program t73_varparam;

{ t73 -- VAR parameters, and a parameter shadowing a global of the same name.

  CALC.INC has

      Ch : Char;                                  (* a GLOBAL *)
      procedure IBMCh(var Ch: Char); ... Ch := ^E ... end;
      IBMCh(Ch);

  and expects the caller's Ch to change.  This fixture is that shape:
  IBMCh's parameter is also named Ch, which ISO Pascal allows (the inner
  declaration shadows the outer one); DupTest used to reject it outright.

  Five calls, so every address path is exercised:
    * a global CHAR by reference (one byte through the pointer),
    * a global INTEGER by reference (two bytes through the pointer),
    * a LOCAL CHAR by reference (the caller passes LEA BP+off),
    * a VAR parameter passed ON to another VAR parameter (Relay -> IBMCh),
    * READ into a VAR parameter (ReadIt), which must store through the
      pointer, not into the parameter slot.

  A by-value implementation would print H, H, 41 and a; the .out is
  h, h, 42, ? and the character read by ReadIt. }

var
   Ch : char;
   i  : integer;

procedure IBMCh (var Ch : Char);
begin
   if Ch = 'H' then
      Ch := 'h'
   else
      Ch := '?'
end;

procedure Bump (var n : integer);
begin
   n := n + 1
end;

procedure Relay (var c : char);
begin
   IBMCh (c)
end;

procedure ReadIt (var c : char);
begin
   read (c)
end;

procedure Local;
var
   v : char;
begin
   v := 'a';
   IBMCh (v);
   writeln (v)
end;

begin
   Ch := 'H';
   IBMCh (Ch);
   writeln (Ch);
   Ch := 'H';
   Relay (Ch);
   writeln (Ch);
   i := 41;
   Bump (i);
   writeln (i);
   Local;
   ReadIt (Ch);
   writeln (Ch)
end.