🚀 go-pugleaf

Take this snippet:

const
  sfile: integer = -1;

procedure open(_file: integer);
begin
{$ifdef fast}
  if _file <> sfile then
    begin;
      sfile:= _file;
{$endif}
      close(datatout);
      assign(datatout, files[_file]);
      settextbuf(datatout, databuf^, 8192);

      if __first_event then
        begin
          rewrite(datatout);
          __first_event:= false;
        end
      else
        append(datatout);
{$ifdef fast}
    end;
{$endif}
end; {open}

It's used a program in which many procedures can write their results to one
of two files (a per event file and a summary file). Going through the
program, I suddenly realized that I had never tracked calls to "open", and
much to my surprise I discovered that on several occasions it's called with
the same value for _file on several consecutive invovations. So I added the
conditionals, and timed again, clean DOS, SMARTDRV with write caching, and
running both the old and the new versions several times in alternating
succession. Much to my surprise the old version, which performs the code
dozens of times more than the the new version, is actually faster! (NB: The
file is initially opened for summary data in the main program)

Does anyone have an explanation?

Thanks,

Robert
--
Robert AH Prins
prinsra@williscorroon.com

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