/* | |
FreeRTOS.org V5.3.0 - 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 (version 2) as published | |
by the Free Software Foundation and modified by the FreeRTOS exception. | |
**NOTE** The exception to the GPL is included to allow you to distribute a | |
combined work that includes FreeRTOS.org without being obliged to provide | |
the source code for any proprietary components. Alternative commercial | |
license and support terms are also available upon request. See the | |
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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 | |
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*************************************************************************** | |
* * | |
* 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. * | |
* * | |
*************************************************************************** | |
1 tab == 4 spaces! | |
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. | |
*/ | |
#include <stdlib.h> | |
#include "FreeRTOS.h" | |
#include "task.h" | |
/*----------------------------------------------------------- | |
* Implementation of functions defined in portable.h for the AVR/IAR port. | |
*----------------------------------------------------------*/ | |
/* Start tasks with interrupts enables. */ | |
#define portFLAGS_INT_ENABLED ( ( portSTACK_TYPE ) 0x80 ) | |
/* Hardware constants for timer 1. */ | |
#define portCLEAR_COUNTER_ON_MATCH ( ( unsigned portCHAR ) 0x08 ) | |
#define portPRESCALE_64 ( ( unsigned portCHAR ) 0x03 ) | |
#define portCLOCK_PRESCALER ( ( unsigned portLONG ) 64 ) | |
#define portCOMPARE_MATCH_A_INTERRUPT_ENABLE ( ( unsigned portCHAR ) 0x10 ) | |
/* The number of bytes used on the hardware stack by the task start address. */ | |
#define portBYTES_USED_BY_RETURN_ADDRESS ( 2 ) | |
/*-----------------------------------------------------------*/ | |
/* Stores the critical section nesting. This must not be initialised to 0. | |
It will be initialised when a task starts. */ | |
#define portNO_CRITICAL_NESTING ( ( unsigned portBASE_TYPE ) 0 ) | |
unsigned portBASE_TYPE uxCriticalNesting = 0x50; | |
/* | |
* Perform hardware setup to enable ticks from timer 1, compare match A. | |
*/ | |
static void prvSetupTimerInterrupt( void ); | |
/* | |
* The IAR compiler does not have full support for inline assembler, so | |
* these are defined in the portmacro assembler file. | |
*/ | |
extern void vPortYieldFromTick( void ); | |
extern void vPortStart( void ); | |
/*-----------------------------------------------------------*/ | |
/* | |
* See header file for description. | |
*/ | |
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters ) | |
{ | |
unsigned portSHORT usAddress; | |
portSTACK_TYPE *pxTopOfHardwareStack; | |
/* Place a few bytes of known values on the bottom of the stack. | |
This is just useful for debugging. */ | |
*pxTopOfStack = 0x11; | |
pxTopOfStack--; | |
*pxTopOfStack = 0x22; | |
pxTopOfStack--; | |
*pxTopOfStack = 0x33; | |
pxTopOfStack--; | |
/* Remember where the top of the hardware stack is - this is required | |
below. */ | |
pxTopOfHardwareStack = pxTopOfStack; | |
/* Simulate how the stack would look after a call to vPortYield(). */ | |
/*lint -e950 -e611 -e923 Lint doesn't like this much - but nothing I can do about it. */ | |
/* The IAR compiler requires two stacks per task. First there is the | |
hardware call stack which uses the AVR stack pointer. Second there is the | |
software stack (local variables, parameter passing, etc.) which uses the | |
AVR Y register. | |
This function places both stacks within the memory block passed in as the | |
first parameter. The hardware stack is placed at the bottom of the memory | |
block. A gap is then left for the hardware stack to grow. Next the software | |
stack is placed. The amount of space between the software and hardware | |
stacks is defined by configCALL_STACK_SIZE. | |
The first part of the stack is the hardware stack. Place the start | |
address of the task on the hardware stack. */ | |
usAddress = ( unsigned portSHORT ) pxCode; | |
*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff ); | |
pxTopOfStack--; | |
usAddress >>= 8; | |
*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff ); | |
pxTopOfStack--; | |
/* Leave enough space for the hardware stack before starting the software | |
stack. The '- 2' is because we have already used two spaces for the | |
address of the start of the task. */ | |
pxTopOfStack -= ( configCALL_STACK_SIZE - 2 ); | |
/* Next simulate the stack as if after a call to portSAVE_CONTEXT(). | |
portSAVE_CONTEXT places the flags on the stack immediately after r0 | |
to ensure the interrupts get disabled as soon as possible, and so ensuring | |
the stack use is minimal should a context switch interrupt occur. */ | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x00; /* R0 */ | |
pxTopOfStack--; | |
*pxTopOfStack = portFLAGS_INT_ENABLED; | |
pxTopOfStack--; | |
/* Next place the address of the hardware stack. This is required so | |
the AVR stack pointer can be restored to point to the hardware stack. */ | |
pxTopOfHardwareStack -= portBYTES_USED_BY_RETURN_ADDRESS; | |
usAddress = ( unsigned portSHORT ) pxTopOfHardwareStack; | |
/* SPL */ | |
*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff ); | |
pxTopOfStack--; | |
/* SPH */ | |
usAddress >>= 8; | |
*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff ); | |
pxTopOfStack--; | |
