NuttX RTOS

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

1 files changed, 168 insertions, 0 deletions

diff --git a/nuttx/sched/sched_mergepending.c b/nuttx/sched/sched_mergepending.c
new file mode 100644
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+++ b/nuttx/sched/sched_mergepending.c
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+/************************************************************
+ * sched_mergepending.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 <queue.h>
+#include <assert.h>
+#include "os_internal.h"
+
+/************************************************************
+ * Definitions
+ ************************************************************/
+
+/************************************************************
+ * Private Type Declarations
+ ************************************************************/
+
+/************************************************************
+ * Global Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Variables
+ ************************************************************/
+
+/************************************************************
+ * Private Function Prototypes
+ ************************************************************/
+
+/************************************************************
+ * Public Functions
+ ************************************************************/
+
+/************************************************************
+ * Function: sched_mergepending
+ *
+ * Description:
+ *   This function merges the prioritized g_pendingtasks list
+ *   into the prioritized g_readytorun task list.
+ *
+ * Inputs:
+ *   None
+ *
+ * Return Value:
+ *   TRUE if the head of the g_readytorun task 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 handles the condition that occurs if the
+ *   the head of the sched_mergTSTATE_TASK_PENDINGs is changed.
+ *
+ ************************************************************/
+
+boolean sched_mergepending(void)
+{
+  _TCB *pndtcb;
+  _TCB *pndnext;
+  _TCB *rtrtcb;
+  _TCB *rtrprev;
+  boolean ret = FALSE;
+
+  /* Initialize the inner search loop */
+
+  rtrtcb = (_TCB*)g_readytorun.head;
+
+  /* Process every TCB in the g_pendingtasks list */
+
+  for (pndtcb = (_TCB*)g_pendingtasks.head; pndtcb; pndtcb = pndnext)
+    {
+      pndnext = pndtcb->flink;
+
+      /* Search the g_readytorun list to find the location to insert the 
+       * new pndtcb. Each is list is maintained in ascending sched_priority
+       * order.
+       */
+
+      for (;
+           (rtrtcb && pndtcb->sched_priority <= rtrtcb->sched_priority);
+           rtrtcb = rtrtcb->flink);
+
+      /* Add the pndtcb to the spot found in the list.  Check if the
+       * pndtcb goes at the ends of the g_readytorun list. This would be
+       * error condition since the idle test must always be at the end of
+       * the g_readytorun list!
+       */
+
+      if (!rtrtcb)
+        {
+          PANIC(OSERR_NOIDLETASK);
+        }
+      else
+        {
+          /* The pndtcb goes just before rtrtcb */
+
+          rtrprev = rtrtcb->blink;
+          if (!rtrprev)
+            {
+              /* Special case:  Inserting pndtcb at the head of the list */
+
+              pndtcb->flink = rtrtcb;
+              pndtcb->blink = NULL;
+              rtrtcb->blink = pndtcb;
+              g_readytorun.head = (dq_entry_t*)pndtcb;
+              rtrtcb->task_state = TSTATE_TASK_READYTORUN;
+              pndtcb->task_state = TSTATE_TASK_RUNNING;
+              ret = TRUE;
+            }
+          else
+            {
+              /* Insert in the middle of the list */
+
+              pndtcb->flink = rtrtcb;
+              pndtcb->blink = rtrprev;
+              rtrprev->flink = pndtcb;
+              rtrtcb->blink = pndtcb;
+              pndtcb->task_state = TSTATE_TASK_READYTORUN;
+            }
+        }
+
+      /* Set up for the next time through */
+
+      rtrtcb = pndtcb;
+    }
+
+  /* Mark the input list empty */
+
+  g_pendingtasks.head = NULL;
+  g_pendingtasks.tail = NULL;
+
+  return ret;
+}