/****************************************************************************
 *                        C SAMPLE #1: SAMPLE1.C                            *
 *                                                                          *
 *  This sample will prompt the user for a voltage between 0 and 10 volts,  *
 *  then calculate the actual voltage based on the resulution of the DAC and*
 *  output the voltage to the desired DAC channel.                          *
 *                                                                          *
 *  The following setup of the board is expected:                           *
 *      -- Reference voltage for the DACs should be -10V.                   *
 *                                                                          *
 ****************************************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <sys/io.h>

unsigned AskForBaseAddress(unsigned int OldOne)
{
	char msg[3];
	unsigned int newone;
        unsigned int temp = 0;
        int index = 0;        
	int letter;

	puts("Please enter the Base Address for your card (in hex)");
 	printf("or press ENTER for %X.\n>", OldOne); 
        while(temp==0)
        {  
          newone=0;
          index=0; 
          while((letter = getchar())!='\n') //Read char by char and store in Msg
          msg[index++] = letter;
          sscanf(msg, "%X", &newone);
          if(newone==0){ //Check to see if address was inputed
            temp=OldOne;  //Assign default if not
 	  } else if((newone>=0x100)&&(newone<=0x3f0)){ //Check to see if inputed addres is valid
	    temp=newone; 
          } else { //If Newone invalid ask for new value.
             printf("\nEnter the Base Address or press ENTER for %x > ", OldOne);
             for(index=0; index<=3; index++)
              msg[index]=0;
	  } //Run while until temp = valid address
        } 
        return(temp);
} /* end of AskForBaseAddress */

void IOPermission(unsigned abase) {
  if(ioperm(abase,16,1)<0)
  {
     fprintf(stderr, "NO IO PERMISSION\n");
  }
}

/****************************************************************************
 *  FUNCTION: write_DAC() - local routine                                   *
 *                                                                          *
 *   PURPOSE: Prompts the user for DAC number and voltage, then calculates  *
 *            the actual output voltage based on resolution, displays it    *
 *            and writes the value to the DAC.                              *
 ****************************************************************************/
void write_DAC(unsigned int Address)
{
   float           volt_value_entered,volt_value_expected;
   unsigned        counts_entered,temp,dac_number;
   unsigned char   lo_byte,hi_byte;
   int           ch,clear;

   /* prompt for the DAC number and desire voltage. */
   while((clear=getchar()) != '\n'); 
   system("clear");
   do {   
       printf("Enter the DAC number you wish to output to (0 or 1 only): ");
       ch=getchar();
      dac_number=ch-'0';         /* using ascii code to get dac_number */
   } while (((int)dac_number < 0) || ((int)dac_number > 1));
   do {
   printf("\nEnter a voltage between 0.000v to 9.997v: ");
   scanf("%f",&volt_value_entered);
   } while ((volt_value_entered<0.000) || (volt_value_entered>9.997));
   volt_value_entered /= 0.002441;
  
   /* compute the digital output needed for this value and the actual voltage
      that will be expected, and display the voltage. */
   
   counts_entered=(int) volt_value_entered;
   volt_value_expected = (float) counts_entered * 0.002441;
   puts("\n\n\nDue to the 12-bit resolution of the DAC, you should expect");
   printf("to see a voltage of %4.3f.\n",volt_value_expected);

   /* prepare the control word and write to the DAC */
   temp = counts_entered;
   counts_entered /= 256;                       /* extract hi byte        */
   hi_byte = (unsigned char) counts_entered;    /* convert to character   */
   temp %= 256;                                 /* extract low byte       */
   lo_byte = (unsigned char) temp;              /* convert to character   */
   outb(lo_byte,Address+0x08+(2 * dac_number)); /* write low byte         */
   outb(hi_byte,Address+0x08+(2*dac_number+1)); /* write high byte        */
} /* end write_DAC */

/****************************************************************************
 *                                                                          *
 *  FUNCTION: main() - local routine                                        *
 *                                                                          *
 ****************************************************************************/
int main()
{
   unsigned int Address;
   int key,clear;
  
   system("clear");
   printf(
    "                        C SAMPLE #1: SAMPLE1.C                            \n"
    "                                                                          \n"
    "  This sample will prompt the user for a voltage between 0 and 10 volts,  \n"
    "  then calculate the actual voltage based on the resolution of the DAC and\n"
    "  output the voltage to the desired DAC channel.                          \n"
    "                                                                          \n");
   Address=AskForBaseAddress(0x340);
   IOPermission(Address);
   system("clear");
   outb(0,Address+0x08);    /* set DAC to 0 output */
   outb(0,Address+0x09);
   outb(0,Address+0x0a);    /* set DAC to 0 output */
   outb(0,Address+0x0b);
   printf(
    "\n\n\n  Board Configuration:                     \n\n"
    "  -- Base address is %x hex.                       \n"
    "  -- DACs must be placed in the 10V unipolar mode. \n"
    "  -- The 2's complement jumper must be removed.    \n"
    "\n\n\n\nPress any key to continue", Address);
   do {
      write_DAC(Address);
      while((clear=getchar()) != '\n');
      puts("\nWould you like to output another value (Y or N)");
      key=toupper(getchar());
   } while(key != 'N');
   return 0;
} /* end main */