Variable forcing now uses limited list and buffer instead of systematical instance tree traversal and in-tree "fvalue" to keep track of forced value for pointed variables (external, located). Pointer swapping is performed when forcing externals and located, with backup being restored when forcing is reset. Match Beremiz commit 93ad018fb602.
FUNCTION_BLOCK DIFFEQ
VAR_INPUT
RUN : BOOL ; (* 1 = run, 0 = reset *)
XIN : REAL ;
A : ARRAY[1..] OF REAL ; (* Input coefficients *)
M : INT ; (* Length of input history *)
B : ARRAY[0..] OF REAL ; (* Output coefficients *)
N : INT ; (* Length of output history *)
END_VAR
VAR_OUTPUT XOUT : REAL := 0.0 ; END_VAR
VAR (* NOTE : Manufacturer may specify other array sizes *)
XI : ARRAY [0..128] OF REAL ; (* Input history *)
XO : ARRAY [0..128] OF REAL ; (* Output history *)
I : INT ;
END_VAR
XO[0] := XOUT ; XI[0] := XIN ;
XOUT := B[0] * XIN ;
IF RUN THEN
FOR I := M TO 1 BY -1 DO
XOUT := XOUT + A[I] * XO[I] ; XO[I] := XO[I-1];
END_FOR;
FOR I := N TO 1 BY -1 DO
XOUT := XOUT + B[I] * XI[I] ; XI[I] := XI[I-1];
END_FOR;
ELSE
FOR I := 1 TO M DO XO[I] := 0.0; END_FOR;
FOR I := 1 TO N DO XI[I] := 0.0; END_FOR;
END_IF ;
END_FUNCTION_BLOCK