mirror of
https://github.com/FreeRTOS/FreeRTOS-Kernel.git
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244 lines
8.9 KiB
C
244 lines
8.9 KiB
C
/*
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FreeRTOS V6.1.1 - Copyright (C) 2011 Real Time Engineers Ltd.
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***************************************************************************
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* *
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* If you are: *
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* *
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* + New to FreeRTOS, *
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* + Wanting to learn FreeRTOS or multitasking in general quickly *
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* + Looking for basic training, *
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* + Wanting to improve your FreeRTOS skills and productivity *
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* *
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* then take a look at the FreeRTOS books - available as PDF or paperback *
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* *
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* "Using the FreeRTOS Real Time Kernel - a Practical Guide" *
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* http://www.FreeRTOS.org/Documentation *
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* *
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* A pdf reference manual is also available. Both are usually delivered *
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* to your inbox within 20 minutes to two hours when purchased between 8am *
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* and 8pm GMT (although please allow up to 24 hours in case of *
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* exceptional circumstances). Thank you for your support! *
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* *
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***************************************************************************
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This file is part of the FreeRTOS distribution.
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FreeRTOS is free software; you can redistribute it and/or modify it under
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the terms of the GNU General Public License (version 2) as published by the
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Free Software Foundation AND MODIFIED BY the FreeRTOS exception.
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***NOTE*** The exception to the GPL is included to allow you to distribute
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a combined work that includes FreeRTOS without being obliged to provide the
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source code for proprietary components outside of the FreeRTOS kernel.
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FreeRTOS is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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more details. You should have received a copy of the GNU General Public
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License and the FreeRTOS license exception along with FreeRTOS; if not it
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can be viewed here: http://www.freertos.org/a00114.html and also obtained
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by writing to Richard Barry, contact details for whom are available on the
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FreeRTOS WEB site.
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1 tab == 4 spaces!
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http://www.FreeRTOS.org - Documentation, latest information, license and
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contact details.
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http://www.SafeRTOS.com - A version that is certified for use in safety
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critical systems.
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http://www.OpenRTOS.com - Commercial support, development, porting,
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licensing and training services.
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*/
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/*-----------------------------------------------------------
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* Implementation of functions defined in portable.h for the Tern EE 186
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* port.
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*----------------------------------------------------------*/
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/* Library includes. */
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#include <embedded.h>
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#include <ae.h>
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/* Scheduler includes. */
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#include "FreeRTOS.h"
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#include "task.h"
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#include "portasm.h"
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/* The timer increments every four clocks, hence the divide by 4. */
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#define portPRESCALE_VALUE ( 16 )
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#define portTIMER_COMPARE ( configCPU_CLOCK_HZ / ( configTICK_RATE_HZ * 4UL ) )
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/* From the RDC data sheet. */
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#define portENABLE_TIMER_AND_INTERRUPT ( unsigned short ) 0xe00b
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#define portENABLE_TIMER ( unsigned short ) 0xC001
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/* Interrupt control. */
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#define portEIO_REGISTER 0xff22
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#define portCLEAR_INTERRUPT 0x0008
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/* Setup the hardware to generate the required tick frequency. */
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static void prvSetupTimerInterrupt( void );
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/* The ISR used depends on whether the preemptive or cooperative scheduler
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is being used. */
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#if( configUSE_PREEMPTION == 1 )
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/* Tick service routine used by the scheduler when preemptive scheduling is
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being used. */
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static void __interrupt __far prvPreemptiveTick( void );
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#else
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/* Tick service routine used by the scheduler when cooperative scheduling is
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being used. */
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static void __interrupt __far prvNonPreemptiveTick( void );
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#endif
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/* Trap routine used by taskYIELD() to manually cause a context switch. */
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static void __interrupt __far prvYieldProcessor( void );
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/*-----------------------------------------------------------*/
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/* See header file for description. */
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portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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{
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portSTACK_TYPE DS_Reg = 0;
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/* We need the true data segment. */
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__asm{ MOV DS_Reg, DS };
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/* Place a few bytes of known values on the bottom of the stack.
