c9bdadd541
This moves all the public POSIX semaphore functions into libc and with this most of the user-space logic is also moved; namely cancel point and errno handling. This also removes the need for the _SEM_XX macros used to differentiate which API is used per user-/kernel mode. Such macros are henceforth unnecessary.
85 lines
2.8 KiB
C
85 lines
2.8 KiB
C
/****************************************************************************
|
|
* libs/libc/semaphore/sem_post.c
|
|
*
|
|
* Licensed to the Apache Software Foundation (ASF) under one or more
|
|
* contributor license agreements. See the NOTICE file distributed with
|
|
* this work for additional information regarding copyright ownership. The
|
|
* ASF licenses this file to you under the Apache License, Version 2.0 (the
|
|
* "License"); you may not use this file except in compliance with the
|
|
* License. You may obtain a copy of the License at
|
|
*
|
|
* http://www.apache.org/licenses/LICENSE-2.0
|
|
*
|
|
* Unless required by applicable law or agreed to in writing, software
|
|
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
|
|
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
|
|
* License for the specific language governing permissions and limitations
|
|
* under the License.
|
|
*
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Included Files
|
|
****************************************************************************/
|
|
|
|
#include <nuttx/config.h>
|
|
|
|
#include <errno.h>
|
|
|
|
#include <nuttx/semaphore.h>
|
|
|
|
/****************************************************************************
|
|
* Public Functions
|
|
****************************************************************************/
|
|
|
|
/****************************************************************************
|
|
* Name: sem_post
|
|
*
|
|
* Description:
|
|
* When a task has finished with a semaphore, it will call sem_post().
|
|
* This function unlocks the semaphore referenced by sem by performing the
|
|
* semaphore unlock operation on that semaphore.
|
|
*
|
|
* If the semaphore value resulting from this operation is positive, then
|
|
* no tasks were blocked waiting for the semaphore to become unlocked; the
|
|
* semaphore is simply incremented.
|
|
*
|
|
* If the value of the semaphore resulting from this operation is zero,
|
|
* then one of the tasks blocked waiting for the semaphore shall be
|
|
* allowed to return successfully from its call to nxsem_wait().
|
|
*
|
|
* Input Parameters:
|
|
* sem - Semaphore descriptor
|
|
*
|
|
* Returned Value:
|
|
* This function is a standard, POSIX application interface. It will
|
|
* return zero (OK) if successful. Otherwise, -1 (ERROR) is returned and
|
|
* the errno value is set appropriately.
|
|
*
|
|
* Assumptions:
|
|
* This function may be called from an interrupt handler.
|
|
*
|
|
****************************************************************************/
|
|
|
|
int sem_post(FAR sem_t *sem)
|
|
{
|
|
int ret;
|
|
|
|
/* Make sure we were supplied with a valid semaphore. */
|
|
|
|
if (sem == NULL)
|
|
{
|
|
set_errno(EINVAL);
|
|
return ERROR;
|
|
}
|
|
|
|
ret = nxsem_post(sem);
|
|
if (ret < 0)
|
|
{
|
|
set_errno(-ret);
|
|
ret = ERROR;
|
|
}
|
|
|
|
return ret;
|
|
}
|