/************************************************************
* up_unblocktask.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 <nuttx/config.h>
#include <sys/types.h>
#include <sched.h>
#include <debug.h>
#include <nuttx/arch.h>
#include "os_internal.h"
#include "up_internal.h"
/************************************************************
* Private Definitions
************************************************************/
/************************************************************
* Private Data
************************************************************/
/************************************************************
* Private Funtions
************************************************************/
/************************************************************
* Public Funtions
************************************************************/
/************************************************************
* Name: up_unblock_task
*
* Description:
* A task is currently in an inactive task list
* but has been prepped to execute. Move the TCB to the
* ready-to-run list, restore its context, and start execution.
*
* Inputs:
* tcb: Refers to the tcb to be unblocked. This tcb is
* in one of the waiting tasks lists. It must be moved to
* the ready-to-run list and, if it is the highest priority
* ready to run taks, executed.
*
************************************************************/
void up_unblock_task(_TCB *tcb)
{
/* Verify that the context switch can be performed */
if ((tcb->task_state < FIRST_BLOCKED_STATE) ||
(tcb->task_state > LAST_BLOCKED_STATE))
{
PANIC(OSERR_BADUNBLOCKSTATE);
}
else
{
_TCB *rtcb = (_TCB*)g_readytorun.head;
dbg("Unblocking TCB=%p\n", tcb);
/* Remove the task from the blocked task list */
sched_removeblocked(tcb);
/* Reset its timeslice. This is only meaningful for round
* robin tasks but it doesn't here to do it for everything
*/
#if CONFIG_RR_INTERVAL > 0
tcb->timeslice = CONFIG_RR_INTERVAL;
#endif
/* Add the task in the correct location in the prioritized
* g_readytorun task list
*/
if (sched_addreadytorun(tcb))
{
/* The currently active task has changed! We need to do
* a context switch to the new task.
*
* Are we in an interrupt handler?
*/
if (current_regs)
{
/* Yes, then we have to do things differently.
* Just copy the current_regs into the OLD rtcb.
*/
up_copystate(rtcb->xcp.regs, current_regs);
/* Restore the exception context of the rtcb at the (new) head
* of the g_readytorun task list.
*/
rtcb = (_TCB*)g_readytorun.head;
dbg("New Active Task TCB=%p\n", rtcb);
/* Then switch contexts */
up_copystate(current_regs, rtcb->xcp.regs);
}
/* We are not in an interrupt andler. Copy the user C context
* into the TCB of the task that was previously active. if
* up_saveusercontext returns a non-zero value, then this is really the
* previously running task restarting!
*/
else if (!up_saveusercontext(rtcb->xcp.regs))
{
/* Restore the exception context of the new task that is ready to
* run (probably tcb). This is the new rtcb at the head of the
* g_readytorun task list.
*/
rtcb = (_TCB*)g_readytorun.head;
dbg("New Active Task TCB=%p\n", rtcb);
/* Then switch contexts */
up_fullcontextrestore(rtcb->xcp.regs);
}
}
}
}
