171 lines
5.5 KiB
C
171 lines
5.5 KiB
C
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/************************************************************
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* sched_addprioritized.c
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*
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* Copyright (C) 2007 Gregory Nutt. All rights reserved.
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* Author: Gregory Nutt <spudmonkey@racsa.co.cr>
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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* 3. Neither the name Gregory Nutt nor the names of its contributors may be
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* used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
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* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
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* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
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* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
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* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
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* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
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* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
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* ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*
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************************************************************/
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/************************************************************
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* Included Files
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************************************************************/
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#include <sys/types.h>
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#include <queue.h>
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#include <assert.h>
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#include "os_internal.h"
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/************************************************************
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* Definitions
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************************************************************/
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/************************************************************
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* Private Type Declarations
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************************************************************/
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/************************************************************
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* Global Variables
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************************************************************/
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/************************************************************
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* Private Variables
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************************************************************/
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/************************************************************
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* Private Function Prototypes
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************************************************************/
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/************************************************************
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* Public Functions
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************************************************************/
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/************************************************************
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* Function: sched_addprioritized
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*
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* Description:
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* This function adds a TCB to a prioritized TCB list.
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*
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* Inputs:
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* tcb - Points to the TCB to add to the prioritized list
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* list - Points to the prioritized list to add tcb to
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*
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* Return Value:
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* TRUE if the head of the list has changed.
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*
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* Assumptions:
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* - The caller has established a critical section before
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* calling this function (calling sched_lock() first is NOT
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* a good idea -- use irqsave()).
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* - The caller has already removed the input tcb from
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* whatever list it was in.
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* - The caller handles the condition that occurs if the
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* the head of the task list is changed.
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* - The caller must set the task_state field of the TCB to
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* match the state associated with the list.
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************************************************************/
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boolean sched_addprioritized(_TCB *tcb, dq_queue_t *list)
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{
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_TCB *next;
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_TCB *prev;
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ubyte sched_priority = tcb->sched_priority;
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boolean ret = FALSE;
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/* Lets do a sanity check before we get started. */
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ASSERT(sched_priority >= SCHED_PRIORITY_MIN);
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/* Search the list to find the location to insert the new Tcb.
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* Each is list is maintained in ascending sched_priority order.
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*/
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for (next = (_TCB*)list->head;
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(next && sched_priority <= next->sched_priority);
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next = next->flink);
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/* Add the tcb to the spot found in the list. Check if the tcb
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* goes at the end of the list. NOTE: This could only happen if list
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* is the g_pendingtasks list!
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*/
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if (!next)
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{
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/* The tcb goes at the end of the list. */
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prev = (_TCB*)list->tail;
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if (!prev)
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{
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/* Special case: The list is empty */
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tcb->flink = NULL;
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tcb->blink = NULL;
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list->head = (dq_entry_t*)tcb;
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list->tail = (dq_entry_t*)tcb;
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ret = TRUE;
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}
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else
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{
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/* The tcb goes at the end of a non-empty list */
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tcb->flink = NULL;
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tcb->blink = prev;
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prev->flink = tcb;
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list->tail = (dq_entry_t*)tcb;
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}
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}
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else
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{
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/* The tcb goes just before next */
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prev = (_TCB*)next->blink;
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if (!prev)
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{
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/* Special case: Insert at the head of the list */
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tcb->flink = next;
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tcb->blink = NULL;
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next->blink = tcb;
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list->head = (dq_entry_t*)tcb;
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ret = TRUE;
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}
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else
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{
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/* Insert in the middle of the list */
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tcb->flink = next;
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tcb->blink = prev;
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prev->flink = tcb;
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next->blink = tcb;
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}
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}
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return ret;
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}
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