port.c

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    MOV A, DTB
    SWAP
    MOV A, PCB
    ORW A
	#if configMEMMODEL == portMEDIUM || configMEMMODEL == portLARGE
		RETP
	#elif configMEMMODEL == portSMALL || configMEMMODEL == portCOMPACT   
		RET
	#endif 

#pragma endasm
/*-----------------------------------------------------------*/

/* 
 * Initialise the stack of a task to look exactly as if a call to 
 * portSAVE_CONTEXT had been called.
 * 
 * See the header file portable.h.
 */
portSTACK_TYPE *pxPortInitialiseStack( portSTACK_TYPE *pxTopOfStack, pdTASK_CODE pxCode, void *pvParameters )
{
	/* Place a few bytes of known values on the bottom of the stack. 
	This is just useful for debugging. */
	*pxTopOfStack = 0x1111;
	pxTopOfStack--;
	*pxTopOfStack = 0x2222;
	pxTopOfStack--;
	*pxTopOfStack = 0x3333;
	pxTopOfStack--;

	/* Once the task is called the task  would  push  the  pointer to the
	parameter onto the stack. Hence here the pointer would be copied to the stack
	first.  When using the COMPACT or LARGE memory model the pointer would be 24 
	bits, and when using the SMALL or MEDIUM memory model the pointer would be 16 
	bits. */ 
	#if( ( configMEMMODEL == portCOMPACT ) || ( configMEMMODEL == portLARGE ) )
	{
		*pxTopOfStack = ( portSTACK_TYPE ) ( ( unsigned portLONG ) ( pvParameters ) >> 16 );
		pxTopOfStack--;         
	}
	#endif

    *pxTopOfStack = ( portSTACK_TYPE ) ( pvParameters );
    pxTopOfStack--;                  
    
    /* This is redundant push to the stack. This is required in order to introduce 
    an offset so that the task accesses a parameter correctly that is passed on to 
    the task stack. */
	#if( ( configMEMMODEL == portMEDIUM ) || ( configMEMMODEL == portLARGE ) )
	{
		*pxTopOfStack = ( xGet_DTB_PCB_bank() & 0xff00 ) | ( ( ( portLONG ) ( pxCode ) >> 16 ) & 0xff );      
		pxTopOfStack--;       
	}
	#endif

    /* This is redundant push to the stack. This is required in order to introduce 
    an offset so the task correctly accesses the parameter passed on the task stack. */
    *pxTopOfStack = ( portSTACK_TYPE ) ( pxCode );
    pxTopOfStack--;       

    /* PS - User Mode, ILM=7, RB=0, Interrupts enabled,USP */
    *pxTopOfStack = 0xE0C0;							
	pxTopOfStack--; 

	/* PC */
	*pxTopOfStack = ( portSTACK_TYPE ) ( pxCode );     
    pxTopOfStack--;      
    
    /* DTB | PCB */
	#if configMEMMODEL == portSMALL || configMEMMODEL == portCOMPACT
	{
		*pxTopOfStack = xGet_DTB_PCB_bank();         	
		pxTopOfStack--;
	}
	#endif

	/* DTB | PCB, in case of MEDIUM and LARGE memory models, PCB would be used
	along with PC to indicate the start address of the function. */
	#if( ( configMEMMODEL == portMEDIUM ) || ( configMEMMODEL == portLARGE ) )
	{
		*pxTopOfStack = ( xGet_DTB_PCB_bank() & 0xff00 ) | ( ( ( portLONG ) ( pxCode ) >> 16 ) & 0xff );
		pxTopOfStack--;       
	}
	#endif

	/* DPR | ADB  */
	*pxTopOfStack = xGet_DPR_ADB_bank();				
	pxTopOfStack--;
    
	/* AL */
	*pxTopOfStack = ( portSTACK_TYPE ) 0x9999;		
	pxTopOfStack--;

	/* AH */
	*pxTopOfStack = ( portSTACK_TYPE ) 0xAAAA;		
	pxTopOfStack--;
	
