83cdb0c552
libc/semaphore: Add nxsem_getvalue() which is identical to sem_getvalue() except that it never modifies the errno variable. Changed all references to sem_getvalue in the OS to nxsem_getvalue().
sched/semaphore: Rename all internal private functions from sem_xyz to nxsem_xyz. The sem_ prefix is (will be) reserved only for the application semaphore interfaces.
libc/semaphore: Add nxsem_init() which is identical to sem_init() except that it never modifies the errno variable. Changed all references to sem_init in the OS to nxsem_init().
sched/semaphore: Rename sem_tickwait() to nxsem_tickwait() so that it is clear this is an internal OS function.
sched/semaphoate: Rename sem_reset() to nxsem_reset() so that it is clear this is an internal OS function.
126 lines
4.7 KiB
C
126 lines
4.7 KiB
C
/****************************************************************************
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* libc/semaphore/sem_getvalue.c
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*
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* Copyright (C) 2007-2009, 2011 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <gnutt@nuttx.org>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name NuttX nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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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
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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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 <semaphore.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_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, the value return by nxsem_getvalue() will either be
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* 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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* 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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* Return 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_getvalue(FAR sem_t *sem, FAR int *sval)
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{
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if (sem && sval)
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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, the value return by sem_getvalue() will either be
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* 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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* 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_getvalue(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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