program counter(input, output);
(* counter: program counter

  Dr. Thomas D. Schneider
  National Institutes of Health
  National Cancer Institute
  Center for Cancer Research Nanobiology Program
  Molecular Information Theory Group
  Frederick, Maryland  21702-1201
  toms@ncifcrf.gov
  permanent email: toms@alum.mit.edu (use only if first address fails)
  http://www.ccrnp.ncifcrf.gov/~toms/

 *)

label 1; (* end of program *)

const
(* begin module version *)
   version = 1.00; (* of counter.p 2009 Apr 13
2009 Apr 13, 1.00: origin
*)
updateversion = 1.00; (* defines lowest acceptable current parameter file *)
(* end module version *)

(* begin module describe.counter *)
(*
name
   counter: program counter

synopsis
   counter(input: in, output: out)

files

   input:  parameters to control the program.  The file must contain the
      following parameters, on one line:

      number: an integer number to display
      width:  the number of positions to use for the display

   output: messages to the user

description

   Output the given number and then backspace.
   This allows a running counter to be displayed by a script.

examples

Example script:

********************************************************************************
#!/bin/tcsh -f
#(ie run the tshell on this but don't read the .cshrc or .tcshrc)

echo version = 1.00 of mk 2009 Apr 13
# 2009 Apr 13, 1.00: origin 

@ n = 0
echo -n "here we go! >"
while ($n < 1000)
  echo "$n 5" | counter
  @ n = $n + 1
end
echo "$n< done!"
********************************************************************************

documentation

see also

   {module digitcounter in} scan.p

author

   Thomas Dana Schneider

bugs

technical notes

*)
(* end module describe.counter *)

var
   afile, (* file used by this program *)
   counterp, (* file used by this program *)
   bfile: text; (* file used by this program *)

(* begin module halt *)
procedure halt;
(* stop the program.  the procedure performs a goto to the end of the
   program.  you must have a label:
      label 1;
   declared, and also the end of the program must have this label:
      1: end.
   examples are in the module libraries.
   this is the only goto in the delila system. *)
begin
      writeln(output,' program halt.');
      goto 1
end;
(* end module halt version = 'delmod 6.16 84 mar 12 tds/gds'; *)

(* begin module digitcounter *)
procedure digitcounter(var afile: text; var counter, previous: integer);
(* Make a digit counter on a single line.  The digits are written and
overwritten the next time by using control H.  To initialize, set the
'previous' variable to zero.  To terminate, put a
"writeln(afile,'whateveryouwant');".  If you put
"write(afile,'babble-counter: ');" before the call, the numbers will
show up on the same line and your message can indicate what the
counter is about. *)

const
   ordControlH = 8; (* the ordinal of control H so that we do not
      have to put an actual control H into the source code.
      The chr() of this will give the control H character *)

var
   digits: integer; (* number of digits in in previous number *)
   digitcount: integer; (* index to digits *)
begin
   if previous > 0 then begin
      (* backspace the PREVIOUS number of digits *)
      (* Compute the number of digits.  For sequencenumber = 1000, we
      add an extra 0.5 to avoid rounding that would give 3 instead of
      4 as the number of digits.  Other cases work fine with this. *)
      digits :=  trunc(ln(previous+0.5)/ln(10)+1);
{
writeln(output, digits:1, ' ', counter:1);
      for digitcount := 1 to previous do write(output, 'H');
}
      for digitcount := 1 to digits do write(output, chr(ordControlH));
{
writeln(output, digits:1, ' ', counter:1, ' ',previous:1);
}
   end;
   write(output, counter:1);
   previous := counter;
end;
(* end module digitcounter version = 5.32; (@ of prgmod.p 2007 Mar 25 *)

(* begin module counter.themain *)
procedure themain(var afile, counterp, bfile: text);
(* the main procedure of the program *)

const
   ordControlH = 8; (* the ordinal of control H so that we do not
      have to put an actual control H into the source code.
      The chr() of this will give the control H character *)

var
   parameterversion: real; (* parameter version number *)
   widthindex: integer; (* index for the width *)
   number: integer; (* the number to display *)
   width: integer; (* the number of characters used for the number *)
{
   previous: integer; (* the number of characters used for the number *)
}
begin

   read(input, number, width);
   write(output, number: width);
   for widthindex := 1 to width do begin
       write(output, chr(ordControlH));
   end;

{
   previous := 0;
   digitcounter(output,number, previous)
}

end;
(* end module counter.themain *)

begin
   themain(afile, counterp, bfile);
1: end.