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/* ----------------------------------------------------------------------------
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* Copyright (c) Huawei Technologies Co., Ltd. 2013-2020. All rights reserved.
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* Description: Semaphore HeadFile
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* Author: Huawei LiteOS Team
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* Create: 2013-01-01
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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* 1. Redistributions of source code must retain the above copyright notice, this list of
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* conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice, this list
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* of conditions and the following disclaimer in the documentation and/or other materials
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* provided with the distribution.
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* 3. Neither the name of the copyright holder nor the names of its contributors may be used
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* to endorse or promote products derived from this software without specific prior written
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* permission.
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
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* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR
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* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
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* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
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* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
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* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
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* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF
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* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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* --------------------------------------------------------------------------- */
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/*这段代码实现了对信号量操作的基本功能，包括创建、删除、请求和释放信号量，并对可能出现的错误情况进行了定义和说明。*/
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/**
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* @defgroup los_sem Semaphore
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* @ingroup kernel
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*/
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#ifndef _LOS_SEM_H
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#define _LOS_SEM_H
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#include "los_base.h"
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#include "los_err.h"
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#include "los_list.h"
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#include "los_task.h"
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#ifdef __cplusplus
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#if __cplusplus
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extern "C" {
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#endif /* __cplusplus */
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#endif /* __cplusplus */
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/**
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* @ingroup los_sem
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* Max count of counting semaphores
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*/
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#define LOS_SEM_COUNT_MAX 0xFFFE/*计数信号量的最大值*/
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/**
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* @ingroup los_sem 该宏定义属于信号量模块。
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* Semaphore error code: The memory is insufficient. 内存不足
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*
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* Value: 0x02000700. 以十六进制表示
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*
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* Solution: Allocate more memory. 解决该错误的方法为分配更多的内存。
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*/
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#define LOS_ERRNO_SEM_NO_MEMORY LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x00)/*定义一个信号量（Semaphore）的错误码，表示内存不足
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/**
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* @ingroup los_sem
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* Semaphore error code: Invalid parameter.
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*
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* Value: 0x02000701.
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*
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* Solution: Change the passed-in invalid parameter value to a valid value.
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*/
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#define LOS_ERRNO_SEM_INVALID LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x01)
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/**
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* @ingroup los_sem 该宏定义属于信号量模块。
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* Semaphore error code: Null pointer. 该错误码的含义为参数无效。
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*
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* Value: 0x02000702. 以十六进制表示
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*
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* Solution: Change the passed-in null pointer to a valid non-null pointer. 解决该错误的方法：将传入的无效参数值更改为有效值
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*/
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#define LOS_ERRNO_SEM_PTR_NULL LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x02)/*这段代码定义了一个信号量模块的错误码，表示参数无效
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/**
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* @ingroup los_sem
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* Semaphore error code: No semaphore control structure is available.
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*
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* Value: 0x02000703.
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*
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* Solution: Perform corresponding operations based on the requirements in the code context.解决该错误的方法：根据代码上下文的要求执行相应的操作。
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*/
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#define LOS_ERRNO_SEM_ALL_BUSY LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x03)/*定义了一个信号量模块的错误码，表示没有可用的信号量控制结构*/
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/**
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* @ingroup los_sem
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* Semaphore error code: Invalid parameter that specifies the timeout interval.
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*
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* Value: 0x02000704.
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*
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* Solution: Change the passed-in parameter value to a valid nonzero value.解决该错误的方法：将传入的参数值更改为有效的非零值
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*/
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#define LOS_ERRNO_SEM_UNAVAILABLE LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x04)/*定义了一个信号量模块的错误码，表示指定的超时时间参数无效*/
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/**
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* @ingroup los_sem
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* Semaphore error code: The API is called during an interrupt, which is forbidden.
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*
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* Value: 0x02000705.
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*
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* Solution: Do not call the API during an interrupt.解决该错误的方法a:不要在中断期间调用该API
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*/
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#define LOS_ERRNO_SEM_PEND_INTERR LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x05)/*定义了一个信号量模块的错误码，表示在中断期间调用了该API，这是被禁止的*/
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/**
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* @ingroup los_sem
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* Semaphore error code: The task is unable to request a semaphore because task scheduling is locked.
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*
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* Value: 0x02000706.
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*
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* Solution: Do not call LOS_SemPend when task scheduling is locked.解决该错误的方法：在任务调度被锁定时不要调用LOS_SemPend函数
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*/
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#define LOS_ERRNO_SEM_PEND_IN_LOCK LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x06)/*定义了一个信号量模块的错误码，表示由于任务调度被锁定，任务无法请求信号量*/
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/**
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* @ingroup los_sem
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* Semaphore error code: The request for a semaphore times out.
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*
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* Value: 0x02000707.
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*
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* Solution: Change the passed-in parameter value to the value within the valid range.解决该错误的方法：将传入的参数值更改为有效范围内的值。
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*/
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#define LOS_ERRNO_SEM_TIMEOUT LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x07)/*定义了一个信号量模块的错误码，表示请求信号量超时*/
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/**
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* @ingroup los_sem
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* Semaphore error code: The times of semaphore release exceed the maximum times permitted.
