irq.c

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/*******************************************************************************
 * 
 * ARM Strategic Support Group
 *
 *******************************************************************************/

/*******************************************************************************
 *
 * Module       : irq.c
 * Description  : Installs an IRQ handler and initializes the timer and button
 *				  interrupts on the Samsung KS32C50100
 * Tool Chain	: ARM Developer Suite v1.0
 * Platform     : Evaluator7T
 * History      : 
 *
 *				980416 Andrew N. Sloss
 *              - added button interrupt service
 *              - added header information
 *
 *		  		990930 Andrew N. Sloss
 *		  		- abstracted the timer and button handling routines 
 *
 *				2000-04-3 Andrew N. Sloss
 *				- Ported to Evaluator7T
 * 
 * Notes        : none...
 *
 *******************************************************************************/

/*******************************************************************************
 * IMPORT
 *******************************************************************************/

#include "led.h"
#include "button.h"
#include "timer.h"
#include "macros.h"

/*******************************************************************************
 * MACRO'S
 *******************************************************************************/

// none...

/*****************************************************************************
 * EXTERN's
 *****************************************************************************/

extern void handler_irq(void);
extern void SetupSVC(void);
extern int  Angel_IRQ_Address;

/*****************************************************************************
 * GLOBALS
 *****************************************************************************/

/*****************************************************************************
 * ROUTINES
 *****************************************************************************/

/* -- irq_installhandler ------------------------------------------------------
 *                                                            
 * Description  : Places a branch instruction for the routine into the defined 
 *                'vector' location - this function returns the original 
 *                contents of the 'vector      
 *
 * Parameters   : unsigned routine - IRQ handler
 *				: unsigned *vector - IRQ vector   
 * Return       : 
 * Notes        : 'routine' MUST BE WITHIN A  RANGE OF 32Mbytes FROM 'vector'
 *                                                                             
 */

static void irq_installhandler (unsigned routine, unsigned *vector) 
{
unsigned old_vector_value = 0;
unsigned *absolute;   
  
   old_vector_value = 0;

	/************************************************************************	
	 * Now the inverse must be done on the original vector to retrieve the  * 
	 * Angel IRQ Handler routine .                                          *
	 ************************************************************************/
   
   old_vector_value  = *vector;  	 // Get old vector contents ....................
   old_vector_value ^= 0xe59ff000;	 // Mask off the instruction to get the offset
 
	// ** calculate absolute address

   absolute	     	= (unsigned *) (0x18 + old_vector_value+0x8); 
					// IRQ Address
   Angel_IRQ_Address 	= *absolute; 	// chain Angel Interrupt Handler	  
   *absolute		= routine; 	// IRQ handler

}

/* -- irq_init ----------------------------------------------------------------
 * 
 * Description  : Initializes all the IRQ interrupt and installs an IRQ handler.
 *
 * Parameters   : none...
 * Return       : none...
 * Notes        : none...
 *
 */

void irq_init (void)
{

	/*  This is necessary if Angel is not running
	 *  on the target (as when running semi-hosted
	 *  from Multi-ICE) otherwise, let Angel handle 
	 *	it */

	SetupSVC();	

	// 
	// initializes button and timer
	// 
	
	timer_init 	();
	button_init ();

	// 
	// install handler
	// 

	irq_installhandler ((unsigned)handler_irq, (unsigned *)IRQVector);
}

/*******************************************************************************
 * END OF irq.c
 *******************************************************************************/