/*
   DOS program to set the output voltage of the analog port.
   The output voltage is passed as a parameter on the calling line.

   Syntax:    ANOUT</port> RANGE OUTPUT

   </port>    Optional LPT port number - defaults to LPT1
   RANGE      Voltage range setting of jumper "J1" - 2.5 or 10
   OUTPUT     Output voltage setting - must be less than RANGE

   On exit:   ERRORLEVEL = 0 if all OK
              ERRORLEVEL = 1 if parameter error
*/


#include <stdio.h>
#include <stdlib.h>
#include <dos.h>

#define LPT1   0x00400008  /* BIOS printer address entries */
#define LPT2   0x0040000a
#define LPT3   0x0040000c
#define LPT4   0x0040000e

#define ENABLE 0x02        /* Strobe bit for analog output port */



/*------------------ Program starts here -------------------------------*/


int main(int argc, char *argv[])
  {
    unsigned int port;                    /* LPT port address       */
    float output,                         /* Output voltage         */
          range;                          /* Range setting          */
    unsigned int far *bios_printer_addr;
    unsigned char status,                 /* Status of control port */
                  data;                   /* Hex output data        */
    int lpt_number;                       /* LPT port number        */


    switch(argc)
      {
        case 1:
               printf("Set the output voltage of the analog port.\n\n");
               printf("ANOUT</port> RANGE OUTPUT\n\n");
               printf("</port>    Optional LPT port number - defaults to LPT1.\n");
               printf("RANGE      Voltage range - 2.5 or 10 volts.\n");
               printf("OUTPUT     Output voltage setting - must be less than RANGE.\n\n");
               printf("On exit, ERRORLEVEL = 1 if parameter error.\n");
               exit(1);

        case 2:
        case2:
               puts("No output voltage specified");
               exit(1);

        case 3:
               if (argv[1][0]=='/') goto case2;

               port=*(bios_printer_addr=LPT1);
               if (port==NULL)
                 {
                   puts("LPT1 does not exist");
                   exit(1);
                 }
               sscanf(argv[1],"%f",&range);  /* Get range setting */
               sscanf(argv[2],"%f",&output); /* Get output value  */
               break;

        case 4:
	             if (argv[1][0]=='/') lpt_number=atoi(argv[1]+1);

	             switch(lpt_number)
	               {
	                 case 1 :
	                          port=*(bios_printer_addr=LPT1);
                            if (port==NULL)
                              {
                                puts("LPT1 does not exist");
                                exit(1);
                              }
                            sscanf(argv[2],"%f",&range);
                            sscanf(argv[3],"%f",&output);
	                          break;

	                 case 2 :
	                          port=*(bios_printer_addr=LPT2);
                            if (port==NULL)
                              {
                                puts("LPT2 does not exist");
                                exit(1);
                              }
                            sscanf(argv[2],"%f",&range);
                            sscanf(argv[3],"%f",&output);
	                          break;

                   case 3 :
                            port=*(bios_printer_addr=LPT3);
                            if (port==NULL)
                              {
                                puts("LPT3 does not exist");
                                exit(1);
                              }
                            sscanf(argv[2],"%f",&range);
                            sscanf(argv[3],"%f",&output);
                            break;

                   case 4 :
                            port=*(bios_printer_addr=LPT4);
                            if (port==NULL)
                              {
                                puts("LPT4 does not exist");
                                exit(1);
                              }
                            sscanf(argv[2],"%f",&range);
                            sscanf(argv[3],"%f",&output);
                            break;

	                 default:
                            puts("Invalid printer port");
	                          exit(1);
	               }
      }

      if ((range!=2.5) && (range!=10))
        {
          puts("Invalid range setting");
          exit(1);
        }

      if (output<0)
        {
          puts("Cannot have negative output");
          exit(1);
        }

      if (output>range)
        {
          puts("Output voltage > range");
          exit(1);
        }

    data=(char)(output/range*255);     /* Calculate hex output value */
    status=inportb(port+2);            /* Save control port status   */
    outportb(port,data);               /* Set up hex output          */
    delay(1);
    outportb(port+2,status&~ENABLE);   /* "CE" high                  */
    delay(1);
    outportb(port+2,status|ENABLE);    /* "CE" low                   */
    delay(1);
    outportb(port+2,status&~ENABLE);   /* "CE" high                  */

    return 0;
  }