Pipe — Unidirectional Pipe

Pipe connects a WritePort and a ReadPort through one SPSC byte queue to form a one-way channel: the writer copies data into the queue and the reader copies it from the same queue into its buffer, with no intermediate buffer between the two ports. It is used for data forwarding and loopback tests between threads, tasks or ISRs and tasks.

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Feature Overview

• The write port owns a queue of buffer_size bytes; the read port reads that queue directly.
• A write completes once its data is queued and the reader is notified, without waiting for the data to be read; a pending read is satisfied by the write and may complete inside the write call.
• Completion modes on both ends are those of ReadPort / WritePort, selected by Operation.

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Public API

class Pipe {
public:
  // Construct with the capacity (bytes) of the shared data queue
  explicit Pipe(size_t buffer_size);

  // Non-copyable / non-assignable
  Pipe(const Pipe&) = delete;
  Pipe& operator=(const Pipe&) = delete;
  ~Pipe();

  // Port access
  ReadPort&  GetReadPort();
  WritePort& GetWritePort();
};

• buffer_size: shared queue capacity in bytes; must be greater than 0 and cannot change.
• Pipe has no Size() or similar methods; use the port interfaces via GetReadPort() / GetWritePort().
• The destructor neither cancels requests nor frees the queue storage.

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Usage

Pipe works as an in-memory pipe with a built-in loopback driver: a write notifies the read side, which satisfies a pending read.

LibXR::Pipe pipe(256);

auto& r = pipe.GetReadPort();
auto& w = pipe.GetWritePort();

std::atomic<LibXR::ReadOperation::OperationPollingStatus> rs{
    LibXR::ReadOperation::OperationPollingStatus::READY};
std::atomic<LibXR::WriteOperation::OperationPollingStatus> ws{
    LibXR::WriteOperation::OperationPollingStatus::READY};
LibXR::ReadOperation rop(rs);
LibXR::WriteOperation wop(ws);

uint8_t buf[16];
const uint8_t data[16] = {};

r({buf, sizeof(buf)}, rop);    // not enough data yet: the read pends, rs becomes RUNNING
w({data, sizeof(data)}, wop);  // the write completes the read: rs and ws become DONE

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Pipe write completion means the bytes entered the shared queue; it does not wait for the reader to consume them. When the queue lacks space, the write returns FULL.