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*
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* Value: 0x02000708.
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*
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* Solution: Perform corresponding operations based on the requirements in the code context.解决该错误的方法：根据代码上下文的要求执行相应的操作。
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*/
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#define LOS_ERRNO_SEM_OVERFLOW LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x08)/*定义了一个信号量模块的错误码，表示信号量释放的次数超过了允许的最大次数
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/**
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* @ingroup los_sem
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* Semaphore error code: The queue of the tasks that are waiting on the semaphore control
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* structure is not null.
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*
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* Value: 0x02000709.
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*
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* Solution: Delete the semaphore after awaking all tasks that are waiting on the semaphore.解决该错误的方法，即在唤醒等待信号量的所有任务后删除信号量
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*/
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#define LOS_ERRNO_SEM_PENDED LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x09)/*定义了一个信号量模块的错误码，表示等待信号量的任务队列不为空*/
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/**
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* @ingroup los_sem
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* Semaphore error code: The API is called in system-level callback, which is forbidden.
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* old usage: The API is called in software timer callback, which is forbidden (LOS_ERRNO_SEM_PEND_SWTERR).
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*
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* Value: 0x0200070A.
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*
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* Solution: Do not call the API in the system-level callback.解决该错误的方法，即不要在系统级回调中调用该API。
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* @deprecated This error code is obsolete since LiteOS 5.0.0.该错误码自LiteOS 5.0.0版本起已经过时。
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*/
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#define LOS_ERRNO_SEM_PEND_IN_SYSTEM_TASK LOS_ERRNO_OS_ERROR(LOS_MOD_SEM, 0x0A)/*定义了一个信号量模块的错误码，表示在系统级回调中调用了该API，这是被禁止的*/
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/**
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* @ingroup los_sem
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* @brief Create a semaphore.
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*
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* @par Description:
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* This API is used to create a semaphore control structure according to the initial number of available semaphores
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* specified by count and return the ID of this semaphore control structure.
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* @attention
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* None.
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*
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* @param count [IN] Initial number of available semaphores. The value range is [0, LOS_SEM_COUNT_MAX).
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* @param semHandle [OUT] ID of the semaphore control structure that is initialized.
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*
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* @retval #LOS_ERRNO_SEM_PTR_NULL The passed-in semHandle value is NULL.
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* @retval #LOS_ERRNO_SEM_OVERFLOW The passed-in count value is greater than the maximum number of available
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* semaphores.
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* @retval #LOS_ERRNO_SEM_ALL_BUSY No semaphore control structure is available.
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* @retval #LOS_OK The semaphore is successfully created.
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* @par Dependency:
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* <ul><li>los_sem.h: the header file that contains the API declaration.</li></ul>
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* @see LOS_SemDelete | LOS_BinarySemCreate
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* @since Huawei LiteOS V100R001C00
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*/
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extern UINT32 LOS_SemCreate(UINT16 count, UINT32 *semHandle);/*这段代码声明了一个函数LOS_SemCreate，用于创建信号量。该函数根据传入的初始可用信号量数量，
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创建一个信号量控制结构，并返回该信号量控制结构的ID。函数的返回值包括多种情况，如传入的参数为空指针、传入的初始可用信号量数量超过最大数量、没有可用的信号量控制结构等。*/
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/**
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* @ingroup los_sem
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* @brief Create a binary semaphore.
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*
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* @par Description:
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* This API is used to create a binary semaphore control structure according to the initial number of
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* available semaphores specified by count and return the ID of this semaphore control structure.
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* @attention
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* None.
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*
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* @param count [IN] Initial number of available semaphores. The value range is [0, 1].
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* @param semHandle [OUT] ID of the semaphore control structure that is initialized.
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*
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* @retval #LOS_ERRNO_SEM_PTR_NULL The passed-in semHandle value is NULL.
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* @retval #LOS_ERRNO_SEM_OVERFLOW The passed-in count value is greater than the maximum number of
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* available semaphores.
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* @retval #LOS_ERRNO_SEM_ALL_BUSY No semaphore control structure is available.
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* @retval #LOS_OK The semaphore is successfully created.
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* @par Dependency:
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* <ul><li>los_sem.h: the header file that contains the API declaration.</li></ul>
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* @see LOS_SemCreate | LOS_SemDelete
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* @since Huawei LiteOS V100R001C00
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*/
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extern UINT32 LOS_BinarySemCreate(UINT16 count, UINT32 *semHandle);/*声明了一个函数原型 LOS_BinarySemCreate，用于创建一个二进制信号量。*/
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/**
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* @ingroup los_sem
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* @brief Delete a semaphore.
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*
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* @par Description:
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* This API is used to delete a semaphore control structure that has an ID specified by semHandle.
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* @attention
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* The specified sem id must be created first before deleting it.
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*
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* @param semHandle [IN] ID of the semaphore control structure to be deleted. The ID of the semaphore
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* control structure is obtained from semaphore creation.
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*
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* @retval #LOS_ERRNO_SEM_INVALID The passed-in semHandle value is invalid.
