/*
 * FreeRTOS Kernel <DEVELOPMENT BRANCH>
 * Copyright (C) 2021 Amazon.com, Inc. or its affiliates.  All Rights Reserved.
 *
 * SPDX-License-Identifier: MIT
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy of
 * this software and associated documentation files (the "Software"), to deal in
 * the Software without restriction, including without limitation the rights to
 * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
 * the Software, and to permit persons to whom the Software is furnished to do so,
 * subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in all
 * copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS
 * FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR
 * COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
 * IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 *
 * https://www.FreeRTOS.org
 * https://github.com/FreeRTOS
 *
 */
#include "FreeRTOSConfig.h"
#include "portasm.h"

    IMPORT xTaskIncrementTick
    IMPORT vTaskSwitchContext
    IMPORT vPortSetupTimerInterrupt

    EXPORT vTickISR
    EXPORT vPortYield
    EXPORT xPortStartScheduler

    RSEG CODE

/*
 * 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.
 */
vTickISR:
    portSAVE_CONTEXT

    call    #xTaskIncrementTick
    cmp.w   #0x0, R12
    jeq     SkipContextSwitch
    call    #vTaskSwitchContext
SkipContextSwitch:

    portRESTORE_CONTEXT
/*-----------------------------------------------------------*/


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

    /* Mimic an interrupt by pushing the SR. */
    push    SR

    /* Now the SR is stacked we can disable interrupts. */
    dint

    /* Save the context of the current task. */
    portSAVE_CONTEXT

    /* Switch to the highest priority task that is ready to run. */
    call    #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.
 */
xPortStartScheduler:

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

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


    /* Install vTickISR as the timer A0 interrupt. */
    ASEG
    ORG 0xFFE0 + TIMERA0_VECTOR

    _vTickISR_: DC16 vTickISR


    END
