Xila

Appearance

Peripherals ​

The peripherals crate defines shared data types used to configure and interact with low-level peripherals.

It currently focuses on pin modeling primitives (direction, level, pull mode, and compact data representation) that can be exchanged safely between layers.

Boundaries ​

  • In scope: pin-level enums and packed payload conversions.
  • Out of scope: driver access, pin mux configuration engines, board-specific behavior.

Internal structure ​

  • lib.rs: exports peripheral primitives.
  • pin.rs: enums, PinData, and byte-slice conversion implementations.

Runtime interaction ​

  • Control paths can serialize/deserialize PinData as mutable byte slices.
  • Consumers validate incoming byte buffers via TryFrom<&[u8]> / TryFrom<&mut [u8]> before interpreting as typed data.

Dependency model ​

  • No external runtime dependencies.
  • Consumed by driver layers and any crate requiring shared pin payload contracts.

Failure semantics ​

  • Conversion methods return Err(()) on size/alignment mismatch or invalid enum discriminants.
  • No I/O side effects are performed by this crate itself.

Extension points ​

  • Additional peripheral payload types can be added in separate modules while preserving PinData layout.
  • Existing enums can be extended carefully with ABI/backward-compatibility considerations.

Contract vs implementation ​

  • Contract: repr(u8) enums and repr(C) PinData with conversion helpers.
  • Current implementation: low-level transmute-based conversions with explicit length/alignment validation.

Limitations and trade-offs ​

  • Minimal scope keeps coupling low but pushes richer peripheral semantics to drivers/modules.
  • Raw layout conversion is efficient but requires strict buffer discipline by callers.

References ​