diff options
author | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2007-02-17 23:21:28 +0000 |
---|---|---|
committer | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2007-02-17 23:21:28 +0000 |
commit | e3940eb2080711edac189cca3f642ee89dc215f2 (patch) | |
tree | 1c390958fae49e34dce698b175487e6d4681e540 /nuttx/sched/sem_getvalue.c | |
parent | 2223612deb2cc6322992f8595b6d6f86fcb53ae1 (diff) | |
download | px4-nuttx-e3940eb2080711edac189cca3f642ee89dc215f2.tar.gz px4-nuttx-e3940eb2080711edac189cca3f642ee89dc215f2.tar.bz2 px4-nuttx-e3940eb2080711edac189cca3f642ee89dc215f2.zip |
NuttX RTOS
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3 42af7a65-404d-4744-a932-0658087f49c3
Diffstat (limited to 'nuttx/sched/sem_getvalue.c')
-rw-r--r-- | nuttx/sched/sem_getvalue.c | 112 |
1 files changed, 112 insertions, 0 deletions
diff --git a/nuttx/sched/sem_getvalue.c b/nuttx/sched/sem_getvalue.c new file mode 100644 index 000000000..b7dd201c7 --- /dev/null +++ b/nuttx/sched/sem_getvalue.c @@ -0,0 +1,112 @@ +/************************************************************ + * sem_getvalue.c + * + * Copyright (C) 2007 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <spudmonkey@racsa.co.cr> + * + * 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 Gregory Nutt 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 <sys/types.h> +#include <semaphore.h> +#include "sem_internal.h" + +/************************************************************ + * Compilation Switches + ************************************************************/ + +/************************************************************ + * Definitions + ************************************************************/ + +/************************************************************ + * Private Type Declarations + ************************************************************/ + +/************************************************************ + * Global Variables + ************************************************************/ + +/************************************************************ + * Private Variables + ************************************************************/ + +/************************************************************ + * Private Functions + ************************************************************/ + +/************************************************************ + * Public Functions + ************************************************************/ + +/************************************************************ + * Function: sem_getvalue + * + * Description: + * This function updates the location referenced by sval + * argument to have the value of the semaphore referenced + * by sem without effecting the state of the semaphore. + * The updated value represents the actual semaphore value + * that occurred at some unspecified time during the call, + * but may not reflect the actual value of the semaphore + * when it is returned to the calling task. + * + * If sem is locked, the value return by sem_getvalue() + * will either be zero or a negative number whose absolute + * value represents the number of tasks waiting for the + * semaphore. + * + * Parameters: + * sem - Semaphore descriptor + * sval - Buffer by which the value is returned + * + * Return Value: + * 0 (OK), or -1 (ERROR) if unsuccessful + * + * Assumptions: + * + ************************************************************/ + +int sem_getvalue(sem_t *sem, int *sval) +{ + int ret = ERROR; + + if (sem && sval) + { + *sval = sem->semcount; + ret = OK; + } + + return ret; +} + |