/*
   DOS program to read the voltage level on one of the A/D inputs.

   Syntax:    ANIN</port> CHANNEL

   </port>    Optional LPT port number - defaults to LPT1
   CHANNEL    Analog input channel number (0 - 13)
              Note: Channels 11-13 are internal test channels.

*/

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

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

#define INIT 0x04          /* Printer port "INIT" signal          */
#define ERROR 0x08         /* Printer port "ERROR" signal         */

#define SELECT 0x08        /* Chip select signal to A/D converter */
#define CLOCK  0x02        /* Clock signal to A/D converter       */
#define ADDR   0x01        /* Address signal to A/D converter     */

#define EOC    0x40        /* End-Of-Conversion mask              */
#define DOUT   0x10        /* Data output mask                    */


/*--------------------- Prototype Declarations --------------------------*/


void send_addr(unsigned int port,unsigned int channel);
int get_data(unsigned int port);


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


int main(int argc, char *argv[])
{
  unsigned int port,                    /* Parallel port address  */
               channel;                 /* A/D channel to read    */

  unsigned int far *bios_printer_addr;

  float data;                           /* A/D data read from channel */
  char status;                          /* Status of control port     */
  int lpt_number;                       /* LPT port number            */



  switch(argc)
    {
      case 1:
             printf("Read & display the voltage level on the specified analog input.\n\n");
             printf("ANIN</port> CHANNEL\n\n");
             printf("</port>    Optional LPT port number - defaults to LPT1.\n");
             printf("CHANNEL    Analog input channel number (0 - 13).\n\n");
             printf("Note: Channels 11-13 are internal test channels.\n\n");
             printf("On exit, ERRORLEVEL = 1 if parameter error.\n\n");
             printf("         ERRORLEVEL = 2 if time out on End-Of-Conversion.\n");
             exit(0);

      case 2:
             if (argv[1][0]=='/')
               {
                 puts("Missing channel number");
                 exit(1);
               }

             port=*(bios_printer_addr=LPT1);
             if (port==NULL)
               {
                 puts("LPT1 does not exist");
                 exit(1);
               }
             sscanf(argv[1],"%d",&channel);
             break;

      case3:
      case 3:
             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],"%d",&channel);
                          break;

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

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

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

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

  if ((channel>13) || (channel<0))
    {
      puts("Invalid channel number");
      exit(1);
    }


  status=inportb(port+2);            /* Save control port status     */
  outportb(port+2,status&~SELECT);   /* "CS" high                    */
  delay(1);
  outportb(port,~CLOCK);             /* "CLK" low                    */
  delay(1);


  send_addr(port,channel);           /* Select A/D converter,
                                        Clock in 4-bit address,
                                        Issue 6 more clocks cycles
                                        Deselect A/D converter       */

  while (!(inportb(port+1)&EOC));    /* Wait for EOC high            */

  data=(float)get_data(port)/1024*5; /* Read data from A/D converter
                                        and convert into decimal     */

  printf("Analog channel %d = %4.3fV\n",channel,data);

  outportb(port+2,status);           /* Restore control port status  */


  return 0;
}


/*------------------------------------------------------------------------*/

/* Send channel address to A/D converter chip
   Also send remaining 6 clock cycles         */

void send_addr(unsigned int port, unsigned int channel)
{
  int x;
  char status;

  status=inportb(port+2);             /* Save control port status         */
  outportb(port+2,status|SELECT);     /* Select A/D chip ("CS" low)       */

  for (x=0; x<11; x++)                /* Clock in address + 6 more clocks */
    {
      delay(1);
      if (channel&0x0008)             /* Is address bit high?             */
        {
          outportb(port,ADDR);        /* Yes, set "ADDR" pin high         */
          outportb(port,ADDR|CLOCK);  /* "CLK" high                       */
          delay(1);
          outportb(port,ADDR);        /* "CLK" low                        */
        }
      else
        {
          outportb(port,CLOCK&ADDR);  /* No, set "ADDR" pin low           */
          outportb(port,CLOCK);       /* "CLK" high                       */
          delay(1);
          outportb(port,CLOCK&ADDR);  /* "CLK" low                        */
        }

      channel=channel<<1;             /* Shift in next address bit        */
    }

  outportb(port+2,status&~SELECT);    /* "CS" high                        */
  delay(1);
}


/*------------------------------------------------------------------------*/


/* Get serial data from A/D converter chip and return it */

int get_data(unsigned int port)
{
  int data=0,                         /* Holds data read           */
      x;
  char status;

  status=inportb(port+2);             /* Save control port status  */
  outportb(port+2,status|SELECT);     /* Select A/D chip ("CS" low */

  for (x=0; x<10; x++)                /* Clock out 10 data bits    */
    {
      delay(1);
      data=data<<1;                   /* Shift bits along          */

      if (inportb(port+1)&DOUT)       /* Is data bit high?         */
        data=data|0x0001;             /* Yes, "data" bit = 1       */
      else
        data=data&0xfffe;             /* No, "data" bit = 0        */

      outportb(port,CLOCK);           /* "CLK" high                */
      delay(1);
      outportb(port,~CLOCK);          /* "CLK" low                 */
    }

  outportb(port+2,status&~SELECT);    /* "CS" high                 */
  return(data);
}