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349 lines
12 KiB
C
349 lines
12 KiB
C
/*
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FreeRTOS.org V4.6.0 - Copyright (C) 2003-2007 Richard Barry.
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This file is part of the FreeRTOS.org distribution.
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FreeRTOS.org is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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FreeRTOS.org is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with FreeRTOS.org; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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A special exception to the GPL can be applied should you wish to distribute
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a combined work that includes FreeRTOS.org, without being obliged to provide
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the source code for any proprietary components. See the licensing section
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of http://www.FreeRTOS.org for full details of how and when the exception
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can be applied.
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***************************************************************************
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See http://www.FreeRTOS.org for documentation, latest information, license
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and contact details. Please ensure to read the configuration and relevant
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port sections of the online documentation.
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Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along
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with commercial development and support options.
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***************************************************************************
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*/
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#include <stdlib.h>
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#include "FreeRTOS.h"
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#include "task.h"
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/*-----------------------------------------------------------
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* Implementation of functions defined in portable.h for the AVR/IAR port.
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*----------------------------------------------------------*/
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/* Start tasks with interrupts enables. */
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#define portFLAGS_INT_ENABLED ( ( portSTACK_TYPE ) 0x80 )
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/* Hardware constants for timer 1. */
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#define portCLEAR_COUNTER_ON_MATCH ( ( unsigned portCHAR ) 0x08 )
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#define portPRESCALE_64 ( ( unsigned portCHAR ) 0x03 )
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#define portCLOCK_PRESCALER ( ( unsigned portLONG ) 64 )
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#define portCOMPARE_MATCH_A_INTERRUPT_ENABLE ( ( unsigned portCHAR ) 0x10 )
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/* The number of bytes used on the hardware stack by the task start address. */
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#define portBYTES_USED_BY_RETURN_ADDRESS ( 2 )
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/*-----------------------------------------------------------*/
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/* Stores the critical section nesting. This must not be initialised to 0.
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It will be initialised when a task starts. */
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#define portNO_CRITICAL_NESTING ( ( unsigned portBASE_TYPE ) 0 )
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unsigned portBASE_TYPE uxCriticalNesting = 0x50;
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/*
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* Perform hardware setup to enable ticks from timer 1, compare match A.
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*/
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static void prvSetupTimerInterrupt( void );
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/*
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* The IAR compiler does not have full support for inline assembler, so
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* these are defined in the portmacro assembler file.
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*/
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extern void vPortYieldFromTick( void );
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extern void vPortStart( void );
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/*-----------------------------------------------------------*/
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/*
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* See header file for description.
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*/
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portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
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{
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unsigned portSHORT usAddress;
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portSTACK_TYPE *pxTopOfHardwareStack;
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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 = 0x11;
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pxTopOfStack--;
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*pxTopOfStack = 0x22;
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pxTopOfStack--;
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*pxTopOfStack = 0x33;
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pxTopOfStack--;
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/* Remember where the top of the hardware stack is - this is required
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below. */
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pxTopOfHardwareStack = pxTopOfStack;
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/* Simulate how the stack would look after a call to vPortYield(). */
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/*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */
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/* The IAR compiler requires two stacks per task. First there is the
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hardware call stack which uses the AVR stack pointer. Second there is the
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software stack (local variables, parameter passing, etc.) which uses the
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AVR Y register.
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This function places both stacks within the memory block passed in as the
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first parameter. The hardware stack is placed at the bottom of the memory
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block. A gap is then left for the hardware stack to grow. Next the software
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stack is placed. The amount of space between the software and hardware
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stacks is defined by configCALL_STACK_SIZE.
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The first part of the stack is the hardware stack. Place the start
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address of the task on the hardware stack. */
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usAddress = ( unsigned portSHORT ) pxCode;
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff );
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pxTopOfStack--;
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usAddress >>= 8;
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff );
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pxTopOfStack--;
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/* Leave enough space for the hardware stack before starting the software
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stack. The '- 2' is because we have already used two spaces for the
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address of the start of the task. */
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pxTopOfStack -= ( configCALL_STACK_SIZE - 2 );
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/* Next simulate the stack as if after a call to portSAVE_CONTEXT().
