77 lines
2.4 KiB
C
77 lines
2.4 KiB
C
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/****************************************************************************
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* libs/libc/semaphore/sem_trywait.c
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed with
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* this work for additional information regarding copyright ownership. The
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* ASF licenses this file to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance with the
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* License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*
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****************************************************************************/
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/****************************************************************************
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* Included Files
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****************************************************************************/
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#include <nuttx/config.h>
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#include <errno.h>
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#include <nuttx/semaphore.h>
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/****************************************************************************
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* Public Functions
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****************************************************************************/
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/****************************************************************************
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* Name: sem_trywait
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*
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* Description:
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* This function locks the specified semaphore only if the semaphore is
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* currently not locked. In either case, the call returns without
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* blocking.
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*
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* Input Parameters:
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* sem - the semaphore descriptor
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*
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* Returned Value:
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* Zero (OK) on success or -1 (ERROR) if unsuccessful. If this function
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* returns -1(ERROR), then the cause of the failure will be reported in
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* errno variable as:
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*
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* EINVAL - Invalid attempt to get the semaphore
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* EAGAIN - The semaphore is not available.
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*
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****************************************************************************/
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int sem_trywait(FAR sem_t *sem)
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{
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int ret;
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if (sem == NULL)
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{
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set_errno(EINVAL);
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return ERROR;
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}
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/* Let nxsem_trywait do the real work */
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ret = nxsem_trywait(sem);
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if (ret < 0)
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{
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set_errno(-ret);
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ret = ERROR;
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}
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return ret;
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}
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