/* Now the remaining registers. */ | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x01; /* R1 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x02; /* R2 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x03; /* R3 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x04; /* R4 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x05; /* R5 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x06; /* R6 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x07; /* R7 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x08; /* R8 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x09; /* R9 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x10; /* R10 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x11; /* R11 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x12; /* R12 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x13; /* R13 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x14; /* R14 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x15; /* R15 */ | |
pxTopOfStack--; | |
/* Place the parameter on the stack in the expected location. */ | |
usAddress = ( unsigned portSHORT ) pvParameters; | |
*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff ); | |
pxTopOfStack--; | |
usAddress >>= 8; | |
*pxTopOfStack = ( portSTACK_TYPE ) ( usAddress & ( unsigned portSHORT ) 0x00ff ); | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x18; /* R18 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x19; /* R19 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x20; /* R20 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x21; /* R21 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x22; /* R22 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x23; /* R23 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x24; /* R24 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x25; /* R25 */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x26; /* R26 X */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x27; /* R27 */ | |
pxTopOfStack--; | |
/* The Y register is not stored as it is used as the software stack and | |
gets saved into the task control block. */ | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x30; /* R30 Z */ | |
pxTopOfStack--; | |
*pxTopOfStack = ( portSTACK_TYPE ) 0x031; /* R31 */ | |
pxTopOfStack--; | |
*pxTopOfStack = portNO_CRITICAL_NESTING; /* Critical nesting is zero when the task starts. */ | |
/*lint +e950 +e611 +e923 */ | |
return pxTopOfStack; | |
} | |
/*-----------------------------------------------------------*/ | |
portBASE_TYPE xPortStartScheduler( void ) | |
{ | |
/* Setup the hardware to generate the tick. */ | |
prvSetupTimerInterrupt(); | |
/* Restore the context of the first task that is going to run. | |
Normally we would just call portRESTORE_CONTEXT() here, but as the IAR | |
compiler does not fully support inline assembler we have to make a call.*/ | |
vPortStart(); | |
/* Should not get here! */ | |
return pdTRUE; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortEndScheduler( void ) | |
{ | |
/* It is unlikely that the AVR port will get stopped. If required simply | |
disable the tick interrupt here. */ | |
} | |
/*-----------------------------------------------------------*/ | |
/* | |
* Setup timer 1 compare match A to generate a tick interrupt. | |
*/ | |
static void prvSetupTimerInterrupt( void ) | |
{ | |
unsigned portLONG ulCompareMatch; | |
unsigned portCHAR ucHighByte, ucLowByte; | |
/* Using 16bit timer 1 to generate the tick. Correct fuses must be | |
selected for the configCPU_CLOCK_HZ clock. */ | |
ulCompareMatch = configCPU_CLOCK_HZ / configTICK_RATE_HZ; | |
/* We only have 16 bits so have to scale to get our required tick rate. */ | |
ulCompareMatch /= portCLOCK_PRESCALER; | |
/* Adjust for correct value. */ | |
ulCompareMatch -= ( unsigned portLONG ) 1; | |
/* Setup compare match value for compare match A. Interrupts are disabled | |
before this is called so we need not worry here. */ | |
ucLowByte = ( unsigned portCHAR ) ( ulCompareMatch & ( unsigned portLONG ) 0xff ); | |
ulCompareMatch >>= 8; | |
ucHighByte = ( unsigned portCHAR ) ( ulCompareMatch & ( unsigned portLONG ) 0xff ); | |
OCR1AH = ucHighByte; | |
OCR1AL = ucLowByte; | |
/* Setup clock source and compare match behaviour. */ | |
ucLowByte = portCLEAR_COUNTER_ON_MATCH | portPRESCALE_64; | |
TCCR1B = ucLowByte; | |
/* Enable the interrupt - this is okay as interrupt are currently globally | |
disabled. */ | |
TIMSK |= portCOMPARE_MATCH_A_INTERRUPT_ENABLE; | |
} | |
/*-----------------------------------------------------------*/ | |
#if configUSE_PREEMPTION == 1 | |
/* | |
* Tick ISR for preemptive scheduler. We can use a __task attribute as | |
* the context is saved at the start of vPortYieldFromTick(). The tick | |
* count is incremented after the context is saved. | |
*/ | |
__task void SIG_OUTPUT_COMPARE1A( void ) | |
{ | |
vPortYieldFromTick(); | |
asm( "reti" ); | |
} | |
#else | |
/* | |
* Tick ISR for the cooperative scheduler. All this does is increment the | |
* tick count. We don't need to switch context, this can only be done by | |
* manual calls to taskYIELD(); | |
* | |
* THE INTERRUPT VECTOR IS POPULATED IN portmacro.s90. DO NOT INSTALL | |
* IT HERE USING THE USUAL PRAGMA. | |
*/ | |
__interrupt void SIG_OUTPUT_COMPARE1A( void ) | |
{ | |
vTaskIncrementTick(); | |
} | |
#endif | |
/*-----------------------------------------------------------*/ | |
void vPortEnterCritical( void ) | |
{ | |
portDISABLE_INTERRUPTS(); | |
uxCriticalNesting++; | |
} | |
/*-----------------------------------------------------------*/ | |
void vPortExitCritical( void ) | |
{ | |
uxCriticalNesting--; | |
if( uxCriticalNesting == portNO_CRITICAL_NESTING ) | |
{ | |
portENABLE_INTERRUPTS(); | |
} | |
} | |