ISO Pascal reference manual

Chapter 6
TYPE
IntRef =tInteger;
FNCParams = RECORD p1, p2: IntRef END;
VAR
FNCParamBlock: FNCParams;
IMPORT FUNCTION FNC (VAR p: FNCParams): IntRef;
PROCEDURE LocalFNC (n1, n2: Integer): Integer;
VAR
rp: IntRef;
BEGIN
WITH FNCParamBlock DO BEGIN pit := a; p21:= b; END;
rp := FNC (FNCParamBlock);
LocalFNC = rpi;
END;
BEGIN
WITH FNCParamBlock DO BEGIN NEW (p1); NEW (p2) END;
WITH FNCParamBlock DO BEGIN DISPOSE (p1); DISPOSE (p2) END;
END.
In this version, the total cost of an individual call on LocalFNC has been
reduced to a modest level, but at some cost in terms of program clarity.
However the program does remain within the bounds of what is nominally
`legal' Pascal (ignoring the IMPORT mechanism itself). An alternative, but
less 'clean' method is to use an extension of the Pascal compiler which
permits the calculation of the run-time address of a variable, as below:
TYPE
IntRef =iInteger;
FNCParams = RECORD p1, p2: Integer END;
IMPORT FUNCTION FNC (VAR p: FNCParams): IntRef;
FUNCTION LocalFNC (a, b: Integer): Integer;
VAR rp: IntRef;
paramBlock: FNCParams;
BEGIN
paramBlock.p1 := ADDRESS (a);
paramBlock.p2 := ADDRESS (b);
44 Pascal Issue