Just as the zero-radius automata can be very useful for housekeeping purposes without being of particular intrinsic interest, the simpler von Neumann automata can also be exploited to arrange the bitplanes. Shifting, necessarily confined to the four principal directions, but applied independently to each bitplane, is a good example.
The function vnshift(t,l,m) creates a table int *t for shifting one plane; it is just as easy to copy the central cell as to complement it, according to the parameter int l. One of the planes of the pair must be ignored; the parameter int m tells which.
In the four state von Neumann ``plane,'' the states can undergo one of the 24 permutations of a set of four objects, greatly enlarging the concept of a complement. In terms of binary planes, this amounts to passing bits from one plane to the other as well as from one neighbor to another.
Since few housekeeping chores are that elaborate, none of these rules has yet been given a special function of its own within CAMEX . For simple shifts it matters little whether the plane is quaternary or binary.