mirror of https://github.com/ARMmbed/mbed-os.git
133 lines
4.7 KiB
C++
133 lines
4.7 KiB
C++
/* mbed Microcontroller Library
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* Copyright (c) 2006-2019 ARM Limited
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* SPDX-License-Identifier: MIT
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
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* SOFTWARE.
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*/
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#ifndef SEMAPHORE_H
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#define SEMAPHORE_H
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#include <stdint.h>
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#include "rtos/mbed_rtos_types.h"
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#include "rtos/mbed_rtos1_types.h"
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#include "rtos/mbed_rtos_storage.h"
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#include "platform/mbed_toolchain.h"
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#include "platform/NonCopyable.h"
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namespace rtos {
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/** \addtogroup rtos-public-api */
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/** @{*/
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/**
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* \defgroup rtos_Semaphore Semaphore class
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* @{
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*/
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/** The Semaphore class is used to manage and protect access to a set of shared resources.
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*
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* @note
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* Memory considerations: The semaphore control structures will be created on current thread's stack, both for the mbed OS
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* and underlying RTOS objects (static or dynamic RTOS memory pools are not being used).
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*/
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class Semaphore : private mbed::NonCopyable<Semaphore> {
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public:
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/** Create and Initialize a Semaphore object used for managing resources.
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@param count number of available resources; maximum index value is (count-1). (default: 0).
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@note You cannot call this function from ISR context.
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*/
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Semaphore(int32_t count = 0);
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/** Create and Initialize a Semaphore object used for managing resources.
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@param count number of available resources
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@param max_count maximum number of available resources
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@note You cannot call this function from ISR context.
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*/
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Semaphore(int32_t count, uint16_t max_count);
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/** Wait until a Semaphore resource becomes available.
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@note You cannot call this function from ISR context.
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*/
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void acquire();
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/** Try to acquire a Semaphore resource, and return immediately
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@return true if a resource was acquired, false otherwise.
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@note equivalent to try_acquire_for(0)
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@note You may call this function from ISR context.
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*/
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bool try_acquire();
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/** Wait until a Semaphore resource becomes available.
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@param millisec timeout value.
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@return true if a resource was acquired, false otherwise.
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@note You may call this function from ISR context if the millisec parameter is set to 0.
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*/
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bool try_acquire_for(uint32_t millisec);
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/** Wait until a Semaphore resource becomes available.
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@param millisec absolute timeout time, referenced to Kernel::get_ms_count()
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@return true if a resource was acquired, false otherwise.
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@note the underlying RTOS may have a limit to the maximum wait time
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due to internal 32-bit computations, but this is guaranteed to work if the
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wait is <= 0x7fffffff milliseconds (~24 days). If the limit is exceeded,
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the acquire attempt will time out earlier than specified.
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@note You cannot call this function from ISR context.
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*/
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bool try_acquire_until(uint64_t millisec);
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/** Release a Semaphore resource that was obtain with Semaphore::acquire.
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@return status code that indicates the execution status of the function:
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@a osOK the token has been correctly released.
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@a osErrorResource the maximum token count has been reached.
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@a osErrorParameter internal error.
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@note You may call this function from ISR context.
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*/
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osStatus release(void);
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/** Semaphore destructor
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*
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* @note You cannot call this function from ISR context.
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*/
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~Semaphore();
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private:
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void constructor(int32_t count, uint16_t max_count);
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#if MBED_CONF_RTOS_PRESENT
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int32_t _wait(uint32_t millisec);
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osSemaphoreId_t _id;
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mbed_rtos_storage_semaphore_t _obj_mem;
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#else
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static bool semaphore_available(void *);
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int32_t _count;
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uint16_t _max_count;
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#endif
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};
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/** @}*/
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/** @}*/
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}
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#endif
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