopyable.h" 00031 00032 namespace rtos { 00033 /** \addtogroup rtos */ 00034 /** @{*/ 00035 /** 00036 * \defgroup rtos_Semaphore Semaphore class 00037 * @{ 00038 */ 00039 00040 /** The Semaphore class is used to manage and protect access to a set of shared resources. 00041 * 00042 * @note 00043 * Memory considerations: The semaphore control structures will be created on current thread's stack, both for the mbed OS 00044 * and underlying RTOS objects (static or dynamic RTOS memory pools are not being used). 00045 */ 00046 class Semaphore : private mbed::NonCopyable<Semaphore> { 00047 public: 00048 /** Create and Initialize a Semaphore object used for managing resources. 00049 @param count number of available resources; maximum index value is (count-1). (default: 0). 00050 00051 @note You cannot call this function from ISR context. 00052 */ 00053 Semaphore(int32_t count = 0); 00054 00055 /** Create and Initialize a Semaphore object used for managing resources. 00056 @param count number of available resources 00057 @param max_count maximum number of available resources 00058 00059 @note You cannot call this function from ISR context. 00060 */ 00061 Semaphore(int32_t count, uint16_t max_count); 00062 00063 /** Wait until a Semaphore resource becomes available. 00064 00065 @deprecated Do not use this function. This function has been replaced with acquire(), try_acquire() and try_acquire_for() functions. 00066 00067 @param millisec timeout value. (default: osWaitForever). 00068 @return number of available tokens, before taking one; or -1 in case of incorrect parameters 00069 00070 @note You may call this function from ISR context if the millisec parameter is set to 0. 00071 */ 00072 MBED_DEPRECATED_SINCE("mbed-os-5.13", "Replaced with acquire, try_acquire() and try_acquire_for() functions") 00073 int32_t wait(uint32_t millisec = osWaitForever); 00074 00075 /** Wait until a Semaphore resource becomes available. 00076 00077 @deprecated Do not use this function. This function has been replaced with try_acquire_until(). 00078 00079 @param millisec absolute timeout time, referenced to Kernel::get_ms_count() 00080 @return number of available tokens, before taking one; or -1 in case of incorrect parameters 00081 @note the underlying RTOS may have a limit to the maximum wait time 00082 due to internal 32-bit computations, but this is guaranteed to work if the 00083 wait is <= 0x7fffffff milliseconds (~24 days). If the limit is exceeded, 00084 the acquire attempt will time out earlier than specified. 00085 00086 @note You cannot call this function from ISR context. 00087 */ 00088 MBED_DEPRECATED_SINCE("mbed-os-5.13", "Replaced with try_acquire_until()") 00089 int32_t wait_until(uint64_t millisec); 00090 00091 /** Wait until a Semaphore resource becomes available. 00092 00093 @note You cannot call this function from ISR context. 00094 */ 00095 void acquire(); 00096 00097 /** Try to acquire a Semaphore resource, and return immediately 00098 @return true if a resource was acquired, false otherwise. 00099 @note equivalent to try_acquire_for(0) 00100 00101 @note You may call this function from ISR context. 00102 */ 00103 bool try_acquire(); 00104 00105 /** Wait until a Semaphore resource becomes available. 00106 @param millisec timeout value. 00107 @return true if a resource was acquired, false otherwise. 00108 00109 @note You may call this function from ISR context if the millisec parameter is set to 0. 00110 */ 00111 bool try_acquire_for(uint32_t millisec); 00112 00113 /** Wait until a Semaphore resource becomes available. 00114 @param millisec absolute timeout time, referenced to Kernel::get_ms_count() 00115 @return true if a resource was acquired, false otherwise. 00116 @note the underlying RTOS may have a limit to the maximum wait time 00117 due to internal 32-bit computations, but this is guaranteed to work if the 00118 wait is <= 0x7fffffff milliseconds (~24 days). If the limit is exceeded, 00119 the acquire attempt will time out earlier than specified. 00120 00121 @note You cannot call this function from ISR context. 00122 */ 00123 bool try_acquire_until(uint64_t millisec); 00124 00125 /** Release a Semaphore resource that was obtain with Semaphore::acquire. 00126 @return status code that indicates the execution status of the function: 00127 @a osOK the token has been correctly released. 00128 @a osErrorResource the maximum token count has been reached. 00129 @a osErrorParameter internal error. 00130 00131 @note You may call this function from ISR context. 00132 */ 00133 osStatus release(void); 00134 00135 /** Semaphore destructor 00136 * 00137 * @note You cannot call this function from ISR context. 00138 */ 00139 ~Semaphore(); 00140 00141 private: 00142 void constructor(int32_t count, uint16_t max_count); 00143 00144 #if MBED_CONF_RTOS_PRESENT 00145 int32_t _wait(uint32_t millisec); 00146 00147 osSemaphoreId_t _id; 00148 mbed_rtos_storage_semaphore_t _obj_mem; 00149 #else 00150 static bool semaphore_available(void *); 00151 int32_t _count; 00152 uint16_t _max_count; 00153 #endif 00154 }; 00155 /** @}*/ 00156 /** @}*/ 00157 } 00158 #endif 00159 00160
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