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/*
FreeRTOS V8.1.1 - Copyright (C) 2014 Real Time Engineers Ltd.
All rights reserved
VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
***************************************************************************
* *
* FreeRTOS provides completely free yet professionally developed, *
* robust, strictly quality controlled, supported, and cross *
* platform software that has become a de facto standard. *
* *
* Help yourself get started quickly and support the FreeRTOS *
* project by purchasing a FreeRTOS tutorial book, reference *
* manual, or both from: http://www.FreeRTOS.org/Documentation *
* *
* Thank you! *
* *
***************************************************************************
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 modification 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. Full license text is available from the following
link: http://www.freertos.org/a00114.html
1 tab == 4 spaces!
***************************************************************************
* *
* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
* *
* http://www.FreeRTOS.org/FAQHelp.html *
* *
***************************************************************************
http://www.FreeRTOS.org - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details.
http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, a DOS
compatible FAT file system, and our tiny thread aware UDP/IP stack.
http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
licenses offer ticketed support, indemnification and middleware.
http://www.SafeRTOS.com - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
1 tab == 4 spaces!
*/
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the Tern EE 186
* port.
*----------------------------------------------------------*/
/* Library includes. */
#include <embedded.h>
#include <ae.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
#include "portasm.h"
/* The timer increments every four clocks, hence the divide by 4. */
#define portPRESCALE_VALUE ( 16 )
#define portTIMER_COMPARE ( configCPU_CLOCK_HZ / ( configTICK_RATE_HZ * 4UL ) )
/* From the RDC data sheet. */
#define portENABLE_TIMER_AND_INTERRUPT ( uint16_t ) 0xe00b
#define portENABLE_TIMER ( uint16_t ) 0xC001
/* Interrupt control. */
#define portEIO_REGISTER 0xff22
#define portCLEAR_INTERRUPT 0x0008
/* Setup the hardware to generate the required tick frequency. */
static void prvSetupTimerInterrupt( void );
/* The ISR used depends on whether the preemptive or cooperative scheduler
is being used. */
#if( configUSE_PREEMPTION == 1 )
/* Tick service routine used by the scheduler when preemptive scheduling is
being used. */
static void __interrupt __far prvPreemptiveTick( void );
#else
/* Tick service routine used by the scheduler when cooperative scheduling is
being used. */
static void __interrupt __far prvNonPreemptiveTick( void );
#endif
/* Trap routine used by taskYIELD() to manually cause a context switch. */
static void __interrupt __far prvYieldProcessor( void );
/*-----------------------------------------------------------*/
/* See header file for description. */
StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
{
StackType_t DS_Reg = 0;
/* We need the true data segment. */
__asm{ MOV DS_Reg, DS };
/* Place a few bytes of known values on the bottom of the stack.
This is just useful for debugging. */
*pxTopOfStack = 0x1111;
pxTopOfStack--;
*pxTopOfStack = 0x2222;
pxTopOfStack--;
*pxTopOfStack = 0x3333;
pxTopOfStack--;
/* We are going to start the scheduler using a return from interrupt
instruction to load the program counter, so first there would be the
function call with parameters preamble. */
*pxTopOfStack = FP_OFF( pvParameters );
pxTopOfStack--;
*pxTopOfStack = FP_OFF( pxCode );
pxTopOfStack--;
/* Next the status register and interrupt return address. */
*pxTopOfStack = portINITIAL_SW;
pxTopOfStack--;
*pxTopOfStack = FP_SEG( pxCode );
pxTopOfStack--;
*pxTopOfStack = FP_OFF( pxCode );
pxTopOfStack--;
/* The remaining registers would be pushed on the stack by our context
switch function. These are loaded with values simply to make debugging
easier. */
*pxTopOfStack = ( StackType_t ) 0xAAAA; /* AX */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xBBBB; /* BX */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xCCCC; /* CX */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xDDDD; /* DX */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xEEEE; /* ES */
pxTopOfStack--;
*pxTopOfStack = DS_Reg; /* DS */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0x0123; /* SI */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xDDDD; /* DI */
pxTopOfStack--;
*pxTopOfStack = ( StackType_t ) 0xBBBB; /* BP */
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
BaseType_t xPortStartScheduler( void )
{
/* This is called with interrupts already disabled. */
/* Put our manual switch (yield) function on a known
vector. */
setvect( portSWITCH_INT_NUMBER, prvYieldProcessor );
/* Setup the tick interrupt. */
prvSetupTimerInterrupt();
/* Kick off the scheduler by setting up the context of the first task. */
portFIRST_CONTEXT();
/* Should not get here! */
return pdFALSE;
}
/*-----------------------------------------------------------*/
/* The ISR used depends on whether the preemptive or cooperative scheduler
is being used. */
#if( configUSE_PREEMPTION == 1 )
static void __interrupt __far prvPreemptiveTick( void )
{
/* Get the scheduler to update the task states following the tick. */
if( xTaskIncrementTick() != pdFALSE )
{
/* Switch in the context of the next task to be run. */
portEND_SWITCHING_ISR();
}
/* Reset interrupt. */
outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
}
#else
static void __interrupt __far prvNonPreemptiveTick( void )
{
/* Same as preemptive tick, but the cooperative scheduler is being used
so we don't have to switch in the context of the next task. */
xTaskIncrementTick();
/* Reset interrupt. */
outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
}
#endif
/*-----------------------------------------------------------*/
static void __interrupt __far prvYieldProcessor( void )
{
/* Switch in the context of the next task to be run. */
portEND_SWITCHING_ISR();
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* Not implemented. */
}
/*-----------------------------------------------------------*/
static void prvSetupTimerInterrupt( void )
{
const uint32_t ulCompareValue = portTIMER_COMPARE;
uint16_t usTimerCompare;
usTimerCompare = ( uint16_t ) ( ulCompareValue >> 4 );
t2_init( portENABLE_TIMER, portPRESCALE_VALUE, NULL );
#if( configUSE_PREEMPTION == 1 )
/* Tick service routine used by the scheduler when preemptive scheduling is
being used. */
t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvPreemptiveTick );
#else
/* Tick service routine used by the scheduler when cooperative scheduling is
being used. */
t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvNonPreemptiveTick );
#endif
}
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