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/*
* 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
*
*/
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the MSP430 port.
*----------------------------------------------------------*/
/* Constants required for hardware setup. The tick ISR runs off the ACLK,
* not the MCLK. */
#define portACLK_FREQUENCY_HZ ( ( TickType_t ) 32768 )
#define portINITIAL_CRITICAL_NESTING ( ( uint16_t ) 10 )
#define portFLAGS_INT_ENABLED ( ( StackType_t ) 0x08 )
/* We require the address of the pxCurrentTCB variable, but don't want to know
* any details of its type. */
typedef void TCB_t;
extern volatile TCB_t * volatile pxCurrentTCB;
/* Each task maintains a count of the critical section nesting depth. Each
* time a critical section is entered the count is incremented. Each time a
* critical section is exited the count is decremented - with interrupts only
* being re-enabled if the count is zero.
*
* usCriticalNesting will get set to zero when the scheduler starts, but must
* not be initialised to zero as this will cause problems during the startup
* sequence. */
volatile uint16_t usCriticalNesting = portINITIAL_CRITICAL_NESTING;
/*-----------------------------------------------------------*/
/*
* Sets up the periodic ISR used for the RTOS tick. This uses timer 0, but
* could have alternatively used the watchdog timer or timer 1.
*/
void vPortSetupTimerInterrupt( void );
/*-----------------------------------------------------------*/
/*
* Initialise the stack of a task to look exactly as if a call to
* portSAVE_CONTEXT had been called.
*
* See the header file portable.h.
*/
StackType_t * pxPortInitialiseStack( StackType_t * pxTopOfStack,
TaskFunction_t pxCode,
void * pvParameters )
{
/*
* Place a few bytes of known values on the bottom of the stack.
* This is just useful for debugging and can be included if required.
*
* pxTopOfStack = ( StackType_t ) 0x1111;
* pxTopOfStack--;
* pxTopOfStack = ( StackType_t ) 0x2222;
* pxTopOfStack--;
* pxTopOfStack = ( StackType_t ) 0x3333;
* pxTopOfStack--;
*/
/* The msp430 automatically pushes the PC then SR onto the stack before
* executing an ISR. We want the stack to look just as if this has happened
* so place a pointer to the start of the task on the stack first - followed
* by the flags we want the task to use when it starts up. */
*pxTopOfStack = ( StackType_t ) pxCode;
pxTopOfStack--;
*pxTopOfStack = portFLAGS_INT_ENABLED;
pxTopOfStack--;
/* Next the general purpose registers. */
*pxTopOfStack = ( StackType_t ) 0x4444;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x5555;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x6666;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x7777;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x8888;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x9999;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xaaaa;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xbbbb;
pxTopOfStack--;
/* When the task starts is will expect to find the function parameter in
* R15. */
*pxTopOfStack = ( StackType_t ) pvParameters;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xdddd;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xeeee;
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xffff;
pxTopOfStack--;
/* A variable is used to keep track of the critical section nesting.
* This variable has to be stored as part of the task context and is
* initially set to zero. */
*pxTopOfStack = ( StackType_t ) portNO_CRITICAL_SECTION_NESTING;
/* Return a pointer to the top of the stack we have generated so this can
* be stored in the task control block for the task. */
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* It is unlikely that the MSP430 port will get stopped. If required simply
* disable the tick interrupt here. */
}
/*-----------------------------------------------------------*/
/*
* Hardware initialisation to generate the RTOS tick. This uses timer 0
* but could alternatively use the watchdog timer or timer 1.
*/
void vPortSetupTimerInterrupt( void )
{
/* Ensure the timer is stopped. */
TACTL = 0;
/* Run the timer of the ACLK. */
TACTL = TASSEL_1;
/* Clear everything to start with. */
TACTL |= TACLR;
/* Set the compare match value according to the tick rate we want. */
TACCR0 = portACLK_FREQUENCY_HZ / configTICK_RATE_HZ;
/* Enable the interrupts. */
TACCTL0 = CCIE;
/* Start up clean. */
TACTL |= TACLR;
/* Up mode. */
TACTL |= MC_1;
}
/*-----------------------------------------------------------*/