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/*
    FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.

    ***************************************************************************
    *                                                                         *
    * If you are:                                                             *
    *                                                                         *
    *    + New to FreeRTOS,                                                   *
    *    + Wanting to learn FreeRTOS or multitasking in general quickly       *
    *    + Looking for basic training,                                        *
    *    + Wanting to improve your FreeRTOS skills and productivity           *
    *                                                                         *
    * then take a look at the FreeRTOS books - available as PDF or paperback  *
    *                                                                         *
    *        "Using the FreeRTOS Real Time Kernel - a Practical Guide"        *
    *                  http://www.FreeRTOS.org/Documentation                  *
    *                                                                         *
    * A pdf reference manual is also available.  Both are usually delivered   *
    * to your inbox within 20 minutes to two hours when purchased between 8am *
    * and 8pm GMT (although please allow up to 24 hours in case of            *
    * exceptional circumstances).  Thank you for your support!                *
    *                                                                         *
    ***************************************************************************

    This file is part of the FreeRTOS distribution.

    FreeRTOS is free software; you can redistribute it and/or modify it under
    the terms of the GNU General Public License (version 2) as published by the
    Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
    ***NOTE*** The exception to the GPL is included to allow you to distribute
    a combined work that includes FreeRTOS without being obliged to provide the
    source code for proprietary components outside of the FreeRTOS kernel.
    FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
    ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
    FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
    more details. You should have received a copy of the GNU General Public
    License and the FreeRTOS license exception along with FreeRTOS; if not it
    can be viewed here: http://www.freertos.org/a00114.html and also obtained
    by writing to Richard Barry, contact details for whom are available on the
    FreeRTOS WEB site.

    1 tab == 4 spaces!

    http://www.FreeRTOS.org - Documentation, latest information, license and
    contact details.

    http://www.SafeRTOS.com - A version that is certified for use in safety
    critical systems.

    http://www.OpenRTOS.com - Commercial support, development, porting,
    licensing and training services.
*/
#include "msp430.h"
#include "FreeRTOSConfig.h"
#include "data_model.h"

        IMPORT vTaskIncrementTick
        IMPORT vTaskSwitchContext
        IMPORT vPortSetupTimerInterrupt
        IMPORT pxCurrentTCB
        IMPORT usCriticalNesting

        EXPORT vPortTickISR
        EXPORT vPortYield
        EXPORT xPortStartScheduler

portSAVE_CONTEXT macro

        /* Save the remaining registers. */
        pushm_x #12, r15
        mov.w   &usCriticalNesting, r14
        push_x r14
        mov_x   &pxCurrentTCB, r12
        mov_x   sp, 0( r12 )
        endm
/*-----------------------------------------------------------*/
                
portRESTORE_CONTEXT macro

        mov_x   &pxCurrentTCB, r12
        mov_x   @r12, sp
        pop_x   r15
        mov.w   r15, &usCriticalNesting
        popm_x  #12, r15
                
        /* The last thing on the stack will be the status register.
        Ensure the power down bits are clear ready for the next
        time this power down register is popped from the stack. */
        bic.w   #0xf0, 0( sp )
                
        pop.w   sr
        reta
        endm
/*-----------------------------------------------------------*/


/*
 * The RTOS tick ISR.
 *
 * If the cooperative scheduler is in use this simply increments the tick
 * count.
 *
 * If the preemptive scheduler is in use a context switch can also occur.
 */
        
        RSEG CODE
        EVEN
        
vPortTickISR:
        
        /* The sr is not saved in portSAVE_CONTEXT() because vPortYield() needs
        to save it manually before it gets modified (interrupts get disabled). */
        push.w sr
        portSAVE_CONTEXT
                                
        calla   #vTaskIncrementTick

        #if configUSE_PREEMPTION == 1
                calla   #vTaskSwitchContext
        #endif
                
        portRESTORE_CONTEXT
/*-----------------------------------------------------------*/

/*
 * Manual context switch called by the portYIELD() macro.
 */
        EVEN
        
vPortYield:

        /* The sr needs saving before it is modified. */
        push.w  sr
        
        /* Now the SR is stacked we can disable interrupts. */
        dint    
        nop
                                
        /* Save the context of the current task. */
        portSAVE_CONTEXT                        

        /* Select the next task to run. */
        calla   #vTaskSwitchContext             

        /* Restore the context of the new task. */
        portRESTORE_CONTEXT
/*-----------------------------------------------------------*/


/*
 * Start off the scheduler by initialising the RTOS tick timer, then restoring
 * the context of the first task.
 */
        EVEN
        
xPortStartScheduler:

        /* Setup the hardware to generate the tick.  Interrupts are disabled
        when this function is called. */
        calla   #vPortSetupTimerInterrupt

        /* Restore the context of the first task that is going to run. */
        portRESTORE_CONTEXT
/*-----------------------------------------------------------*/
                
        END