port.c

FreeRTOSV4.1.0 安裝文件 FreeRTOS 是一个源码公开的免费的嵌入式实时操作系统

		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 portLONG ulAddress;
unsigned portCHAR 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 portLONG ) pvParameters;
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned portLONG ) 0x00ff );
	pxTopOfStack++;

	ulAddress >>= 8;
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned portLONG ) 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 portLONG ) pxCode;

	/* TOS low. */
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned portLONG ) 0x00ff );
	pxTopOfStack++;
	ulAddress >>= 8;

	/* TOS high. */
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned portLONG ) 0x00ff );
	pxTopOfStack++;
	ulAddress >>= 8;

	/* TOS even higher. */
	*pxTopOfStack = ( portSTACK_TYPE ) ( ulAddress & ( unsigned portLONG ) 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 )
{
	/* In this port we ignore the parameter and use the configUSE_PREEMPTION
	definition instead. */

	/* 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. */
	vTaskIncrementTick();

	#if configUSE_PREEMPTION == 1
	{
		/* Switch to the highest priority task that is ready to run. */
		vTaskSwitchContext();
	}
	#endif

	portRESTORE_CONTEXT();
}
/*-----------------------------------------------------------*/

/*
 * Setup a timer for a regular tick.
 */
static void prvSetupTimerInterrupt( void )
{
const unsigned portLONG ulConstCompareValue = ( ( configCPU_CLOCK_HZ / portTIMER_FOSC_SCALE ) / configTICK_RATE_HZ );
unsigned portLONG ulCompareValue;
unsigned portCHAR 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 portCHAR ) 0x00;
	TMR1L = ( unsigned portCHAR ) 0x00;

	/* Set the compare match value. */
	ulCompareValue = ulConstCompareValue;
	CCPR1L = ( unsigned portCHAR ) ( ulCompareValue & ( unsigned portLONG ) 0xff );
	ulCompareValue >>= ( unsigned portLONG ) 8;
	CCPR1H = ( unsigned portCHAR ) ( ulCompareValue & ( unsigned portLONG ) 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 );
}