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_os.h"
00027 
00028 namespace rtos {
00029 
00030 /** The Semaphore class is used to manage and protect access to a set of shared resources. */
00031 class Semaphore {
00032 public:
00033     /** Create and Initialize a Semaphore object used for managing resources.
00034       @param number of available resources; maximum index value is (count-1).
00035     */
00036     Semaphore(int32_t count);
00037 
00038     /** Wait until a Semaphore resource becomes available.
00039       @param   millisec  timeout value or 0 in case of no time-out. (default: osWaitForever).
00040       @return  number of available tokens, or -1 in case of incorrect parameters
00041     */
00042     int32_t wait(uint32_t millisec=osWaitForever);
00043 
00044     /** Release a Semaphore resource that was obtain with Semaphore::wait.
00045       @return  status code that indicates the execution status of the function.
00046     */
00047     osStatus release(void);
00048 
00049     ~Semaphore();
00050 
00051 private:
00052     osSemaphoreId _osSemaphoreId;
00053     osSemaphoreDef_t _osSemaphoreDef;
00054 #ifdef CMSIS_OS_RTX
00055     uint32_t _semaphore_data[2];
00056 #endif
00057 };
00058 
00059 }
00060 #endif