Resync new repository with old repo r5166

git-svn-id: http://svn.code.sf.net/p/nuttx/code/trunk@5153 42af7a65-404d-4744-a932-0658087f49c3
2026-11-01 06:21:36 +08:00 · 2012-09-17 18:18:44 +00:00
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+/****************************************************************************
+ * lib/semaphore/sem_getvalue.c
+ *
+ *   Copyright (C) 2007-2009, 2011 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 <sys/types.h>
+#include <semaphore.h>
+#include <errno.h>
+
+/****************************************************************************
+ * 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(FAR sem_t *sem, FAR int *sval)
+{
+  if (sem && sval)
+    {
+      *sval = sem->semcount;
+      return OK;
+    }
+  else
+    {
+      set_errno(EINVAL);
+	  return ERROR;
+    }
+}