110 lines
3.9 KiB
C
110 lines
3.9 KiB
C
/****************************************************************************
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* libs/libc/semaphore/sem_getvalue.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 <sys/types.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: nxsem_get_value
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*
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* Description:
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* This function updates the location referenced by 'sval' argument to
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* have the value of the semaphore referenced by 'sem' without effecting
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* the state of the semaphore. The updated value represents the actual
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* semaphore value that occurred at some unspecified time during the call,
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* but may not reflect the actual value of the semaphore when it is
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* returned to the calling task.
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*
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* If 'sem' is locked, then the object to which 'sval' points shall either
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* be zero or a negative number whose absolute value represents the number
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* of tasks waiting for the semaphore.
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*
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* Input Parameters:
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* sem - Semaphore descriptor
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* sval - Buffer by which the value is returned
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*
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* Returned Value:
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* This is an internal OS interface and should not be used by applications.
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* It follows the NuttX internal error return policy: Zero (OK) is
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* returned on success. A negated errno value is returned on failure.
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*
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****************************************************************************/
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int nxsem_get_value(FAR sem_t *sem, FAR int *sval)
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{
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if (sem != NULL && sval != NULL)
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{
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*sval = sem->semcount;
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return OK;
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}
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return -EINVAL;
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}
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/****************************************************************************
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* Name: sem_getvalue
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*
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* Description:
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* This function updates the location referenced by 'sval' argument to
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* have the value of the semaphore referenced by 'sem' without effecting
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* the state of the semaphore. The updated value represents the actual
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* semaphore value that occurred at some unspecified time during the call,
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* but may not reflect the actual value of the semaphore when it is
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* returned to the calling task.
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*
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* If 'sem' is locked, then the object to which 'sval' points shall either
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* be zero or a negative number whose absolute value represents the number
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* of tasks waiting for the semaphore.
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*
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* Input Parameters:
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* sem - Semaphore descriptor
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* sval - Buffer by which the value is returned
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*
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* This returns zero (OK) if successful. Otherwise, -1 (ERROR) is
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* returned and the errno value is set appropriately.
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*
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****************************************************************************/
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int sem_getvalue(FAR sem_t *sem, FAR int *sval)
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{
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int ret;
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ret = nxsem_get_value(sem, sval);
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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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