AnnexF/diffeq_st.txt
author Andrey Skvortsov <andrej.skvortzov@gmail.com>
Sun, 14 Oct 2018 20:14:13 +0300
changeset 1073 24ef30a9bcee
parent 0 fb772792efd1
permissions -rwxr-xr-x
revert commits improved performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR)

Following commits are reverted:
mjsousa 0b275a2 improve performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR) -- increase hardcoded limit to 499
mjsousa 2228799 improve performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR) -- Add comments!!
mjsousa ce81fa6 improve performance of some extensible Standard Functions (ADD, MUL, AND, OR, XOR)"

The reason is that they cause regression in some cases (if function is
used as argument for function block, for example) and this is not
fixed for a long time.
 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