	/* Next the general purpose registers. */
	*pxTopOfStack = ( portSTACK_TYPE ) 0x7777;	/* RW7 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x6666;	/* RW6 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x5555;	/* RW5 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x4444;	/* RW4 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x3333;	/* RW3 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x2222;	/* RW2 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x1111;	/* RW1 */
	pxTopOfStack--;
	*pxTopOfStack = ( portSTACK_TYPE ) 0x8888;	/* RW0 */
		
	return pxTopOfStack;
}
/*-----------------------------------------------------------*/

static void prvSetupRLT0Interrupt( void )
{
/* The peripheral clock divided by 16 is used by the timer. */
const unsigned portSHORT usReloadValue = ( unsigned portSHORT ) ( ( ( configCLKP1_CLOCK_HZ / configTICK_RATE_HZ ) / 16UL ) - 1UL );

	/* set reload value = 34999+1, TICK Interrupt after 10 ms @ 56MHz of CLKP1 */
	TMRLR0 = usReloadValue;    
    
    /* prescaler 1:16, reload, interrupt enable, count enable, trigger */
    TMCSR0 = 0x041B;    
}
/*-----------------------------------------------------------*/

portBASE_TYPE xPortStartScheduler( void )
{
	/* Setup the hardware to generate the tick. */
	prvSetupRLT0Interrupt();
	
	/* Restore the context of the first task that is going to run. */
	portRESTORE_CONTEXT();

	/* Simulate a function call end as generated by the compiler.  We will now
	jump to the start of the task the context of which we have just restored. */	
	__asm(" reti ");


	/* Should not get here. */
	return pdTRUE;
}
/*-----------------------------------------------------------*/

void vPortEndScheduler( void )
{
	/* Not implemented - unlikely to ever be required as there is nothing to
	return to. */
}

/*-----------------------------------------------------------*/

/* 
 * The interrupt service routine used depends on whether the pre-emptive
 * scheduler is being used or not.
 */

#if configUSE_PREEMPTION == 1

	/* 
	 * Tick ISR for preemptive scheduler.  We can use a __nosavereg attribute
	 * as the context is to be saved by the portSAVE_CONTEXT() macro, not the
	 * compiler generated code.  The tick count is incremented after the context 
	 * is saved. 
	 */
	__nosavereg __interrupt void prvRLT0_TICKISR( void )
	{
		/* Disable interrupts so that portSAVE_CONTEXT() is not interrupted */
		__DI();
		
		/* Save the context of the interrupted task. */
		portSAVE_CONTEXT();
		
		/* Enable interrupts */
		__EI();
		
		/* Clear RLT0 interrupt flag */
		TMCSR0_UF = 0;      
		
		/* Increment the tick count then switch to the highest priority task
		that is ready to run. */
		vTaskIncrementTick();
		vTaskSwitchContext();

		/* Disable interrupts so that portRESTORE_CONTEXT() is not interrupted */
		__DI();
		
		/* Restore the context of the new task. */
		portRESTORE_CONTEXT();
		
		/* Enable interrupts */
		__EI();
	}

#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();
	 */
	__interrupt void prvRLT0_TICKISR( void )
	{
		/* Clear RLT0 interrupt flag */
		TMCSR0_UF = 0;  
		
		vTaskIncrementTick();
	}

#endif

/*-----------------------------------------------------------*/

/*
 * Manual context switch. We can use a __nosavereg attribute  as the context 
 * is to be saved by the portSAVE_CONTEXT() macro, not the compiler generated 
 * code.
 */
__nosavereg __interrupt void vPortYield( void )
{
	/* Save the context of the interrupted task. */
	portSAVE_CONTEXT();
	
	/* Switch to the highest priority task that is ready to run. */
	vTaskSwitchContext();
	
	/* Restore the context of the new task. */
	portRESTORE_CONTEXT();
}
/*-----------------------------------------------------------*/

__nosavereg __interrupt void vPortYieldDelayed( void )
{    
    /* Disable interrupts so that portSAVE_CONTEXT() is not interrupted */      
	__DI();
	
	/* Save the context of the interrupted task. */
	portSAVE_CONTEXT();
	
	/* Enable interrupts */
	__EI();
				
	/* Clear delayed interrupt flag */
    __asm (" CLRB  03A4H:0 ");
	
	/* Switch to the highest priority task that is ready to run. */
	vTaskSwitchContext();
	
	/* Disable interrupts so that portSAVE_CONTEXT() is not interrupted */   
	__DI();
	
	/* Restore the context of the new task. */
	portRESTORE_CONTEXT();

	/* Enable interrupts */
	__EI();
}	
/*-----------------------------------------------------------*/