/**************************************************/
/*  Software control function generator           */
/*  Using the printer port                        */
/*  Single square wave pulse on ext trigger       */
/*  Frequency depends on the loop value entered   */
/**************************************************/

#include<stdio.h>
#include<conio.h>
#include<dos.h>
#include<math.h>
#include<time.h>

unsigned char    trigg, inval, top, topcnt, printcontrol ;

int              loop, base, angle ;
float            maxv, minv ;

/***********************************************/
/*       Reads the input data                  */
/***********************************************/

unsigned char readport()
{
 unsigned char dummy ;

 dummy = inp(base + 2) ;
 outp((base + 2), (dummy & 0X0D)) ;
 inval = (inp(base + 1) & 0XF0) >> 4 ;
 outp((base + 2), (dummy | 0X02)) ;
 inval = (inval | inp(base + 1) & 0XF0) ^ 0X88 ;
 return inval ;
}


/*************************************************/
/*  output the high voltage                      */
/*************************************************/

void set_high()
{
 unsigned int  cnt, cntmax, bincode ;
 unsigned char pol, inprt ;
 int           int_vout ;
 float         vout, hvout ;
 time_t t, end_t ;

 if (maxv >= 0 )
   {
    pol = 1 ;
    hvout = maxv ;
   }
  else
   {
     pol = 0 ;
     hvout = maxv * -1 ;
   }

 vout = 511.0 * (hvout / 5.0) ;
 int_vout = vout ;
 if (pol == 1) bincode = int_vout + 0X0200 ;
  else         bincode = 0X0200 - int_vout ;

 printf("Setting high Voltage level: Vout  %8.2f\n", maxv) ;

 cntmax = bincode & 0X3FF ;



 cnt = cntmax ;

 inprt = cnt ;
 topcnt = cnt >> 8 ;
 topcnt = topcnt & 0X03 ;

 if (topcnt == 0X00) top = (top & 0X02) | 0X01 ;

 if (topcnt == 0X01) top = top & 0X02 ;

 if (topcnt == 0X02) top = top | 0X05 ;

 if (topcnt == 0X03) top = (top & 0X02) | 0X04 ;

 outp(base, inprt) ;
 outp(base + 2, top) ;
 t = time(NULL) ;
 end_t = t + loop ;
 while(t < end_t)
  {
   t = time(NULL) ;
  }

 /* delay(loop) ; */
}

/*************************************************/
/*  output the low voltage                       */
/*************************************************/

void set_low()
{
 unsigned int  cnt, cntmin, bincode ;
 unsigned char pol, inprt ;
 int           int_vout ;
 float         vout, lvout ;



 if (minv >= 0 )
   {
    pol = 1 ;
    lvout = minv ;
   }
  else
   {
     pol = 0 ;
     lvout = minv * -1 ;
   }

 vout = 511.0 * (lvout / 5.0) ;
 int_vout = vout ;
 if (pol == 1) bincode = int_vout + 0X0200 ;
  else         bincode = 0X0200 - int_vout ;

 printf("Setting low voltage level: Vout   %8.2f\n",minv) ;

 cntmin = bincode & 0X3FF ;

 cnt = cntmin ;


 inprt = cnt ;
 topcnt = cnt >> 8 ;
 topcnt = topcnt & 0X03 ;

 if (topcnt == 0X00) top = (top & 0X02) | 0X01 ;

 if (topcnt == 0X01) top = top & 0X02 ;

 if (topcnt == 0X02) top = top | 0X05 ;

 if (topcnt == 0X03) top = (top & 0X02) | 0X04 ;

 outp(base, inprt) ;
 outp(base + 2, top) ;

}


/**********************************************************/
/* Wait for high level and then return if signal goes low */
/**********************************************************/

void low_trig()
{
 printf("Wait for signal to go high\n") ;

 while ((readport() & 0X01) != 0X01) ;

 printf("Waiting for low trigger \n") ;

 while ((readport() & 0X01) != 0X00) ;
}


/**********************************************************/
/* Wait for low level and then return if signal goes high */
/**********************************************************/

void hi_trig()
{
 printf("Wait for signal to go low\n") ;

 while ((readport() & 0X01) != 0X00) ;

 printf("Waiting for high trigger\n") ;

 while ((readport() & 0X01) != 0X01) ;
 }



/*****************************************************/
/*              Main Program                         */
/*****************************************************/

int main(void)
 {
   int LPT1 = 0X378 ;
   int LPT2 = 0X278 ;
   int LPT3 = 0X3BC ;

   int dummy ;

   clrscr() ;

   base   = LPT2 ;
   top    = 0 ;
   printf ("SINGLE PULSE GENERATOR\n\n") ;

   printf ("Enter Pulse width in seconds ") ;
   scanf("%d", &loop) ;
   fflush(stdin) ;

   printf ("Enter max Voltage ") ;
   scanf("%f", &maxv) ;
   fflush(stdin) ;

   printf ("Enter min Voltage ") ;
   scanf("%f", &minv) ;
   fflush(stdin) ;

   printf ("Enter trigger level (0 or 1) ") ;
   scanf("%d", &trigg) ;
   fflush(stdin) ;

   set_low() ;

   if (trigg == 1)
     {
      printf("Triggering on logic 1 pulse \n\n") ;
      hi_trig() ;
     }
    else
     {
       printf("Triggering on logic 0 pulse\n\n") ;
       low_trig() ;
     }

   set_high() ;
   set_low() ;
   return 0 ;
 }