/****************************************************************************
* common/up_blocktask.c
*
* Copyright (C) 2008-2009, 2013 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 <sched.h>
#include <debug.h>
#include <nuttx/arch.h>
#include "sched/sched.h"
#include "up_internal.h"
/****************************************************************************
* Pre-processor Definitions
****************************************************************************/
/****************************************************************************
* Private Data
****************************************************************************/
/****************************************************************************
* Private Functions
****************************************************************************/
/****************************************************************************
* Public Functions
****************************************************************************/
/****************************************************************************
* Name: up_block_task
*
* Description:
* The currently executing task at the head of
* the ready to run list must be stopped. Save its context
* and move it to the inactive list specified by task_state.
*
* Inputs:
* tcb: Refers to a task in the ready-to-run list (normally
* the task at the head of the list). It most be
* stopped, its context saved and moved into one of the
* waiting task lists. It it was the task at the head
* of the ready-to-run list, then a context to the new
* ready to run task must be performed.
* task_state: Specifies which waiting task list should be
* hold the blocked task TCB.
*
****************************************************************************/
void up_block_task(FAR struct tcb_s *tcb, tstate_t task_state)
{
FAR struct tcb_s *rtcb = (FAR struct tcb_s*)g_readytorun.head;
bool switch_needed;
/* Verify that the context switch can be performed */
ASSERT((tcb->task_state >= FIRST_READY_TO_RUN_STATE) &&
(tcb->task_state <= LAST_READY_TO_RUN_STATE));
/* dbg("Blocking TCB=%p\n", tcb); */
/* Remove the tcb task from the ready-to-run list. If we
* are blocking the task at the head of the task list (the
* most likely case), then a context switch to the next
* ready-to-run task is needed. In this case, it should
* also be true that rtcb == tcb.
*/
switch_needed = sched_removereadytorun(tcb);
/* Add the task to the specified blocked task list */
sched_addblocked(tcb, (tstate_t)task_state);
/* If there are any pending tasks, then add them to the g_readytorun
* task list now
*/
if (g_pendingtasks.head)
{
switch_needed |= sched_mergepending();
}
/* Now, perform the context switch if one is needed */
if (switch_needed)
{
/* Are we in an interrupt handler? */
if (IN_INTERRUPT)
{
/* Yes, then we have to do things differently.
* Just copy the current registers into the OLD rtcb.
*/
SAVE_IRQCONTEXT(rtcb);
/* Restore the exception context of the rtcb at the (new) head
* of the g_readytorun task list.
*/
rtcb = (FAR struct tcb_s*)g_readytorun.head;
/* dbg("New Active Task TCB=%p\n", rtcb); */
/* Then setup so that the context will be performed on exit
* from the interrupt.
*/
SET_IRQCONTEXT(rtcb);
}
/* Copy the user C context into the TCB at the (old) head of the
* g_readytorun Task list. if SAVE_USERCONTEXT returns a non-zero
* value, then this is really the previously running task restarting!
*/
else if (!SAVE_USERCONTEXT(rtcb))
{
/* Restore the exception context of the rtcb at the (new) head
* of the g_readytorun task list.
*/
rtcb = (FAR struct tcb_s*)g_readytorun.head;
/* dbg("New Active Task TCB=%p\n", rtcb); */
/* Then switch contexts */
RESTORE_USERCONTEXT(rtcb);
}
}
}
