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|
/*
FreeRTOS V7.5.0 - Copyright (C) 2013 Real Time Engineers Ltd.
VISIT http://www.FreeRTOS.org TO ENSURE YOU ARE USING THE LATEST VERSION.
***************************************************************************
* *
* FreeRTOS provides completely free yet professionally developed, *
* robust, strictly quality controlled, supported, and cross *
* platform software that has become a de facto standard. *
* *
* Help yourself get started quickly and support the FreeRTOS *
* project by purchasing a FreeRTOS tutorial book, reference *
* manual, or both from: http://www.FreeRTOS.org/Documentation *
* *
* Thank you! *
* *
***************************************************************************
This file is part of the FreeRTOS distribution.
FreeRTOS 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 modification to the GPL is included to allow you to distribute
>>! a combined work that includes FreeRTOS without being obliged to provide
>>! the source code for proprietary components outside of the FreeRTOS
>>! kernel.
FreeRTOS 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. Full license text is available from the following
link: http://www.freertos.org/a00114.html
1 tab == 4 spaces!
***************************************************************************
* *
* Having a problem? Start by reading the FAQ "My application does *
* not run, what could be wrong?" *
* *
* http://www.FreeRTOS.org/FAQHelp.html *
* *
***************************************************************************
http://www.FreeRTOS.org - Documentation, books, training, latest versions,
license and Real Time Engineers Ltd. contact details.
http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool, a DOS
compatible FAT file system, and our tiny thread aware UDP/IP stack.
http://www.OpenRTOS.com - Real Time Engineers ltd license FreeRTOS to High
Integrity Systems to sell under the OpenRTOS brand. Low cost OpenRTOS
licenses offer ticketed support, indemnification and middleware.
http://www.SafeRTOS.com - High Integrity Systems also provide a safety
engineered and independently SIL3 certified version for use in safety and
mission critical applications that require provable dependability.
1 tab == 4 spaces!
*/
/*
Changes between V1.2.4 and V1.2.5
+ Introduced portGLOBAL_INTERRUPT_FLAG definition to test the global
interrupt flag setting. Using the two bits defined within
portINITAL_INTERRUPT_STATE was causing the w register to get clobbered
before the test was performed.
Changes from V1.2.5
+ Set the interrupt vector address to 0x08. Previously it was at the
incorrect address for compatibility mode of 0x18.
Changes from V2.1.1
+ PCLATU and PCLATH are now saved as part of the context. This allows
function pointers to be used within tasks. Thanks to Javier Espeche
for the enhancement.
Changes from V2.3.1
+ TABLAT is now saved as part of the task context.
Changes from V3.2.0
+ TBLPTRU is now initialised to zero as the MPLAB compiler expects this
value and does not write to the register.
*/
/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
/* MPLAB library include file. */
#include "timers.h"
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the PIC port.
*----------------------------------------------------------*/
/* Hardware setup for tick. */
#define portTIMER_FOSC_SCALE ( ( unsigned long ) 4 )
/* Initial interrupt enable state for newly created tasks. This value is
copied into INTCON when a task switches in for the first time. */
#define portINITAL_INTERRUPT_STATE 0xc0
/* Just the bit within INTCON for the global interrupt flag. */
#define portGLOBAL_INTERRUPT_FLAG 0x80
/* Constant used for context switch macro when we require the interrupt
enable state to be unchanged when the interrupted task is switched back in. */
#define portINTERRUPTS_UNCHANGED 0x00
/* Some memory areas get saved as part of the task context. These memory
area's get used by the compiler for temporary storage, especially when
performing mathematical operations, or when using 32bit data types. This
constant defines the size of memory area which must be saved. */
#define portCOMPILER_MANAGED_MEMORY_SIZE ( ( unsigned char ) 0x13 )
/* We require the address of the pxCurrentTCB variable, but don't want to know
any details of its type. */
typedef void tskTCB;
extern volatile tskTCB * volatile pxCurrentTCB;
/* IO port constants. */
#define portBIT_SET ( ( unsigned char ) 1 )
#define portBIT_CLEAR ( ( unsigned char ) 0 )
/*
* The serial port ISR's are defined in serial.c, but are called from portable
* as they use the same vector as the tick ISR.
*/
void vSerialTxISR( void );
void vSerialRxISR( void );
/*
* Perform hardware setup to enable ticks.
*/
static void prvSetupTimerInterrupt( void );
/*
* ISR to maintain the tick, and perform tick context switches if the
* preemptive scheduler is being used.
*/
static void prvTickISR( void );
/*
* ISR placed on the low priority vector. This calls the appropriate ISR for
* the actual interrupt.
