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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)
{
FAR _TCB *pndtcb;
FAR _TCB *pndnext;
FAR _TCB *rtrtcb;
FAR _TCB *rtrprev;
boolean ret = FALSE;
/* Initialize the inner search loop */
rtrtcb = (FAR _TCB*)g_readytorun.head;
/* Process every TCB in the g_pendingtasks list */
for (pndtcb = (FAR _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 = (FAR 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;
}
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