Method offToIdx

chapter21/src/test/java/com/seaofnodes/simple/Eval2.java:314–320

( long off, TypeStruct t)

    // Convert array size to array element count
    private static int offToIdx( long off, TypeStruct t) {
        off -= t.aryBase();
        int scale = t.aryScale();
        long mask = (1L << scale)-1;
        assert (off & mask) == 0;
        return (int)(off>>scale);
    }

    // Builds and returns a pointer Object
    private static Object alloc(NewNode alloc) {