*/
static void prvLowInterrupt( void );
/*
* Macro that pushes all the registers that make up the context of a task onto
* the stack, then saves the new top of stack into the TCB.
*
* If this is called from an ISR then the interrupt enable bits must have been
* set for the ISR to ever get called. Therefore we want to save the INTCON
* register with the enable bits forced to be set - and ucForcedInterruptFlags
* must contain these bit settings. This means the interrupts will again be
* enabled when the interrupted task is switched back in.
*
* If this is called from a manual context switch (i.e. from a call to yield),
* then we want to save the INTCON so it is restored with its current state,
* and ucForcedInterruptFlags must be 0. This allows a yield from within
* a critical section.
*
* The compiler uses some locations at the bottom of the memory for temporary
* storage during math and other computations. This is especially true if
* 32bit data types are utilised (as they are by the scheduler). The .tmpdata
* and MATH_DATA sections have to be stored in there entirety as part of a task
* context. This macro stores from data address 0x00 to
* portCOMPILER_MANAGED_MEMORY_SIZE. This is sufficient for the demo
* applications but you should check the map file for your project to ensure
* this is sufficient for your needs. It is not clear whether this size is
* fixed for all compilations or has the potential to be program specific.
*/
#define portSAVE_CONTEXT( ucForcedInterruptFlags ) \
{ \
_asm \
/* Save the status and WREG registers first, as these will get modified \
by the operations below. */ \
MOVFF WREG, PREINC1 \
MOVFF STATUS, PREINC1 \
/* Save the INTCON register with the appropriate bits forced if \
necessary - as described above. */ \
MOVFF INTCON, WREG \
IORLW ucForcedInterruptFlags \
MOVFF WREG, PREINC1 \
_endasm \
\
portDISABLE_INTERRUPTS(); \
\
_asm \
/* Store the necessary registers to the stack. */ \
MOVFF BSR, PREINC1 \
MOVFF FSR2L, PREINC1 \
MOVFF FSR2H, PREINC1 \
MOVFF FSR0L, PREINC1 \
MOVFF FSR0H, PREINC1 \
MOVFF TABLAT, PREINC1 \
MOVFF TBLPTRU, PREINC1 \
MOVFF TBLPTRH, PREINC1 \
MOVFF TBLPTRL, PREINC1 \
MOVFF PRODH, PREINC1 \
MOVFF PRODL, PREINC1 \
MOVFF PCLATU, PREINC1 \
MOVFF PCLATH, PREINC1 \
/* Store the .tempdata and MATH_DATA areas as described above. */ \
CLRF FSR0L, 0 \
CLRF FSR0H, 0 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF POSTINC0, PREINC1 \
MOVFF INDF0, PREINC1 \
MOVFF FSR0L, PREINC1 \
MOVFF FSR0H, PREINC1 \
/* Store the hardware stack pointer in a temp register before we \
modify it. */ \
MOVFF STKPTR, FSR0L \
_endasm \
\
/* Store each address from the hardware stack. */ \
while( STKPTR > ( unsigned char ) 0 ) \
{ \
_asm \
MOVFF TOSL, PREINC1 \
MOVFF TOSH, PREINC1 \
MOVFF TOSU, PREINC1 \
POP \
_endasm \
} \
\
_asm \
/* Store the number of addresses on the hardware stack (from the \
temporary register). */ \
MOVFF FSR0L, PREINC1 \
MOVF PREINC1, 1, 0 \
_endasm \
\
/* Save the new top of the software stack in the TCB. */ \
_asm \
MOVFF pxCurrentTCB, FSR0L \
MOVFF pxCurrentTCB + 1, FSR0H \
MOVFF FSR1L, POSTINC0 \
MOVFF FSR1H, POSTINC0 \
_endasm \
}
/*-----------------------------------------------------------*/
/*
* This is the reverse of portSAVE_CONTEXT. See portSAVE_CONTEXT for more
* details.
