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/*
* FreeRTOS Kernel V10.2.1
* Copyright (C) 2019 Amazon.com, Inc. or its affiliates. All Rights Reserved.
*
* 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.
*
* http://www.FreeRTOS.org
* http://aws.amazon.com/freertos
*
* 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 portTIMER_COMPARE ( uint16_t ) ( ( configCPU_CLOCK_HZ / configTICK_RATE_HZ ) / ( uint32_t ) 4 )
/* From the RDC data sheet. */
#define portENABLE_TIMER_AND_INTERRUPT ( uint16_t ) 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. */
StackType_t *pxPortInitialiseStack( StackType_t *pxTopOfStack, TaskFunction_t pxCode, void *pvParameters )
{
StackType_t 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 = ( 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--;
/* We need the true data segment. */
__asm{ MOV DS_Reg, DS };
*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;
}
/*-----------------------------------------------------------*/
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. */
if( xTaskIncrementTick() != pdFALSE )
{
/* 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. */
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. */
portSWITCH_CONTEXT();
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* Not implemented. */
}
/*-----------------------------------------------------------*/
static void prvSetupTimerInterrupt( void )
{
const uint16_t usTimerACompare = portTIMER_COMPARE, usTimerAMode = portENABLE_TIMER_AND_INTERRUPT;
const uint16_t 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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