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/*
FreeRTOS V7.2.0 - Copyright (C) 2012 Real Time Engineers Ltd.
***************************************************************************
* *
* FreeRTOS tutorial books are available in pdf and paperback. *
* Complete, revised, and edited pdf reference manuals are also *
* available. *
* *
* Purchasing FreeRTOS documentation will not only help you, by *
* ensuring you get running as quickly as possible and with an *
* in-depth knowledge of how to use FreeRTOS, it will also help *
* the FreeRTOS project to continue with its mission of providing *
* professional grade, cross platform, de facto standard solutions *
* for microcontrollers - completely free of charge! *
* *
* >>> See http://www.FreeRTOS.org/Documentation for details. <<< *
* *
* Thank you for using FreeRTOS, and thank you for your support! *
* *
***************************************************************************
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. See the GNU General Public License for
more details. You should have received a copy of the GNU General Public
License and the FreeRTOS license exception along with FreeRTOS; if not it
can be viewed here: http://www.freertos.org/a00114.html and also obtained
by writing to Richard Barry, contact details for whom are available on the
FreeRTOS WEB site.
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, training, latest information,
license and contact details.
http://www.FreeRTOS.org/plus - A selection of FreeRTOS ecosystem products,
including FreeRTOS+Trace - an indispensable productivity tool.
Real Time Engineers ltd license FreeRTOS to High Integrity Systems, who sell
the code with commercial support, indemnification, and middleware, under
the OpenRTOS brand: http://www.OpenRTOS.com. High Integrity Systems also
provide a safety engineered and independently SIL3 certified version under
the SafeRTOS brand: http://www.SafeRTOS.com.
*/
/*-----------------------------------------------------------
* Implementation of functions defined in portable.h for the Cygnal port.
*----------------------------------------------------------*/
/* Standard includes. */
#include <string.h>
/* Scheduler includes. */
#include "FreeRTOS.h"
#include "task.h"
/* Constants required to setup timer 2 to produce the RTOS tick. */
#define portCLOCK_DIVISOR ( ( unsigned long ) 12 )
#define portMAX_TIMER_VALUE ( ( unsigned long ) 0xffff )
#define portENABLE_TIMER ( ( unsigned char ) 0x04 )
#define portTIMER_2_INTERRUPT_ENABLE ( ( unsigned char ) 0x20 )
/* The value used in the IE register when a task first starts. */
#define portGLOBAL_INTERRUPT_BIT ( ( portSTACK_TYPE ) 0x80 )
/* The value used in the PSW register when a task first starts. */
#define portINITIAL_PSW ( ( portSTACK_TYPE ) 0x00 )
/* Macro to clear the timer 2 interrupt flag. */
#define portCLEAR_INTERRUPT_FLAG() TMR2CN &= ~0x80;
/* Used during a context switch to store the size of the stack being copied
to or from XRAM. */
data static unsigned char ucStackBytes;
/* Used during a context switch to point to the next byte in XRAM from/to which
a RAM byte is to be copied. */
xdata static portSTACK_TYPE * data pxXRAMStack;
/* Used during a context switch to point to the next byte in RAM from/to which
an XRAM byte is to be copied. */
data static portSTACK_TYPE * data pxRAMStack;
/* 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;
/*
* Setup the hardware to generate an interrupt off timer 2 at the required
* frequency.
*/
static void prvSetupTimerInterrupt( void );
/*-----------------------------------------------------------*/
/*
* Macro that copies the current stack from internal RAM to XRAM. This is
* required as the 8051 only contains enough internal RAM for a single stack,
* but we have a stack for every task.
*/
#define portCOPY_STACK_TO_XRAM() \
{ \
/* pxCurrentTCB points to a TCB which itself points to the location into \
which the first stack byte should be copied. Set pxXRAMStack to point \
to the location into which the first stack byte is to be copied. */ \
pxXRAMStack = ( xdata portSTACK_TYPE * ) *( ( xdata portSTACK_TYPE ** ) pxCurrentTCB ); \
\
/* Set pxRAMStack to point to the first byte to be coped from the stack. */ \
pxRAMStack = ( data portSTACK_TYPE * data ) configSTACK_START; \
\
/* Calculate the size of the stack we are about to copy from the current \
stack pointer value. */ \
ucStackBytes = SP - ( configSTACK_START - 1 ); \
\
/* Before starting to copy the stack, store the calculated stack size so \
the stack can be restored when the task is resumed. */ \
*pxXRAMStack = ucStackBytes; \
\
/* Copy each stack byte in turn. pxXRAMStack is incremented first as we \
have already stored the stack size into XRAM. */ \
while( ucStackBytes ) \
{ \
pxXRAMStack++; \
*pxXRAMStack = *pxRAMStack; \
pxRAMStack++; \
ucStackBytes--; \
} \
}
/*-----------------------------------------------------------*/
/*
* Macro that copies the stack of the task being resumed from XRAM into
* internal RAM.
