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/*
FreeRTOS.org V5.1.2 - Copyright (C) 2003-2009 Richard Barry.
This file is part of the FreeRTOS.org distribution.
FreeRTOS.org is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
FreeRTOS.org 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
along with FreeRTOS.org; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
***************************************************************************
* *
* Get the FreeRTOS eBook! See http://www.FreeRTOS.org/Documentation *
* *
* This is a concise, step by step, 'hands on' guide that describes both *
* general multitasking concepts and FreeRTOS specifics. It presents and *
* explains numerous examples that are written using the FreeRTOS API. *
* Full source code for all the examples is provided in an accompanying *
* .zip file. *
* *
***************************************************************************
***************************************************************************
Please ensure to read the configuration and relevant port sections of the
online documentation.
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.
*/
/*-----------------------------------------------------------
* 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 portTIMER_COMPARE ( unsigned portSHORT ) ( ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) / ( unsigned portLONG ) 4 )
/* From the RDC data sheet. */
#define portENABLE_TIMER_AND_INTERRUPT ( unsigned portSHORT ) 0xe001
/* 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 );
/* The timer initialisation functions leave interrupts enabled,
which is not what we want. This ISR is installed temporarily in case
the timer fires before we get a change to disable interrupts again. */
static void __interrupt __far prvDummyISR( void );
/*-----------------------------------------------------------*/
/* See header file for description. */
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
portSTACK_TYPE DS_Reg = 0;
/* 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_SEG( pvParameters );
pxTopOfStack--;
*pxTopOfStack = FP_OFF( pvParameters );
pxTopOfStack--;
*pxTopOfStack = FP_SEG( pxCode );
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 = ( portSTACK_TYPE ) 0xAAAA; /* AX */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0xBBBB; /* BX */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0xCCCC; /* CX */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0xDDDD; /* DX */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0xEEEE; /* ES */
pxTopOfStack--;
/* We need the true data segment. */
__asm{ MOV DS_Reg, DS };
*pxTopOfStack = DS_Reg; /* DS */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0x0123; /* SI */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0xDDDD; /* DI */
pxTopOfStack--;
*pxTopOfStack = ( portSTACK_TYPE ) 0xBBBB; /* BP */
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
portBASE_TYPE 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;
}
/*-----------------------------------------------------------*/
static void __interrupt __far prvDummyISR( void )
{
/* The timer initialisation functions leave interrupts enabled,
which is not what we want. This ISR is installed temporarily in case
the timer fires before we get a change to disable interrupts again. */
outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
}
/*-----------------------------------------------------------*/
/* 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. */
vTaskIncrementTick();
/* Switch in the context of the next task to be run. */
portSWITCH_CONTEXT();
/* 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. */
vTaskIncrementTick();
/* 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. */
portSWITCH_CONTEXT();
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* Not implemented. */
}
/*-----------------------------------------------------------*/
static void prvSetupTimerInterrupt( void )
{
const unsigned portSHORT usTimerACompare = portTIMER_COMPARE, usTimerAMode = portENABLE_TIMER_AND_INTERRUPT;
const unsigned portSHORT usT2_IRQ = 0x13;
/* Configure the timer, the dummy handler is used here as the init
function leaves interrupts enabled. */
t2_init( usTimerAMode, usTimerACompare, prvDummyISR );
/* Disable interrupts again before installing the real handlers. */
portDISABLE_INTERRUPTS();
#if( configUSE_PREEMPTION == 1 )
/* Tick service routine used by the scheduler when preemptive scheduling is
being used. */
setvect( usT2_IRQ, prvPreemptiveTick );
#else
/* Tick service routine used by the scheduler when cooperative scheduling is
being used. */
setvect( usT2_IRQ, prvNonPreemptiveTick );
#endif
}
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