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portSAVE_CONTEXT places the flags on the stack immediately after r0
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to ensure the interrupts get disabled as soon as possible, and so ensuring
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the stack use is minimal should a context switch interrupt occur. */
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*pxTopOfStack = ( portSTACK_TYPE ) 0x00; /* R0 */
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pxTopOfStack--;
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*pxTopOfStack = portFLAGS_INT_ENABLED;
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pxTopOfStack--;
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/* Next place the address of the hardware stack. This is required so
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the AVR stack pointer can be restored to point to the hardware stack. */
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pxTopOfHardwareStack -= portBYTES_USED_BY_RETURN_ADDRESS;
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usAddress = ( unsigned portSHORT ) pxTopOfHardwareStack;
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/* SPL */
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff );
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pxTopOfStack--;
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/* SPH */
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usAddress >>= 8;
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff );
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pxTopOfStack--;
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/* Now the remaining registers. */
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*pxTopOfStack = ( portSTACK_TYPE ) 0x01; /* R1 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x02; /* R2 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x03; /* R3 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x04; /* R4 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x05; /* R5 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x06; /* R6 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x07; /* R7 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x08; /* R8 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x09; /* R9 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x10; /* R10 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x11; /* R11 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x12; /* R12 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x13; /* R13 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x14; /* R14 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x15; /* R15 */
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pxTopOfStack--;
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/* Place the parameter on the stack in the expected location. */
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usAddress = ( unsigned portSHORT ) pvParameters;
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff );
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pxTopOfStack--;
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usAddress >>= 8;
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*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff );
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x18; /* R18 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x19; /* R19 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x20; /* R20 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x21; /* R21 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x22; /* R22 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x23; /* R23 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x24; /* R24 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x25; /* R25 */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x26; /* R26 X */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x27; /* R27 */
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pxTopOfStack--;
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/* The Y register is not stored as it is used as the software stack and
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gets saved into the task control block. */
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*pxTopOfStack = ( portSTACK_TYPE ) 0x30; /* R30 Z */
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pxTopOfStack--;
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*pxTopOfStack = ( portSTACK_TYPE ) 0x031; /* R31 */
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pxTopOfStack--;
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*pxTopOfStack = portNO_CRITICAL_NESTING; /* Critical nesting is zero when the task starts. */
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/*lint +e950 +e611 +e923 */
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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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/* Setup the hardware to generate the tick. */
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prvSetupTimerInterrupt();
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/* Restore the context of the first task that is going to run.
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Normally we would just call portRESTORE_CONTEXT() here, but as the IAR
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compiler does not fully support inline assembler we have to make a call.*/
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vPortStart();
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/* Should not get here! */
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return pdTRUE;
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}
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/*-----------------------------------------------------------*/
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void vPortEndScheduler( void )
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{
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/* It is unlikely that the AVR port will get stopped. If required simply
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disable the tick interrupt here. */
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}
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/*-----------------------------------------------------------*/
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/*
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* Setup timer 1 compare match A to generate a tick interrupt.
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*/
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static void prvSetupTimerInterrupt( void )
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{
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unsigned portLONG ulCompareMatch;
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unsigned portCHAR ucHighByte, ucLowByte;
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/* Using 16bit timer 1 to generate the tick. Correct fuses must be
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selected for the configCPU_CLOCK_HZ clock. */
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ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ;
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/* We only have 16 bits so have to scale to get our required tick rate. */
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ulCompareMatch /= portCLOCK_PRESCALER;
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/* Adjust for correct value. */
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ulCompareMatch -= ( unsigned portLONG ) 1;
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/* Setup compare match value for compare match A. Interrupts are disabled
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before this is called so we need not worry here. */
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ucLowByte = ( unsigned portCHAR ) ( ulCompareMatch & ( unsigned portLONG ) 0xff );
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ulCompareMatch >>= 8;
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ucHighByte = ( unsigned portCHAR ) ( ulCompareMatch & ( unsigned portLONG ) 0xff );
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OCR1AH = ucHighByte;
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OCR1AL = ucLowByte;
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/* Setup clock source and compare match behaviour. */
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ucLowByte = portCLEAR_COUNTER_ON_MATCH | portPRESCALE_64;
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TCCR1B = ucLowByte;
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/* Enable the interrupt - this is okay as interrupt are currently globally
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disabled. */
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TIMSK |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE;
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}
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/*-----------------------------------------------------------*/
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#if configUSE_PREEMPTION == 1
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/*
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* Tick ISR for preemptive scheduler. We can use a __task attribute as
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* the context is saved at the start of vPortYieldFromTick(). The tick
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* count is incremented after the context is saved.
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*/
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__task void SIG_OUTPUT_COMPARE1A( void )
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{
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vPortYieldFromTick();
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asm( "reti" );
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}
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#else
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/*
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* Tick ISR for the cooperative scheduler. All this does is increment the
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* tick count. We don't need to switch context, this can only be done by
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* manual calls to taskYIELD();
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*
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* THE INTERRUPT VECTOR IS POPULATED IN portmacro.s90. DO NOT INSTALL
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* IT HERE USING THE USUAL PRAGMA.
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*/
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__interrupt void SIG_OUTPUT_COMPARE1A( void )
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{
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vTaskIncrementTick();
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}
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#endif
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/*-----------------------------------------------------------*/
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void vPortEnterCritical( void )
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{
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portDISABLE_INTERRUPTS();
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uxCriticalNesting++;
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}
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/*-----------------------------------------------------------*/
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void vPortExitCritical( void )
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{
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uxCriticalNesting--;
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if( uxCriticalNesting == portNO_CRITICAL_NESTING )
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{
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portENABLE_INTERRUPTS();
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}
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}
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