📄 port.c
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/*
FreeRTOS.org V4.2.1 - Copyright (C) 2003-2007 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 as published by
the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
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 Temple Place, Suite 330, Boston, MA 02111-1307 USA
A special exception to the GPL can be applied should you wish to distribute
a combined work that includes FreeRTOS.org, without being obliged to provide
the source code for any proprietary components. See the licensing section
of http://www.FreeRTOS.org for full details of how and when the exception
can be applied.
***************************************************************************
See http://www.FreeRTOS.org for documentation, latest information, license
and contact details. Please ensure to read the configuration and relevant
port sections of the online documentation.
Also see http://www.SafeRTOS.com for an IEC 61508 compliant version along
with commercial development and support options.
***************************************************************************
*/
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the PIC24 port.
*----------------------------------------------------------*/
/* Scheduler include files. */
#include "FreeRTOS.h"
#include "task.h"
/* Hardware specifics. */
#define portBIT_SET 1
#define portTIMER_PRESCALE 8
#define portINITIAL_SR 0
/* The program counter is only 23 bits. */
#define portUNUSED_PR_BITS 0x7f
/* Records the nesting depth of calls to portENTER_CRITICAL(). */
unsigned portBASE_TYPE uxCriticalNesting = 0xef;
#if configKERNEL_INTERRUPT_PRIORITY != 1
#error If configKERNEL_INTERRUPT_PRIORITY is not 1 then the #32 in the following macros needs changing to equal the portINTERRUPT_BITS value.
#endif
#ifdef MPLAB_PIC24_PORT
#define portRESTORE_CONTEXT() \
asm volatile( "MOV _pxCurrentTCB, W0 \n" /* Restore the stack pointer for the task. */ \
"MOV [W0], W15 \n" \
"POP W0 \n" /* Restore the critical nesting counter for the task. */ \
"MOV W0, _uxCriticalNesting \n" \
"POP PSVPAG \n" \
"POP CORCON \n" \
"POP TBLPAG \n" \
"POP RCOUNT \n" /* Restore the registers from the stack. */ \
"POP W14 \n" \
"POP.D W12 \n" \
"POP.D W10 \n" \
"POP.D W8 \n" \
"POP.D W6 \n" \
"POP.D W4 \n" \
"POP.D W2 \n" \
"POP.D W0 \n" \
"POP SR " );
#define portSAVE_CONTEXT() \
asm volatile( "PUSH SR \n" /* Save the SR used by the task.... */ \
"PUSH W0 \n" /* ....then disable interrupts. */ \
"MOV #32, W0 \n" \
"MOV W0, SR \n" \
"PUSH W1 \n" /* Save registers to the stack. */ \
"PUSH.D W2 \n" \
"PUSH.D W4 \n" \
"PUSH.D W6 \n" \
"PUSH.D W8 \n" \
"PUSH.D W10 \n" \
"PUSH.D W12 \n" \
"PUSH W14 \n" \
"PUSH RCOUNT \n" \
"PUSH TBLPAG \n" \
"PUSH CORCON \n" \
"PUSH PSVPAG \n" \
"MOV _uxCriticalNesting, W0 \n" /* Save the critical nesting counter for the task. */ \
"PUSH W0 \n" \
"MOV _pxCurrentTCB, W0 \n" /* Save the new top of stack into the TCB. */ \
"MOV W15, [W0] ");
#endif /* MPLAB_PIC24_PORT */
#ifdef MPLAB_DSPIC_PORT
#define portRESTORE_CONTEXT() \
asm volatile( "MOV _pxCurrentTCB, W0 \n" /* Restore the stack pointer for the task. */ \
"MOV [W0], W15 \n" \
"POP W0 \n" /* Restore the critical nesting counter for the task. */ \
"MOV W0, _uxCriticalNesting \n" \
"POP PSVPAG \n" \
"POP CORCON \n" \
"POP DOENDH \n" \
"POP DOENDL \n" \
"POP DOSTARTH \n" \
"POP DOSTARTL \n" \
"POP DCOUNT \n" \
"POP ACCBU \n" \
"POP ACCBH \n" \
"POP ACCBL \n" \
"POP ACCAU \n" \
"POP ACCAH \n" \
"POP ACCAL \n" \
"POP TBLPAG \n" \
"POP RCOUNT \n" /* Restore the registers from the stack. */ \
"POP W14 \n" \
"POP.D W12 \n" \
"POP.D W10 \n" \
"POP.D W8 \n" \
"POP.D W6 \n" \
"POP.D W4 \n" \
"POP.D W2 \n" \
"POP.D W0 \n" \
"POP SR " );
#define portSAVE_CONTEXT() \
asm volatile( "PUSH SR \n" /* Save the SR used by the task.... */ \
"PUSH W0 \n" /* ....then disable interrupts. */ \
"MOV #32, W0 \n" \
"MOV W0, SR \n" \
"PUSH W1 \n" /* Save registers to the stack. */ \
"PUSH.D W2 \n" \
"PUSH.D W4 \n" \
"PUSH.D W6 \n" \
"PUSH.D W8 \n" \
"PUSH.D W10 \n" \
"PUSH.D W12 \n" \
"PUSH W14 \n" \
"PUSH RCOUNT \n" \
"PUSH TBLPAG \n" \
"PUSH ACCAL \n" \
"PUSH ACCAH \n" \
"PUSH ACCAU \n" \
"PUSH ACCBL \n" \
"PUSH ACCBH \n" \
"PUSH ACCBU \n" \
"PUSH DCOUNT \n" \
"PUSH DOSTARTL \n" \
"PUSH DOSTARTH \n" \
"PUSH DOENDL \n" \
"PUSH DOENDH \n" \
"PUSH CORCON \n" \
"PUSH PSVPAG \n" \
"MOV _uxCriticalNesting, W0 \n" /* Save the critical nesting counter for the task. */ \
"PUSH W0 \n" \
"MOV _pxCurrentTCB, W0 \n" /* Save the new top of stack into the TCB. */ \
"MOV W15, [W0] " );
#endif /* MPLAB_DSPIC_PORT */
/*
* Setup the timer used to generate the tick interrupt.
