uses dos;

var f, g: file;
m, c, confirm, return: char;
name, out: string;
r: word;
reverse: boolean;

function fe(filename: string): boolean;
var f : file;
begin
  assign(f,filename);
  reset(f,1);
  close(f);
    fe := (ioresult = 0) and (filename <> '');
end;

begin
reverse := false;
name := paramstr(1);
if (name='/?') or (name='?') or (name='-?') then begin
  writeln('USE: tr [source file] [destination file]');
  writeln;
  writeln('Converts a linux/unix text file into a ms-dos text file');
  writeln('adding the ascii #13 value before the ascii #10 value.');
  writeln('Performing the operation twice is perfectly safe because');
  writeln('the program checks if the file is already formatted.');
  halt(0);
end;

case paramcount of
0: begin write('File: '); readln(name); write('Output: '); readln(out); end;
1: begin name:=paramstr(1); write('Output: '); readln(out); end;
2: begin name:= paramstr(1); out:=paramstr(2); end;
3: begin name:= paramstr(1); out:=paramstr(2); reverse := true; end;
end;

if out='' then out:='out.txt';

if not fe(name) then begin
  writeln('File does not exist!'); halt(1); end;
if fe(out) then begin
  if out=name then begin writeln('Overwriting source file not supported yet.'); halt(0); end;
  write('Warning: output file already exists. Overwrite? [Y/N] (y): ');
  readln(confirm);if confirm='' then confirm:='Y';confirm := upcase(confirm);
  if confirm<>'Y' then halt(0);
end;

assign(f, name); reset(f, 1);
assign(g, out); rewrite(g, 1);

return := #13;
m := #42;


while not eof(f) do begin
  blockread(f, c, 1, r);
  if reverse then begin
    if (c<>#13) then blockwrite(g, c, 1, r);
  end else begin
    if (c=#10) and (m<>#13) then blockwrite(g, return, 1, r);
    blockwrite(g, c, 1, r);
    m := c;
  end;
end;

writeln('Done. Formatted file saved in ', out);
end.