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/****************************************************************************
* nuttx/graphics/nxconsole/nxcon_sem.c
*
* Copyright (C) 2012 Gregory Nutt. All rights reserved.
* Author: Gregory Nutt <gnutt@nuttx.org>
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
* 3. Neither the name NuttX nor the names of its contributors may be
* used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*
****************************************************************************/
/****************************************************************************
* Included Files
****************************************************************************/
#include <nuttx/config.h>
#include <unistd.h>
#include <semaphore.h>
#include <assert.h>
#include <errno.h>
#include "nxcon_internal.h"
#ifdef CONFIG_DEBUG
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Function Prototypes
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: nxcon_semwait and nxcon_sempost
*
* Description:
* If debug is on, then lower level code may attempt console output while
* we are doing console output! In this case, we will toss the nested
* output to avoid deadlocks and infinite loops.
*
* Input Parameters:
* priv - Driver data structure
*
* Returned Value:
*
*
****************************************************************************/
int nxcon_semwait(FAR struct nxcon_state_s *priv)
{
pid_t me;
int ret;
/* Does I already hold the semaphore */
me = getpid();
if (priv->holder != me)
{
/* No.. then wait until the thread that does hold it is finished with it */
ret = sem_wait(&priv->exclsem);
if (ret == OK)
{
/* No I hold the semaphore */
priv->holder = me;
}
return ret;
}
/* Abort, abort, abort! I have been re-entered */
set_errno(EBUSY);
return ERROR;
}
int nxcon_sempost(FAR struct nxcon_state_s *priv)
{
pid_t me = getpid();
/* Make sure that I really hold the semaphore */
ASSERT(priv->holder == me);
/* Then let go of it */
priv->holder = NO_HOLDER;
return sem_post(&priv->exclsem);
}
#endif /* CONFIG_DEBUG */
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