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 "cmsis_os2.h"
00027 #include "mbed_rtos1_types.h"
00028 #include "mbed_rtos_storage.h"
00029 #include "platform/NonCopyable.h"
00030 
00031 namespace rtos {
00032 /** \addtogroup rtos */
00033 /** @{*/
00034 
00035 /** The Semaphore class is used to manage and protect access to a set of shared resources.
00036  *
00037  * @note
00038  * Memory considerations: The semaphore control structures will be created on current thread's stack, both for the mbed OS
00039  * and underlying RTOS objects (static or dynamic RTOS memory pools are not being used).
00040  */
00041 class Semaphore : private mbed::NonCopyable<Semaphore> {
00042 public:
00043     /** Create and Initialize a Semaphore object used for managing resources.
00044       @param count      number of available resources; maximum index value is (count-1). (default: 0).
00045     */
00046     Semaphore(int32_t count=0);
00047 
00048     /** Create and Initialize a Semaphore object used for managing resources.
00049       @param  count     number of available resources
00050       @param  max_count maximum number of available resources
00051     */
00052     Semaphore(int32_t count, uint16_t max_count);
00053 
00054     /** Wait until a Semaphore resource becomes available.
00055       @param   millisec  timeout value or 0 in case of no time-out. (default: osWaitForever).
00056       @return  number of available tokens, before taking one; or -1 in case of incorrect parameters
00057     */
00058     int32_t wait(uint32_t millisec=osWaitForever);
00059 
00060     /** Release a Semaphore resource that was obtain with Semaphore::wait.
00061       @return status code that indicates the execution status of the function:
00062               @a osOK the token has been correctly released.
00063               @a osErrorResource the maximum token count has been reached.
00064               @a osErrorParameter internal error.
00065     */
00066     osStatus release(void);
00067 
00068     ~Semaphore();
00069 
00070 private:
00071     void constructor(int32_t count, uint16_t max_count);
00072 
00073     osSemaphoreId_t               _id;
00074     osSemaphoreAttr_t             _attr;
00075     mbed_rtos_storage_semaphore_t _obj_mem;
00076 };
00077 
00078 }
00079 #endif
00080 
00081 /** @}*/