/*****************************************************************************
* This code installs and uses a trigger handler.  It prompts the user for a  *
* trigger line to watch, and a protocol to watch for, and then waits until   *
* the desired trigger is seen.                                               *
*****************************************************************************/

#include <utility.h>
#include <ansi_c.h>
#include <nivxi.h>
#include <userint.h>

static char ch;
static UINT16 lines_enabled;
static INT16 controller;
static unsigned short line_triggered;
static NIVXI_HTRIG *new_trig_handler;
static NIVXI_STATUS Status;
static int disarm, line, protocol, trigevent, protocol_to_watch, trig_to_watch;

/****************************************************************************
* This is the installed trigger handler.  Once installed using the VXI      *
* function "SetVXItrigHandler()", anytime the proper trigger is seen (line  *
* and protocol), the code in this function will be executed.  In this case, *
* all that is needed is to save information to global variables so the data *
* can be used in later code.  Do not attempt to do UIR or STDIO output from *
* within the trigger handler.                                               *
****************************************************************************/

NIVXI_HQUAL void NIVXI_HSPEC mytrighandler (INT16 ctrlr,
											UINT16 ln,
											UINT16 type)
{
	line_triggered = ln;	  //save value to global variable
	trigevent = 1;            //set the event flag
}

/******************************************************************************
* In the main code, the flow is as follows:									  *
*																			  *
* 1) InitVXIlibrary(): initialize the VXI library.							  *
* 2) prompt the user for data concerning what to watch for.					  *
* 3) EnableTrigSense(): allows the CPU to "see" triggers.					  *
* 4) SetTrigHandler(): installs trigger handler shown above this comment block*
* 5) wait in a while loop for the trigger to occur.                           *
* 6) display results for user.                                                *
******************************************************************************/

void main ()
{
	Cls();					//clear the STDIO widow
	
	if ( InitVXIlibrary() )	//This function must be called to use VXI functions.
	{
		printf ("Unable to Initialize VXI library... exiting");
		exit (0);
	}
	
   /*
    * Prompt the user for info regarding trigger line and protocol
    */
    printf ("What trigger line would you like to watch? (0-7) >> ");
    scanf ("%d", &line);
    printf ("What protocol would you like to watch for?  (options below)\n");
    printf ("2 - Start\n3 - Stop\n4 - Sync\n5 - Semi-sync\n6 - Async\n>> ");
    scanf ("%d", &protocol);
    
   /*
    * First we must enable the CPU to see a trigger.  To do this, we need to
    * use the following function and parameters:
    *
    * controller: which controller to enable sensing
    * line: trigger line to watch
    * protocol: protocol to watch for
    */
    controller = -1;  //use default controller
    //line and protocol values from above
    Status = EnableTrigSense(controller, line, protocol);
	
   /* 
    * To watch for a trigger we must install our own trigger handler.
    * The parameters of the function to do that are:
    *
    * lines_enabled: contains a bit vector of trigger lines
    * new_trig_handler: contains a pointer to the new trigger handler
	*/
	lines_enabled = 0xFF;	    //watch all trigger lines
	new_trig_handler = mytrighandler;
	Status = SetTrigHandler (lines_enabled, new_trig_handler);
		if ( Status )
		{
			printf ("Error installing trigger handler... exiting");
			exit (0);   //could not install handler, need to exit code
		}
	printf ("\nWatching for trigger to occur...\n");
	
	trigevent == 0;     //clear trigger event flag
	
	while ( trigevent == 0 )   
		{
		}	//stay in this loop until a trigger is detected.
		
	//since we have fallen out of the while loop, a trigger was detected
	printf ("\n\nI was triggered using the desired protocol on line %d\n",line_triggered);
	printf ("\n<Press Enter to quit>");
	getchar();
	scanf ("%c", &ch);    //wait for user to hit a key to quit
	
	CloseVXIlibrary();
}