C++ facade

The optional C++14 facade owns Corelib's fixed storage and delegates every operation to the C11 core. It adds type-safe values and callback bridging; it does not contain another protocol implementation.

Requirements

• A modern 32-bit MCU toolchain with C++14 support.
• Embedded Template Library 20.32.1 or newer within major version 20.
• No exceptions, RTTI, heap, operating system, or C++ standard-library runtime.

For CMake source builds, set CORELIB_ETL_ROOT, enable CORELIB_BUILD_CPP, and link Corelib::DeviceCpp. Installed consumers request the Cpp package component and make ETL discoverable through ETL_ROOT when required.

Ownership

corelib::Device and corelib::Gateway cannot be copied or moved because the C context points into storage owned by the facade object. Create each object in storage that remains valid for the complete connection lifetime. The handler supplied to init() is borrowed and must outlive the facade.

Callback frames, UUIDs, and transaction payloads are borrowed etl::span views. Copy data needed after the callback returns. Callbacks are synchronous and must not call the same context.

Template parameters set memory limits at compile time:

corelib::Device<512, 2, 16, 4> device;

The parameters are maximum message bytes, reassembly slots, outbound frames, and pending requests. Choose the smallest limits that satisfy the device.

Device integration

Derive one long-lived handler and initialise the fixed-storage owner:

class Handler final : public corelib::Handler {
public:
  corelib::SendResult sendFrame(corelib::LinkId, void *,
                                corelib::FrameView frame) override {
    return transportWrite(frame);
  }

  void onTransaction(const corelib::TransactionView &value) override {
    queueRequest(value.id, value.data);
  }
};

Handler handler;
corelib::Device<512, 2, 16, 4> device;
corelib::Config config;

loadProvisionedUuid(config.nodeUuid);
config.maximumTransactionDataSize = 256;
const corelib::Status status = device.init(config, handler);

The same receive, tick, response, publication, and serialisation rules as the C API apply. Operations return corelib::Status; normal failures do not throw or set hidden global state.

Gateway facade

corelib::Gateway<> owns the local Device storage and all gateway pools. corelib::GatewayHandler extends the Device handler with discovery, bootstrap, and topology callbacks. Template arguments bound links, routes, candidates, assignments, forwarding frames, and control reassembly.

Use nativeHandle() only when interoperating with C-only application code. See the C++ API reference for the complete facade. Arduino packaging and the umbrella header are covered in the Arduino guide.