NuttX RTOS

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3 42af7a65-404d-4744-a932-0658087f49c3

1 files changed, 181 insertions, 0 deletions

diff --git a/nuttx/sched/sched_processtimer.c b/nuttx/sched/sched_processtimer.c
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+/************************************************************
+ * sched_processtimer.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.
+ *
+ ************************************************************/
+
+/************************************************************
+ * Compilation Switches
+ ************************************************************/
+
+/************************************************************
+ * Included Files
+ ************************************************************/
+
+#include <nuttx/config.h>
+#include <sys/types.h>
+
+#if CONFIG_RR_INTERVAL > 0
+# include <sched.h>
+#endif
+
+#include "os_internal.h"
+#include "wd_internal.h"
+#include "clock_internal.h"
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/************************************************************
+ * Private Type Declarations
+ ************************************************************/
+
+/************************************************************
+ * Global Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Functions
+ ************************************************************/
+
+static inline void sched_process_timeslice(void)
+{
+#if CONFIG_RR_INTERVAL > 0
+  _TCB *rtcb;
+
+  /* Check if the currently executing task uses round robin
+   * scheduling.
+   */
+
+  rtcb = (_TCB*)g_readytorun.head;
+  if ((rtcb->flags & TCB_FLAG_ROUND_ROBIN) != 0)
+    {
+      /* Yes, check if decrementing the timeslice counter
+       * would cause the timeslice to expire
+       */
+
+      if (rtcb->timeslice <= 1)
+        {
+          /* We know we are at the head of the ready to run
+           * prioritized list.  We must be the highest priority
+           * task eligible for execution.  Check the next task
+           * in the ready to run list.  If it is the same
+           * priority, then we need to relinquish the CPU and
+           * give that task a shot.
+           */
+
+          if (rtcb->flink &&
+              rtcb->flink->sched_priority >= rtcb->sched_priority)
+            {
+              struct sched_param param;
+
+              /* Reset the timeslice */
+
+              rtcb->timeslice = CONFIG_RR_INTERVAL;
+
+              /* Just resetting the task priority to its current
+               * value.  This this will cause the task to be
+               * rescheduled behind any other tasks at the same
+               * priority.
+               */
+
+              param.sched_priority = rtcb->sched_priority;
+              (void)sched_setparam(0, &param);
+            }
+        }
+      else
+        {
+          /* Decrement the timeslice counter */
+
+          rtcb->timeslice--;
+        }
+    }
+#endif
+}
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * System Timer Hooks
+ *
+ * These are standard interfaces that are exported by the OS
+ * for use by the architecture specific logic
+ *
+ ************************************************************/
+
+/************************************************************
+ * Name:  sched_process_timer
+ *
+ * Description:
+ *   This function handles system timer events.
+ *   The timer interrupt logic itself is implemented in the
+ *   architecture specific code, but must call the following OS
+ *   function periodically -- the calling interval must be
+ *   MSEC_PER_TICK
+ *
+ * Inputs:
+ *   None
+ *
+ * Return Value:
+ *   None
+ *
+ ************************************************************/
+
+void sched_process_timer(void)
+{
+  /* Increment the system time (if in the link) */
+
+  if (clock_timer != NULL)
+    {
+      clock_timer();
+    }
+
+  /* Process watchdogs (if in the link) */
+
+  if (wd_timer != NULL)
+    {
+      wd_timer();
+    }
+
+  /* Check if the currently executing task has exceeded its
+   * timeslice.
+   */
+
+   sched_process_timeslice();
+}