/****************************************************************************
* arch/mips/src/mips32/up_blocktask.c
*
* Copyright (C) 2011, 2013-2014 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 <syscall.h>
#include <debug.h>
#include <nuttx/arch.h>
#include "sched/sched.h"
#include "group/group.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(struct tcb_s *tcb, tstate_t task_state)
{
struct tcb_s *rtcb = (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));
/* 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 (current_regs)
{
/* Yes, then we have to do things differently.
* Just copy the current_regs into the OLD rtcb.
*/
up_savestate(rtcb->xcp.regs);
/* Restore the exception context of the rtcb at the (new) head
* of the g_readytorun task list.
*/
rtcb = (struct tcb_s*)g_readytorun.head;
/* Then switch contexts. Any necessary address environment
* changes will be made when the interrupt returns.
*/
up_restorestate(rtcb->xcp.regs);
}
/* No, then we will need to perform the user context switch */
else
{
/* Get the context of the task at the head of the ready to
* run list.
*/
struct tcb_s *nexttcb = (struct tcb_s*)g_readytorun.head;
#ifdef CONFIG_ARCH_ADDRENV
/* Make sure that the address environment for the previously
* running task is closed down gracefully (data caches dump,
* MMU flushed) and set up the address environment for the new
* thread at the head of the ready-to-run list.
*/
(void)group_addrenv(nexttcb);
#endif
/* Then switch contexts */
up_switchcontext(rtcb->xcp.regs, nexttcb->xcp.regs);
/* up_switchcontext forces a context switch to the task at the
* head of the ready-to-run list. It does not 'return' in the
* normal sense. When it does return, it is because the blocked
* task is again ready to run and has execution priority.
*/
}
}
}
