Mutex.cpp

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 #include "rtos/Mutex.h"
00023 #include "rtos/Kernel.h"
00024 
00025 #include <string.h>
00026 #include "mbed_error.h"
00027 #include "mbed_assert.h"
00028 
00029 namespace rtos {
00030 
00031 Mutex::Mutex(): _count(0)
00032 {
00033     constructor();
00034 }
00035 
00036 Mutex::Mutex(const char *name)
00037 {
00038     constructor(name);
00039 }
00040 
00041 void Mutex::constructor(const char *name)
00042 {
00043     memset(&_obj_mem, 0, sizeof(_obj_mem));
00044     osMutexAttr_t attr = { 0 };
00045     attr.name = name ? name : "aplication_unnamed_mutex";
00046     attr.cb_mem = &_obj_mem;
00047     attr.cb_size = sizeof(_obj_mem);
00048     attr.attr_bits = osMutexRecursive | osMutexPrioInherit | osMutexRobust;
00049     _id = osMutexNew(&attr);
00050     MBED_ASSERT(_id);
00051 }
00052 
00053 osStatus Mutex::lock(uint32_t millisec) {
00054     osStatus status = osMutexAcquire(_id, millisec);
00055     if (osOK == status) {
00056         _count++;
00057     }
00058     return status;
00059 }
00060 
00061 bool Mutex::trylock() {
00062     return trylock_for(0);
00063 }
00064 
00065 bool Mutex::trylock_for(uint32_t millisec) {
00066     osStatus status = lock(millisec);
00067     if (status == osOK) {
00068         return true;
00069     }
00070 
00071     MBED_ASSERT(status == osErrorTimeout || status == osErrorResource);
00072 
00073     return false;
00074 }
00075 
00076 bool Mutex::trylock_until(uint64_t millisec) {
00077     uint64_t now = Kernel::get_ms_count();
00078 
00079     if (now >= millisec) {
00080         return trylock();
00081     } else if (millisec - now >= osWaitForever) {
00082         // API permits early return
00083         return trylock_for(osWaitForever - 1);
00084     } else {
00085         return trylock_for(millisec - now);
00086     }
00087 }
00088 
00089 osStatus Mutex::unlock() {
00090     _count--;
00091     return osMutexRelease(_id);
00092 }
00093 
00094 osThreadId Mutex::get_owner() {
00095     return osMutexGetOwner(_id);
00096 }
00097 
00098 Mutex::~Mutex() {
00099     osMutexDelete(_id);
00100 }
00101 
00102 }