ISO Pascal reference manual

END;
LocaIFNC = rip.; Idereference for F77 result)
Using Pascal with other languages
(N.B. As described in section 6.2.2 it is necessary to compile this code with
assignment checks disabled, otherwise the reference to the Fortran result
variable via a Pascal pointer will probably fail since the result variable will
not have been allocated on the Pascal heap.)
This is the obvious logical method of interfacing the procedure, but is by no
means the most efficient way of calling a Fortran function! The main
problem is that the only (legal) way of using pointers in standard Pascal is
in claiming, accessing and disposing of heap memory via NEW, DISPOSE
etc. - it is not possible to point pointers at normal local variables. In the
above example some improvement would obtain by specifying FNC as
taking a VAR parameter of type FNCParams, rather than a pointer to such
a structure - VAR parameters are implemented by the same mechanism in
low-level terms. Thus:
IMPORT FUNCTION FNC (VAR p: FNCParams): IntRef;
PROCEDURE LocaIFNC (n1, n2: Integer): Integer;
VAR
rp: IntRef;
paramBlock: FNCParams;
BEGIN
WITH paramBlock DO BEGIN
NEW (p1); NEW (p2);
p1l := n1; p21 := n2;
rp := FNC (paramBlock);
DISPOSE (p1); DISPOSE (p2)
END;
LocalFNC = rpt;
END;
If the function is to be called more than once, it might be worthwhile
removing the calls on NEW and DISPOSE from the procedure, since these
involve an amount of heap management activity. This could be done by
making the parameter block a global variable, and claiming the space for
the parameters (via p1 and p2) only once, before the first call on LocalFNC
was made. Thus we would arrive at:
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