*/
static void prvSetupTimerInterrupt( void );
/*
* See header file for description.
*/
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
unsigned portSHORT usCode;
portBASE_TYPE i;
const portSTACK_TYPE xInitialStack[] =
{
0x1111, /* W1 */
0x2222, /* W2 */
0x3333, /* W3 */
0x4444, /* W4 */
0x5555, /* W5 */
0x6666, /* W6 */
0x7777, /* W7 */
0x8888, /* W8 */
0x9999, /* W9 */
0xaaaa, /* W10 */
0xbbbb, /* W11 */
0xcccc, /* W12 */
0xdddd, /* W13 */
0xeeee, /* W14 */
0xcdce, /* RCOUNT */
0xabac, /* TBLPAG */
/* dsPIC specific registers. */
#ifdef MPLAB_DSPIC_PORT
0x0202, /* ACCAL */
0x0303, /* ACCAH */
0x0404, /* ACCAU */
0x0505, /* ACCBL */
0x0606, /* ACCBH */
0x0707, /* ACCBU */
0x0808, /* DCOUNT */
0x090a, /* DOSTARTL */
0x1010, /* DOSTARTH */
0x1110, /* DOENDL */
0x1212, /* DOENDH */
#endif
};
/* Setup the stack as if a yield had occurred.
Save the low bytes of the program counter. */
usCode = ( unsigned portSHORT ) pxCode;
*pxTopOfStack = ( portSTACK_TYPE ) usCode;
pxTopOfStack++;
/* Save the high byte of the program counter. This will always be zero
here as it is passed in a 16bit pointer. If the address is greater than
16 bits then the pointer will point to a jump table. */
*pxTopOfStack = ( portSTACK_TYPE ) 0;
pxTopOfStack++;
/* Status register with interrupts enabled. */
*pxTopOfStack = portINITIAL_SR;
pxTopOfStack++;
/* Parameters are passed in W0. */
*pxTopOfStack = ( portSTACK_TYPE ) pvParameters;
pxTopOfStack++;
for( i = 0; i < ( sizeof( xInitialStack ) / sizeof( portSTACK_TYPE ) ); i++ )
{
*pxTopOfStack = xInitialStack[ i ];
pxTopOfStack++;
}
*pxTopOfStack = CORCON;
pxTopOfStack++;
*pxTopOfStack = PSVPAG;
pxTopOfStack++;
/* Finally the critical nesting depth. */
*pxTopOfStack = 0x00;
pxTopOfStack++;
return pxTopOfStack;
}
/*-----------------------------------------------------------*/
portBASE_TYPE xPortStartScheduler( void )
{
/* Setup a timer for the tick ISR. */
prvSetupTimerInterrupt();
/* Restore the context of the first task to run. */
portRESTORE_CONTEXT();
/* Simulate the end of the yield function. */
asm volatile ( "return" );
/* Should not reach here. */
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 )
{
portSAVE_CONTEXT();
vTaskSwitchContext();
portRESTORE_CONTEXT();
}
/*-----------------------------------------------------------*/
/*
* Setup a timer for a regular tick.
*/
static void prvSetupTimerInterrupt( void )
{
const unsigned portLONG ulCompareMatch = ( configCPU_CLOCK_HZ / portTIMER_PRESCALE ) / configTICK_RATE_HZ;
/* Prescale of 8. */
T1CON = 0;
TMR1 = 0;
PR1 = ( unsigned portSHORT ) ulCompareMatch;
/* Setup timer 1 interrupt priority. */
IPC0bits.T1IP = configKERNEL_INTERRUPT_PRIORITY;
/* Clear the interrupt as a starting condition. */
IFS0bits.T1IF = 0;
/* Enable the interrupt. */
IEC0bits.T1IE = 1;
/* Setup the prescale value. */
T1CONbits.TCKPS0 = 1;
T1CONbits.TCKPS1 = 0;
/* Start the timer. */
T1CONbits.TON = 1;
}
/*-----------------------------------------------------------*/
void vPortEnterCritical( void )
{
portDISABLE_INTERRUPTS();
uxCriticalNesting++;
}
/*-----------------------------------------------------------*/
void vPortExitCritical( void )
{
uxCriticalNesting--;
if( uxCriticalNesting == 0 )
{
portENABLE_INTERRUPTS();
}
}
/*-----------------------------------------------------------*/
void __attribute__((__interrupt__, auto_psv)) _T1Interrupt( void )
{
vTaskIncrementTick();
/* Clear the timer interrupt. */
IFS0bits.T1IF = 0;
#if configUSE_PREEMPTION == 1
portYIELD();
#endif
}
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