*/
#define portCOPY_XRAM_TO_STACK() \
{ \
/* Setup the pointers as per portCOPY_STACK_TO_XRAM(), but this time to \
copy the data back out of XRAM and into the stack. */ \
pxXRAMStack = ( xdata portSTACK_TYPE * ) *( ( xdata portSTACK_TYPE ** ) pxCurrentTCB ); \
pxRAMStack = ( data portSTACK_TYPE * data ) ( configSTACK_START - 1 ); \
\
/* The first value stored in XRAM was the size of the stack - i.e. the \
number of bytes we need to copy back. */ \
ucStackBytes = pxXRAMStack[ 0 ]; \
\
/* Copy the required number of bytes back into the stack. */ \
do \
{ \
pxXRAMStack++; \
pxRAMStack++; \
*pxRAMStack = *pxXRAMStack; \
ucStackBytes--; \
} while( ucStackBytes ); \
\
/* Restore the stack pointer ready to use the restored stack. */ \
SP = ( unsigned char ) pxRAMStack; \
}
/*-----------------------------------------------------------*/
/*
* Macro to push the current execution context onto the stack, before the stack
* is moved to XRAM.
*/
#define portSAVE_CONTEXT() \
{ \
_asm \
/* Push ACC first, as when restoring the context it must be restored \
last (it is used to set the IE register). */ \
push ACC \
/* Store the IE register then disable interrupts. */ \
push IE \
clr _EA \
push DPL \
push DPH \
push b \
push ar2 \
push ar3 \
push ar4 \
push ar5 \
push ar6 \
push ar7 \
push ar0 \
push ar1 \
push PSW \
_endasm; \
PSW = 0; \
_asm \
push _bp \
_endasm; \
}
/*-----------------------------------------------------------*/
/*
* Macro that restores the execution context from the stack. The execution
* context was saved into the stack before the stack was copied into XRAM.
*/
#define portRESTORE_CONTEXT() \
{ \
_asm \
pop _bp \
pop PSW \
pop ar1 \
pop ar0 \
pop ar7 \
pop ar6 \
pop ar5 \
pop ar4 \
pop ar3 \
pop ar2 \
pop b \
pop DPH \
pop DPL \
/* The next byte of the stack is the IE register. Only the global \
enable bit forms part of the task context. Pop off the IE then set \
the global enable bit to match that of the stored IE register. */ \
pop ACC \
JB ACC.7,0098$ \
CLR IE.7 \
LJMP 0099$ \
0098$: \
SETB IE.7 \
0099$: \
/* Finally pop off the ACC, which was the first register saved. */ \
pop ACC \
reti \
_endasm; \
}
/*-----------------------------------------------------------*/
/*
* See header file for description.
*/
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
unsigned long ulAddress;
portSTACK_TYPE *pxStartOfStack;
/* Leave space to write the size of the stack as the first byte. */
pxStartOfStack = pxTopOfStack;
pxTopOfStack++;
/* Place a few bytes of known values on the bottom of the stack.
This is just useful for debugging and can be uncommented if required.
*pxTopOfStack = 0x11;
pxTopOfStack++;
*pxTopOfStack = 0x22;
pxTopOfStack++;
*pxTopOfStack = 0x33;
pxTopOfStack++;
*/
/* Simulate how the stack would look after a call to the scheduler tick
ISR.
The return address that would have been pushed by the MCU. */
ulAddress = ( unsigned long ) pxCode;
*pxTopOfStack = ( portSTACK_TYPE ) ulAddress;
ulAddress >>= 8;
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress );
pxTopOfStack++;
/* Next all the registers will have been pushed by portSAVE_CONTEXT(). */
*pxTopOfStack = 0xaa; /* acc */
pxTopOfStack++;
/* We want tasks to start with interrupts enabled. */
*pxTopOfStack = portGLOBAL_INTERRUPT_BIT;
pxTopOfStack++;
/* The function parameters will be passed in the DPTR and B register as
a three byte generic pointer is used. */
ulAddress = ( unsigned long ) pvParameters;
*pxTopOfStack = ( portSTACK_TYPE ) ulAddress; /* DPL */
ulAddress >>= 8;
*pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) ulAddress; /* DPH */
ulAddress >>= 8;
pxTopOfStack++;
*pxTopOfStack = ( portSTACK_TYPE ) ulAddress; /* b */
pxTopOfStack++;
/* The remaining registers are straight forward. */
*pxTopOfStack = 0x02; /* R2 */
pxTopOfStack++;
*pxTopOfStack = 0x03; /* R3 */
pxTopOfStack++;
*pxTopOfStack = 0x04; /* R4 */
pxTopOfStack++;
*pxTopOfStack = 0x05; /* R5 */
pxTopOfStack++;
*pxTopOfStack = 0x06; /* R6 */
pxTopOfStack++;
*pxTopOfStack = 0x07; /* R7 */
pxTopOfStack++;
*pxTopOfStack = 0x00; /* R0 */
pxTopOfStack++;
*pxTopOfStack = 0x01; /* R1 */
pxTopOfStack++;
*pxTopOfStack = 0x00; /* PSW */
pxTopOfStack++;
*pxTopOfStack = 0xbb; /* BP */
/* Dont increment the stack size here as we don't want to include
the stack size byte as part of the stack size count.
