Reading one named register bit #
The leaves of the element loops read single bits of the machine's registers at
computed cells: a ρ-atom of an expansion sentence
is one bit of VAL or MIRROR at the cell whose name marks match a tuple held in
the control, a tag read is the same at a canonical cell. The trip is always
the same: turn off the working-cell marker, scan up to the first cell whose
tracks satisfy the name guard – unique by
DescriptiveComplexity.Draw.eq_of_slotMark_name-style facts – take one step
left reading the walked digit into the phase, and scan back down to the
marker.
DescriptiveComplexity.Draw.Prog.reaches_readBit_pos and _neg are the two
outcomes. The read changes nothing on the tape, so the two theorems mention
one tape; the caller cases on the bit.
Writing one named register bit: the same trip, with the walked track updated at the named cell on the way back down.
Dependency graph
Writing one named register bit, the budget forgotten.
Dependency graph
Reading a set bit: the trip ends at the marker in the positive phase.
Dependency graph
Reading a set bit: the trip ends at the marker in the positive phase.
Dependency graph
Reading a clear bit: the trip ends at the marker in the negative phase.