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diff --git a/nuttx/sched/sched_addreadytorun.c b/nuttx/sched/sched_addreadytorun.c
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+/****************************************************************************
+ * sched/sched_addreadytorun.c
+ *
+ *   Copyright (C) 2007-2009 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 <stdbool.h>
+#include <queue.h>
+#include <assert.h>
+
+#include "os_internal.h"
+
+/****************************************************************************
+ * Pre-processor Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Function Prototypes
+ ****************************************************************************/
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name:  sched_addreadytorun
+ *
+ * Description:
+ *   This function adds a TCB to the ready to run
+ *   list.  If the currently active task has preemption disabled
+ *   and the new TCB would cause this task to be preempted, the
+ *   new task is added to the g_pendingtasks list instead.  The
+ *   pending tasks will be made ready-to-run when preemption
+ *   is unlocked.
+ *
+ * Inputs:
+ *   btcb - Points to the blocked TCB that is ready-to-run
+ *
+ * Return Value:
+ *   true if the currently active task (the head of the 
+ *     g_readytorun list) has changed.
+ *
+ * Assumptions:
+ * - The caller has established a critical section before
+ *   calling this function (calling sched_lock() first is NOT
+ *   a good idea -- use irqsave()).
+ * - The caller has already removed the input rtcb from
+ *   whatever list it was in.
+ * - The caller handles the condition that occurs if the
+ *   the head of the g_readytorun list is changed.
+ *
+ ****************************************************************************/
+
+bool sched_addreadytorun(FAR _TCB *btcb)
+{
+  FAR _TCB *rtcb = (FAR _TCB*)g_readytorun.head;
+  bool ret;
+
+  /* Check if pre-emption is disabled for the current running task and if
+   * the new ready-to-run task  would cause the current running task to be
+   * preempted.
+   */
+
+  if (rtcb->lockcount && rtcb->sched_priority < btcb->sched_priority)
+    {
+      /* Yes.  Preemption would occur!  Add the new ready-to-run task to the
+       * g_pendingtasks task list for now.
+       */
+
+      sched_addprioritized(btcb, (FAR dq_queue_t*)&g_pendingtasks);
+      btcb->task_state = TSTATE_TASK_PENDING;
+      ret = false;
+    }
+
+  /* Otherwise, add the new task to the g_readytorun task list */
+
+  else if (sched_addprioritized(btcb, (FAR dq_queue_t*)&g_readytorun))
+    {
+      /* Information the instrumentation logic that we are switching tasks */
+
+      sched_note_switch(rtcb, btcb);
+
+      /* The new btcb was added at the head of the g_readytorun list.  It
+       * is now to new active task!
+       */
+
+      ASSERT(!rtcb->lockcount && btcb->flink != NULL);
+
+      btcb->task_state = TSTATE_TASK_RUNNING;
+      btcb->flink->task_state = TSTATE_TASK_READYTORUN;
+      ret = true;
+    }
+  else
+    {
+      /* The new btcb was added in the middle of the g_readytorun list */
+
+      btcb->task_state = TSTATE_TASK_READYTORUN;
+      ret = false;
+    }
+
+  return ret;
+}