Volatile loads and stores, for memory-mapped I/O.

The interface is Nim's std/volatile — same names, same signatures — so source written against that module compiles here unchanged. What differs is the implementation: Nim emits a C cast through a volatile*, while here the access IS the intrinsic and the guarantee is stated in its row rather than delegated to a C compiler.

What the guarantee is:

• the access HAPPENS, exactly once, wherever it is written. It is never

deleted for producing a value nobody reads, never duplicated, and never merged with another access to the same address.

• it is ONE access, at exactly the pointee's width. A cell too wide for the

target's load is refused by name rather than split into two — two accesses is not what was asked for, and for a device register the difference is observable.

• it is not reordered against another volatile access.

What it is NOT: a barrier, and not ordered against ORDINARY memory. That is the same line C draws, and it is drawn there because a peripheral write does not flush a store buffer. Where a device needs more, the barrier instructions are their own thing.

volatile is deliberately not a type qualifier. A qualifier is viral — it reaches every type comparison, every signature, every generic instantiation — to express a property that belongs to the ACCESS and not to the memory.