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108 lines
4.2 KiB
108 lines
4.2 KiB
/**************************************************************************** |
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* lib/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 <spudmonkey@racsa.co.cr> |
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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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/**************************************************************************** |
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* Definitions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Type Declarations |
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****************************************************************************/ |
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/**************************************************************************** |
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* Global Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Variables |
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****************************************************************************/ |
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/**************************************************************************** |
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* Private Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Public Functions |
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****************************************************************************/ |
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/**************************************************************************** |
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* Function: 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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* Return Value: |
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* 0 (OK), or -1 (ERROR) if unsuccessful |
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* |
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* Assumptions: |
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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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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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else |
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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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}
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