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This is just useful for debugging. */
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*pxTopOfStack = 0x1111;
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pxTopOfStack--;
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*pxTopOfStack = 0x2222;
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pxTopOfStack--;
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*pxTopOfStack = 0x3333;
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pxTopOfStack--;
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/* We are going to start the scheduler using a return from interrupt
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instruction to load the program counter, so first there would be the
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function call with parameters preamble. */
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*pxTopOfStack = FP_OFF( pvParameters );
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pxTopOfStack--;
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*pxTopOfStack = FP_OFF( pxCode );
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pxTopOfStack--;
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/* Next the status register and interrupt return address. */
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*pxTopOfStack = portINITIAL_SW;
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pxTopOfStack--;
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*pxTopOfStack = FP_SEG( pxCode );
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pxTopOfStack--;
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*pxTopOfStack = FP_OFF( pxCode );
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pxTopOfStack--;
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/* The remaining registers would be pushed on the stack by our context
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switch function. These are loaded with values simply to make debugging
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easier. */
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*pxTopOfStack = ( portSTACK_TYPE ) 0xAAAA; /* AX */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0xBBBB; /* BX */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0xCCCC; /* CX */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0xDDDD; /* DX */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0xEEEE; /* ES */
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pxTopOfStack--;
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*pxTopOfStack = DS_Reg; /* DS */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x0123; /* SI */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0xDDDD; /* DI */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0xBBBB; /* BP */
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return pxTopOfStack;
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}
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/*-----------------------------------------------------------*/
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portBASE_TYPE xPortStartScheduler( void )
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{
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/* This is called with interrupts already disabled. */
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/* Put our manual switch (yield) function on a known
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vector. */
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setvect( portSWITCH_INT_NUMBER, prvYieldProcessor );
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/* Setup the tick interrupt. */
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prvSetupTimerInterrupt();
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/* Kick off the scheduler by setting up the context of the first task. */
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portFIRST_CONTEXT();
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/* Should not get here! */
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return pdFALSE;
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}
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/*-----------------------------------------------------------*/
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/* The ISR used depends on whether the preemptive or cooperative scheduler
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is being used. */
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#if( configUSE_PREEMPTION == 1 )
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static void __interrupt __far prvPreemptiveTick( void )
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{
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/* Get the scheduler to update the task states following the tick. */
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vTaskIncrementTick();
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/* Switch in the context of the next task to be run. */
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portEND_SWITCHING_ISR();
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/* Reset interrupt. */
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outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
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}
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#else
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static void __interrupt __far prvNonPreemptiveTick( void )
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{
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/* Same as preemptive tick, but the cooperative scheduler is being used
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so we don't have to switch in the context of the next task. */
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vTaskIncrementTick();
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/* Reset interrupt. */
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outport( portEIO_REGISTER, portCLEAR_INTERRUPT );
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}
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#endif
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/*-----------------------------------------------------------*/
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static void __interrupt __far prvYieldProcessor( void )
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{
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/* Switch in the context of the next task to be run. */
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portEND_SWITCHING_ISR();
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}
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/*-----------------------------------------------------------*/
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void vPortEndScheduler( void )
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{
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/* Not implemented. */
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}
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/*-----------------------------------------------------------*/
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static void prvSetupTimerInterrupt( void )
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{
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const unsigned long ulCompareValue = portTIMER_COMPARE;
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unsigned short usTimerCompare;
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usTimerCompare = ( unsigned short ) ( ulCompareValue >> 4 );
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t2_init( portENABLE_TIMER, portPRESCALE_VALUE, NULL );
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#if( configUSE_PREEMPTION == 1 )
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/* Tick service routine used by the scheduler when preemptive scheduling is
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being used. */
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t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvPreemptiveTick );
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#else
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/* Tick service routine used by the scheduler when cooperative scheduling is
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being used. */
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t1_init( portENABLE_TIMER_AND_INTERRUPT, usTimerCompare, usTimerCompare, prvNonPreemptiveTick );
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#endif
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}
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