*/
#define portRESTORE_CONTEXT() \
{ \
_asm \
/* Set FSR0 to point to pxCurrentTCB->pxTopOfStack. */ \
MOVFF pxCurrentTCB, FSR0L \
MOVFF pxCurrentTCB + 1, FSR0H \
\
/* De-reference FSR0 to set the address it holds into FSR1. \
(i.e. *( pxCurrentTCB->pxTopOfStack ) ). */ \
MOVFF POSTINC0, FSR1L \
MOVFF POSTINC0, FSR1H \
\
/* How many return addresses are there on the hardware stack? Discard \
the first byte as we are pointing to the next free space. */ \
MOVFF POSTDEC1, FSR0L \
MOVFF POSTDEC1, FSR0L \
_endasm \
\
/* Fill the hardware stack from our software stack. */ \
STKPTR = 0; \
\
while( STKPTR < FSR0L ) \
{ \
_asm \
PUSH \
MOVF POSTDEC1, 0, 0 \
MOVWF TOSU, 0 \
MOVF POSTDEC1, 0, 0 \
MOVWF TOSH, 0 \
MOVF POSTDEC1, 0, 0 \
MOVWF TOSL, 0 \
_endasm \
} \
\
_asm \
/* Restore the .tmpdata and MATH_DATA memory. */ \
MOVFF POSTDEC1, FSR0H \
MOVFF POSTDEC1, FSR0L \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, POSTDEC0 \
MOVFF POSTDEC1, INDF0 \
/* Restore the other registers forming the tasks context. */ \
MOVFF POSTDEC1, PCLATH \
MOVFF POSTDEC1, PCLATU \
MOVFF POSTDEC1, PRODL \
MOVFF POSTDEC1, PRODH \
MOVFF POSTDEC1, TBLPTRL \
MOVFF POSTDEC1, TBLPTRH \
MOVFF POSTDEC1, TBLPTRU \
MOVFF POSTDEC1, TABLAT \
MOVFF POSTDEC1, FSR0H \
MOVFF POSTDEC1, FSR0L \
MOVFF POSTDEC1, FSR2H \
MOVFF POSTDEC1, FSR2L \
MOVFF POSTDEC1, BSR \
/* The next byte is the INTCON register. Read this into WREG as some \
manipulation is required. */ \
MOVFF POSTDEC1, WREG \
_endasm \
\
/* From the INTCON register, only the interrupt enable bits form part \
of the tasks context. It is perfectly legitimate for another task to \
have modified any other bits. We therefore only restore the top two bits. \
*/ \
if( WREG & portGLOBAL_INTERRUPT_FLAG ) \
{ \
_asm \
MOVFF POSTDEC1, STATUS \
MOVFF POSTDEC1, WREG \
/* Return enabling interrupts. */ \
RETFIE 0 \
_endasm \
} \
else \
{ \
_asm \
MOVFF POSTDEC1, STATUS \
MOVFF POSTDEC1, WREG \
/* Return without effecting interrupts. The context may have \
been saved from a critical region. */ \
RETURN 0 \
_endasm \
} \
}
/*-----------------------------------------------------------*/
/*
* See header file for description.
*/
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
unsigned long ulAddress;
unsigned char ucBlock;
/* 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++;
/* Simulate how the stack would look after a call to vPortYield() generated
by the compiler.
First store the function parameters. This is where the task will expect to
find them when it starts running. */
ulAddress = ( unsigned long ) pvParameters;
*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned long ) 0x00ff );
pxTopOfStack++;
ulAddress >>= 8;
*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned long ) 0x00ff );
pxTopOfStack++;
/* Next we just leave a space. When a context is saved the stack pointer
is incremented before it is used so as not to corrupt whatever the stack
pointer is actually pointing to. This is especially necessary during
function epilogue code generated by the compiler. */
*pxTopOfStack = 0x44;
pxTopOfStack++;
/* Next are all the registers that form part of the task context. */
*pxTopOfStack = ( portSTACK_TYPE ) 0x66; /* WREG. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0xcc; /* Status. */
pxTopOfStack++;
/* INTCON is saved with interrupts enabled. */
*pxTopOfStack = ( portSTACK_TYPE ) portINITAL_INTERRUPT_STATE; /* INTCON */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x11; /* BSR. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x22; /* FSR2L. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x33; /* FSR2H. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x44; /* FSR0L. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x55; /* FSR0H. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x66; /* TABLAT. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x00; /* TBLPTRU. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x88; /* TBLPTRUH. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x99; /* TBLPTRUL. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0xaa; /* PRODH. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0xbb; /* PRODL. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x00; /* PCLATU. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x00; /* PCLATH. */
pxTopOfStack++;
/* Next the .tmpdata and MATH_DATA sections. */
for( ucBlock = 0; ucBlock <= portCOMPILER_MANAGED_MEMORY_SIZE; ucBlock++ )
{
*pxTopOfStack = ( portSTACK_TYPE ) ucBlock;
*pxTopOfStack++;
}
/* Store the top of the global data section. */
*pxTopOfStack = ( portSTACK_TYPE ) portCOMPILER_MANAGED_MEMORY_SIZE; /* Low. */
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) 0x00; /* High. */
pxTopOfStack++;
/* The only function return address so far is the address of the
task. */
ulAddress = ( unsigned long ) pxCode;
/* TOS low. */
*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned long ) 0x00ff );
pxTopOfStack++;
ulAddress >>= 8;
/* TOS high. */
*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned long ) 0x00ff );
pxTopOfStack++;
ulAddress >>= 8;
/* TOS even higher. */
*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned long ) 0x00ff );
pxTopOfStack++;
/* Store the number of return addresses on the hardware stack - so far only
the address of the task entry point. */
*pxTopOfStack = ( portSTACK_TYPE ) 1;
pxTopOfStack++;
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
portBASE_TYPE xPortStartScheduler( void )
{
/* Setup a timer for the tick ISR is using the preemptive scheduler. */
prvSetupTimerInterrupt();
/* Restore the context of the first task to run. */
portRESTORE_CONTEXT();
/* Should not get here. Use the function name to stop compiler warnings. */
( void ) prvLowInterrupt;
( void ) prvTickISR;
return pdTRUE;
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* It is unlikely that the scheduler for the PIC port will get stopped
once running. If required disable the tick interrupt here, then return
to xPortStartScheduler(). */
}
/*-----------------------------------------------------------*/
/*
* Manual context switch. This is similar to the tick context switch,
* but does not increment the tick count. It must be identical to the
* tick context switch in how it stores the stack of a task.