Finally we place the stack size at the beginning. */
*pxStartOfStack = ( portSTACK_TYPE ) ( pxTopOfStack - pxStartOfStack );
/* Unlike most ports, we return the start of the stack as this is where the
size of the stack is stored. */
return pxStartOfStack;
}
/*-----------------------------------------------------------*/
/*
* See header file for description.
*/
portBASE_TYPE xPortStartScheduler( void )
{
/* Setup timer 2 to generate the RTOS tick. */
prvSetupTimerInterrupt();
/* Make sure we start with the expected SFR page. This line should not
really be required. */
SFRPAGE = 0;
/* Copy the stack for the first task to execute from XRAM into the stack,
restore the task context from the new stack, then start running the task. */
portCOPY_XRAM_TO_STACK();
portRESTORE_CONTEXT();
/* Should never get here! */
return pdTRUE;
}
/*-----------------------------------------------------------*/
void vPortEndScheduler( void )
{
/* Not implemented for this port. */
}
/*-----------------------------------------------------------*/
/*
* Manual context switch. The first thing we do is save the registers so we
* can use a naked attribute.
*/
void vPortYield( void ) _naked
{
/* Save the execution context onto the stack, then copy the entire stack
to XRAM. This is necessary as the internal RAM is only large enough to
hold one stack, and we want one per task.
PERFORMANCE COULD BE IMPROVED BY ONLY COPYING TO XRAM IF A TASK SWITCH
IS REQUIRED. */
portSAVE_CONTEXT();
portCOPY_STACK_TO_XRAM();
/* Call the standard scheduler context switch function. */
vTaskSwitchContext();
/* Copy the stack of the task about to execute from XRAM into RAM and
restore it's context ready to run on exiting. */
portCOPY_XRAM_TO_STACK();
portRESTORE_CONTEXT();
}
/*-----------------------------------------------------------*/
#if configUSE_PREEMPTION == 1
void vTimer2ISR( void ) interrupt 5 _naked
{
/* Preemptive context switch function triggered by the timer 2 ISR.
This does the same as vPortYield() (see above) with the addition
of incrementing the RTOS tick count. */
portSAVE_CONTEXT();
portCOPY_STACK_TO_XRAM();
vTaskIncrementTick();
vTaskSwitchContext();
portCLEAR_INTERRUPT_FLAG();
portCOPY_XRAM_TO_STACK();
portRESTORE_CONTEXT();
}
#else
void vTimer2ISR( void ) interrupt 5
{
/* When using the cooperative scheduler the timer 2 ISR is only
required to increment the RTOS tick count. */
vTaskIncrementTick();
portCLEAR_INTERRUPT_FLAG();
}
#endif
/*-----------------------------------------------------------*/
static void prvSetupTimerInterrupt( void )
{
unsigned char ucOriginalSFRPage;
/* Constants calculated to give the required timer capture values. */
const unsigned long ulTicksPerSecond = configCPU_CLOCK_HZ / portCLOCK_DIVISOR;
const unsigned long ulCaptureTime = ulTicksPerSecond / configTICK_RATE_HZ;
const unsigned long ulCaptureValue = portMAX_TIMER_VALUE - ulCaptureTime;
const unsigned char ucLowCaptureByte = ( unsigned char ) ( ulCaptureValue & ( unsigned long ) 0xff );
const unsigned char ucHighCaptureByte = ( unsigned char ) ( ulCaptureValue >> ( unsigned long ) 8 );
/* NOTE: This uses a timer only present on 8052 architecture. */
/* Remember the current SFR page so we can restore it at the end of the
function. */
ucOriginalSFRPage = SFRPAGE;
SFRPAGE = 0;
/* TMR2CF can be left in its default state. */
TMR2CF = ( unsigned char ) 0;
/* Setup the overflow reload value. */
RCAP2L = ucLowCaptureByte;
RCAP2H = ucHighCaptureByte;
/* The initial load is performed manually. */
TMR2L = ucLowCaptureByte;
TMR2H = ucHighCaptureByte;
/* Enable the timer 2 interrupts. */
IE |= portTIMER_2_INTERRUPT_ENABLE;
/* Interrupts are disabled when this is called so the timer can be started
here. */
TMR2CN = portENABLE_TIMER;
/* Restore the original SFR page. */
SFRPAGE = ucOriginalSFRPage;
}