/*************************************
          C O U N T D O W N
          by  Ian C. Sharpe
     (c) Personal Computing 1990

Use: COUNTDN c r

c=counter number 0-99
r=value to reset when run down 0-255

If countdown=0 then ERRORLEVEL=1
               else ERRORLEVEL=0

ERRORLEVEL=-1 if error occurs

Compiled with Zortech C v3:
     ztc countdn -a -w -msi -o
Refer to magazine text for other compilers

Creates hidden data file \COUNTDAT.###
*************************************/

#define MAXCOUNTERS 100

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

int checkisnum(char *);
void hidefile(char *);

main(int argc, char *argv[])
{
int counter,resetval,i,c,blastoff;
char counters[MAXCOUNTERS];
FILE *fp;

   puts("\nCOUNTDOWN  (c) March 1990 Ian Sharpe\n");

   /*
      Obtain parameters & check their validity
   */
   
   if(argc != 3)
      {
      puts("Wrong parameter count");
      puts("Use COUNTDN [counter] [reset val]");
      exit(-1);
      }

   if( checkisnum(argv[1])==0 || checkisnum(argv[2])==0 )
      {
      printf("%s %s is not a valid command line\n",argv[1], argv[2]);
      exit(-1);
      }

   if( (counter=atoi(argv[1])) >= MAXCOUNTERS || counter < 0 )
      {
      printf("Counter number must be 0-%d. You put %d\n",MAXCOUNTERS-1, counter);
      exit(-1);
      }

   if( (resetval=atoi(argv[2])) > 255 || resetval<0 )
      {
      printf("Reset values must be 0-255. You put %d\n",resetval);
      exit(-1);
      }

   /*
       Try to find data file.
       If not found, create it if the user permits
   */

   if( ! findfirst("\\COUNTDAT.###", 0x02 ) )
      {
      puts("Can't find count down data");
      puts("file \\COUNTDAT.### in root");
      puts("directory of default drive");
      puts("\nCreate it? (Y/N)");
      for(c=0; c != 'Y' && c != 'N'; )
         c=toupper(getch());
      if( c == 'N' )
         {
         puts("Aborting");
         exit(-1);
         }
   
      fp=fopen("\\COUNTDAT.###", "wb");
      memset(counters, 0, MAXCOUNTERS);
      if( ! fwrite(counters, MAXCOUNTERS, 1, fp) )
         {
         puts("Error creating \\COUNTDAT.###\nAborting");
         fclose(fp);
         unlink("\\COUNTDAT.###");
         exit(-1);
         }
      fclose(fp);
      hidefile("\\COUNTDAT.###");
      }

   /*
      Open data file, decrement counter, rewrite data
   */

   fp=fopen("\\COUNTDAT.###","r+");
   if( ! fread(counters, MAXCOUNTERS, 1, fp) )
      {
      puts("Can't read from \\COUNTDAT.###\nAborting");
      fclose(fp);
      exit(-1);
      }

   if( counters[counter] == 0 )
      {
      putchar(7);
      counters[counter]=(char)resetval;
      blastoff=1;
      }
   else
      {
      counters[counter]--;
      blastoff=0;
      }

   rewind(fp);
   fwrite(counters, MAXCOUNTERS, 1, fp);
   fclose(fp);
   exit(blastoff);
}


int checkisnum( char *string ) 
/*
  Checks if every character in *string is a digit 0...9
  If not, return 0. If OK, return 1
*/
{
   while( *string )
      if( ! isdigit(*string++) )
         return 0;
   return 1;
}


void hidefile(char *filename)
/*
   Hide file
*/
{
union REGS regs;

   regs.h.ah=0x43;
   regs.h.al=1;
   regs.x.cx=2; /* 2=hidden attribute */
   regs.x.dx=(int)filename;
   intdos(&regs, &regs);
}