*/
void vPortYield( void )
{
/* This can get called with interrupts either enabled or disabled. We
will save the INTCON register with the interrupt enable bits unmodified. */
portSAVE_CONTEXT( portINTERRUPTS_UNCHANGED );
/* Switch to the highest priority task that is ready to run. */
vTaskSwitchContext();
/* Start executing the task we have just switched to. */
portRESTORE_CONTEXT();
}
/*-----------------------------------------------------------*/
/*
* Vector for ISR. Nothing here must alter any registers!
*/
#pragma code high_vector=0x08
static void prvLowInterrupt( void )
{
/* Was the interrupt the tick? */
if( PIR1bits.CCP1IF )
{
_asm
goto prvTickISR
_endasm
}
/* Was the interrupt a byte being received? */
if( PIR1bits.RCIF )
{
_asm
goto vSerialRxISR
_endasm
}
/* Was the interrupt the Tx register becoming empty? */
if( PIR1bits.TXIF )
{
if( PIE1bits.TXIE )
{
_asm
goto vSerialTxISR
_endasm
}
}
}
#pragma code
/*-----------------------------------------------------------*/
/*
* ISR for the tick.
* This increments the tick count and, if using the preemptive scheduler,
* performs a context switch. This must be identical to the manual
* context switch in how it stores the context of a task.
*/
static void prvTickISR( void )
{
/* Interrupts must have been enabled for the ISR to fire, so we have to
save the context with interrupts enabled. */
portSAVE_CONTEXT( portGLOBAL_INTERRUPT_FLAG );
PIR1bits.CCP1IF = 0;
/* Maintain the tick count. */
if( xTaskIncrementTick() != pdFALSE )
{
/* Switch to the highest priority task that is ready to run. */
vTaskSwitchContext();
}
portRESTORE_CONTEXT();
}
/*-----------------------------------------------------------*/
/*
* Setup a timer for a regular tick.
*/
static void prvSetupTimerInterrupt( void )
{
const unsigned long ulConstCompareValue = ( ( configCPU_CLOCK_HZ / portTIMER_FOSC_SCALE ) / configTICK_RATE_HZ );
unsigned long ulCompareValue;
unsigned char ucByte;
/* Interrupts are disabled when this function is called.
Setup CCP1 to provide the tick interrupt using a compare match on timer
1.
Clear the time count then setup timer. */
TMR1H = ( unsigned char ) 0x00;
TMR1L = ( unsigned char ) 0x00;
/* Set the compare match value. */
ulCompareValue = ulConstCompareValue;
CCPR1L = ( unsigned char ) ( ulCompareValue & ( unsigned long ) 0xff );
ulCompareValue >>= ( unsigned long ) 8;
CCPR1H = ( unsigned char ) ( ulCompareValue & ( unsigned long ) 0xff );
CCP1CONbits.CCP1M0 = portBIT_SET; /*< Compare match mode. */
CCP1CONbits.CCP1M1 = portBIT_SET; /*< Compare match mode. */
CCP1CONbits.CCP1M2 = portBIT_CLEAR; /*< Compare match mode. */
CCP1CONbits.CCP1M3 = portBIT_SET; /*< Compare match mode. */
PIE1bits.CCP1IE = portBIT_SET; /*< Interrupt enable. */
/* We are only going to use the global interrupt bit, so set the peripheral
bit to true. */
INTCONbits.GIEL = portBIT_SET;
/* Provided library function for setting up the timer that will produce the
tick. */
OpenTimer1( T1_16BIT_RW & T1_SOURCE_INT & T1_PS_1_1 & T1_CCP1_T3_CCP2 );
}
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