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* @retval #LOS_ERRNO_SEM_PENDED The queue of the tasks that are waiting on the semaphore control structure is
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* not null.
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* @retval #LOS_OK The semaphore control structure is successfully deleted.
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* @par Dependency:
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* <ul><li>los_sem.h: the header file that contains the API declaration.</li></ul>
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* @see LOS_SemCreate | LOS_BinarySemCreate
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* @since Huawei LiteOS V100R001C00
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*/
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extern UINT32 LOS_SemDelete(UINT32 semHandle);/*这段代码定义了一个函数LOS_SemDelete，用于删除一个信号量的控制结构*/
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/**
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* @ingroup los_sem
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* @brief Request a semaphore.
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*
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* @par Description:
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* This API is used to request a semaphore based on the semaphore control structure ID specified by semHandle and the
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* parameter that specifies the timeout period.
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* @attention
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* <ul>
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* <li>Do not pend sem during an interrupt.</li>
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* <li>Do not pend sem in a system task, such as idle or swtmr task.</li>
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* <li>The specified sem id must be created first. </li>
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* <li>Do not recommend to use this API in software timer callback. </li>
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* </ul>
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*
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* @param semHandle [IN] ID of the semaphore control structure to be requested. The ID of the semaphore control
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* structure is obtained from semaphore creation.
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* @param timeout [IN] Timeout interval for waiting on the semaphore. The value range is [0, 0xFFFFFFFF].
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* If the value is set to 0, the semaphore is not waited on. If the value is set to 0xFFFFFFFF,
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* the semaphore is waited on forever(unit: Tick).
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*
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* @retval #LOS_ERRNO_SEM_INVALID The passed-in semHandle value is invalid.
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* @retval #LOS_ERRNO_SEM_UNAVAILABLE There is no available semaphore resource.
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* @retval #LOS_ERRNO_SEM_PEND_INTERR The API is called during an interrupt, which is forbidden.
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* @retval #LOS_ERRNO_SEM_PEND_IN_LOCK The task is unable to request a semaphore because task scheduling
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* is locked.
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* @retval #LOS_ERRNO_SEM_PEND_IN_SYSTEM_TASK The API is called in a system task, such as idle task or software
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* timer, which is forbidden.
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* @retval #LOS_ERRNO_SEM_TIMEOUT The request for the semaphore times out.
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* @retval #LOS_OK The semaphore request succeeds.
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* @par Dependency:
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* <ul><li>los_sem.h: the header file that contains the API declaration.</li></ul>
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* @see LOS_SemPost | LOS_SemCreate | LOS_BinarySemCreate
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* @since Huawei LiteOS V100R001C00
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*/
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extern UINT32 LOS_SemPend(UINT32 semHandle, UINT32 timeout);/*该函数用于请求一个信号量
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通过semHandle参数指定要请求的信号量控制结构的ID，该ID是在信号量创建时获得的。
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timeout参数指定等待信号量的超时时间，如果timeout值为0，表示不会等待信号量。如果timeout值为0xFFFFFFFF，表示会一直等待信号量。超时时间单位为Tick。
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函数返回值为操作结果：
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若返回值为LOS_ERRNO_SEM_INVALID，表示传入的semHandle值无效。
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若返回值为LOS_ERRNO_SEM_UNAVAILABLE，表示没有可用的信号量资源。
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若返回值为LOS_ERRNO_SEM_PEND_INTERR，表示在中断 [Something went wrong, please try again later.]
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*/
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/**
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* @ingroup los_sem
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* @brief Release a semaphore.
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*
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* @par Description:
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* This API is used to release a semaphore that has a semaphore control structure ID specified by semHandle.
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* @attention
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* The specified sem id must be created first.
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*
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* @param semHandle [IN] ID of the semaphore control structure to be released.The ID of the semaphore control
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* structure is obtained from semaphore creation.
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*
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* @retval #LOS_ERRNO_SEM_INVALID The passed-in semHandle value is invalid.
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* @retval #LOS_ERRNO_SEM_OVERFLOW The times of semaphore release exceed the maximum times permitted.
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* @retval #LOS_OK The semaphore is successfully released.
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* @par Dependency:
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* <ul><li>los_sem.h: the header file that contains the API declaration.</li></ul>
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* @see LOS_SemPend | LOS_SemCreate | LOS_BinarySemCreate
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* @since Huawei LiteOS V100R001C00
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*/
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extern UINT32 LOS_SemPost(UINT32 semHandle);/*这段代码定义了一个函数LOS_SemPost，用于释放一个信号量*/
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/*LOS_SemPost用于释放由semHandle指定的信号量控制结构。
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若释放前没有先创建指定的信号量，则会返回LOS_ERRNO_SEM_INVALID。
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若信号量释放的次数超过允许的最大次数，则会返回LOS_ERRNO_SEM_OVERFLOW。
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若成功释放信号量，则会返回LOS_OK。
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此函数依赖于LOS_SemPend、LOS_SemCreate和LOS_BinarySemCreate函数。*/
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#ifdef __cplusplus
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#if __cplusplus
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}
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#endif /* __cplusplus */
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#endif /* __cplusplus */
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#endif /* _LOS_SEM_H */
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