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program ChCount(input,output);

(* ChCount counts character frequencies in a file,
   and prints the result in a tabular format.

   to use, do		(PDP8 Pascal)

	.R P,CHCNT,infile,outfile


*)(*$L-*)

const
  lowch =	' '	(* ASCII *);
(*lowch =	'a';	(* U of M (CDC) NOS *)
  highch =	'~'	(* ASCII *);
(*highch =	';';	(* U of M (CDC) NOS *)
  ncolumns =	4	(* columns wide for report *);

var
  counter : array[lowch..highch] of integer;
  ch :		char	(* working char var *);
  row : 	integer (* current row *);
  count :	integer (* count to print out *);
  column :	1..ncolumns (* current column *);
  numrows :	integer (* number of rows to print *);
  tablecells :	integer (* cells in rectangular portion *);
  charsetsize:	integer (* number of chars in set *);
  firstprintingchar: integer (* ASCII first printing character *);
  charordinal : integer (* ord of current char *);
  inputlines :	integer (* input line counter *);
  charcount :	integer (* count of characters read *);
  linewidth :	integer (* width of current line *);
  maxlinewidth : integer(* longest line in input *);

begin
  charsetsize := ord(highch) - ord(lowch) +1;
  firstprintingchar := ord(lowch);
  inputlines := 0;
  charcount := 0;
  maxlinewidth := 0;
  writeln(output);
  writeln(output,'   character frequency counter.');
  writeln(output);
  for ch := lowch to highch do counter[ch] := 0;

  (* scan file *)
  while not eof(input) do
    begin
      linewidth := 0;
      inputlines := inputlines + 1;
      while not eoln(input) do
	begin
	  counter[input^] := counter[input^] + 1;
	  linewidth := linewidth + 1;
	  charcount := charcount + 1;
	  get(input)
	end;
      if linewidth > maxlinewidth then maxlinewidth := linewidth;
      readln(input)
    end;

  writeln(output);
  writeln(output,'   input character count = ', charcount : 6);
  writeln(output,'   input line count =      ', inputlines : 6);
  writeln(output,'   longest line length =   ', maxlinewidth : 6);
  writeln(output);
  if charcount > 0 then (* produce frequency table *)
    begin
      writeln(output);
      write(output,' ' : 3);
      for column := 1 to ncolumns do
	begin
	  write(output,' count	ord ch');
	  if column < ncolumns then write(output,' ' : 4)
	end;
      writeln(output);
      writeln(output);
      numrows := charsetsize div ncolumns (* if rectangular shape *);
      tablecells := numrows * ncolumns (* for nonrectangular table *);
      if tablecells < charsetsize then numrows := numrows + 1;

      (* write out columnar table *)
      for row := 1 to numrows do
	begin (* write each row as a line *)
	  write(output,' ' : 3); (* new line *)
	  charordinal := row + firstprintingchar - 1;
	  for column := 1 to ncolumns do
	    begin
	      if charordinal <= ord(highch) then
		begin
		  count := counter[chr(charordinal)];
		  if count = 0
		    then write(output, ' ' : 6)
		    else write(output, count : 6 );
		  write(output,' ' : 2, (charordinal) : 3,
			' ' : 2, chr(charordinal));
		  if column < ncolumns then write(output, ' ' : 4);
		  charordinal := charordinal + numrows
		end
	    end;
	  writeln(output)
	end;
      writeln(output) (* final blank line *)
    end
end (* ChCount *).