chore: scaffold CMake build system

Add the CMake build for the Swift + C++ macOS port, mirroring the
refix layout: deps/ modules (Platform, Flags, Sanitizers, FindUnity),
per-module static libraries (usb, auth, mt76, gip, hid, api), a Swift
app entry point with a pure C bridge header, and a Unity test suite
behind BUILD_TESTING.

Swift requires the Ninja or Xcode generator; a guard in
CMakeLists.txt rejects anything else.

Co-Authored-By: qwen (qwen/qwen3.8-27b@q2_k_xl): scaffolded CMake build + tests

include/app/xone_api.h

@@ -0,0 +1,24 @@
+#pragma once
+
+// ==============================================================================
+// C ABI bridge between the C++ protocol stack and the Swift app layer
+// ==============================================================================
+// This header is imported into Swift via -import-objc-header, so it must stay
+// pure C (no C++ types). The C++ modules implement these entry points.
+// ==============================================================================
+
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// Human-readable version string of the protocol stack.
+const char *xone_version(void);
+
+// TRUE if an Xbox Wireless Dongle is connected, FALSE otherwise.
+bool xone_dongle_present(void);
+
+#ifdef __cplusplus
+}
+#endif

include/auth/crypto.hpp

@@ -0,0 +1,16 @@
+#pragma once
+
+// ==============================================================================
+// Auth + crypto
+// ==============================================================================
+// Port target: medusalix/xone auth/auth.c + auth/crypto.c.
+// ECDH (P-256) key agreement, RSA encryption, SHA transcript/PRF for the GIP
+// authentication handshake. AES-CCMP frame encryption itself runs on-chip;
+// this layer only derives and installs keys into the MT76 WCID registers.
+// ==============================================================================
+
+namespace xone::auth {
+
+// TODO(phase 1): ECDH/RSA/SHA primitives (CommonCrypto / Security.framework).
+
+} // namespace xone::auth

include/common/types.hpp

@@ -0,0 +1,49 @@
+#pragma once
+
+// ==============================================================================
+// Platform types and endianness helpers (user-space)
+// ==============================================================================
+// Replaces the kernel's __le16/__le32/guid_t machinery for user-space use.
+// All wire formats of the MT76 chip and the GIP protocol are little-endian;
+// these byte-wise helpers stay correct on any host endianness.
+// ==============================================================================
+
+#include <cstdint>
+
+namespace xone {
+
+// 128-bit GUID used by the GIP protocol (port of the kernel guid_t).
+struct guid_t {
+    std::uint8_t data[16];
+};
+
+inline auto load_le16(void const *p) -> std::uint16_t
+{
+    auto const b = static_cast<std::uint8_t const *>(p);
+    return static_cast<std::uint16_t>(b[0] | (b[1] << 8));
+}
+
+inline auto store_le16(void *p, std::uint16_t v) -> void
+{
+    auto *b = static_cast<std::uint8_t *>(p);
+    b[0] = static_cast<std::uint8_t>(v & 0xFF);
+    b[1] = static_cast<std::uint8_t>((v >> 8) & 0xFF);
+}
+
+inline auto load_le32(void const *p) -> std::uint32_t
+{
+    auto const b = static_cast<std::uint8_t const *>(p);
+    return static_cast<std::uint32_t>(
+        b[0] | (b[1] << 8) | (b[2] << 16) | (static_cast<std::uint32_t>(b[3]) << 24));
+}
+
+inline auto store_le32(void *p, std::uint32_t v) -> void
+{
+    auto *b = static_cast<std::uint8_t *>(p);
+    b[0] = static_cast<std::uint8_t>(v & 0xFF);
+    b[1] = static_cast<std::uint8_t>((v >> 8) & 0xFF);
+    b[2] = static_cast<std::uint8_t>((v >> 16) & 0xFF);
+    b[3] = static_cast<std::uint8_t>((v >> 24) & 0xFF);
+}
+
+} // namespace xone

include/gip/protocol.hpp

@@ -0,0 +1,15 @@
+#pragma once
+
+// ==============================================================================
+// GIP protocol (Game Input Protocol)
+// ==============================================================================
+// Port target: medusalix/xone bus/protocol.c + bus/bus.c.
+// Client lifecycle, ANNOUNCE/IDENTIFY handshake, auth handshake, status
+// reports (battery, connected), HID report pass-through.
+// ==============================================================================
+
+namespace xone::gip {
+
+// TODO(phase 1): GIP frame types, client lifecycle, handshake state machine.
+
+} // namespace xone::gip

include/hid/hid_device.hpp

@@ -0,0 +1,16 @@
+#pragma once
+
+// ==============================================================================
+// Virtual HID gamepad presentation
+// ==============================================================================
+// Exposes connected controllers to macOS so games recognize them natively.
+// Preferred path: DriverKit extension implementing IOHIDDriver with an
+// Xbox 360/One-compatible report descriptor (input reports from GIP, output
+// reports for rumble relayed back via GIP).
+// ==============================================================================
+
+namespace xone::hid {
+
+// TODO(phase 4): report descriptor + virtual device presentation.
+
+} // namespace xone::hid

include/mt76/mt76.hpp

@@ -0,0 +1,20 @@
+#pragma once
+
+// ==============================================================================
+// MT76 chip protocol (MediaTek MT76xx radio in the dongle)
+// ==============================================================================
+// Port target: medusalix/xone transport/mt76.c + mt76.h + mt76_defs.h.
+// Firmware load (0x3800-byte chunks), EFUSE read, radio init (~80 register
+// writes), channel evaluation, beacon transmission, pairing mode, client
+// association and WCID/AES-CCMP key setup (encryption runs on-chip).
+// ==============================================================================
+
+#include <cstdint>
+
+namespace xone::mt76 {
+
+// Load the firmware image for the given dongle PID into the chip.
+// TODO(phase 3): port from xone_mt76_load_firmware().
+auto load_firmware(std::uint16_t pid, char const *firmware_path) -> bool;
+
+} // namespace xone::mt76

include/usb/usb_transport.hpp

@@ -0,0 +1,25 @@
+#pragma once
+
+// ==============================================================================
+// USB transport (IOKit / IOUSBFamily)
+// ==============================================================================
+// Owns the physical Xbox Wireless Dongle:
+//   VID 0x045E, PIDs 0x02E6 (old), 0x02FE (new), 0x02F9 (ASUS/Lenovo built-in),
+//   0x091E (Surface Book 2).
+//
+// Port target: medusalix/xone transport/dongle.c + transport/mt76.c USB calls.
+// Linux usb_control_msg()/usb_bulk_msg() map to IOUSBDeviceInterface
+// DeviceRequest / IOUSBInterfaceInterface WritePipe+ReadPipe.
+// ==============================================================================
+
+#include <cstdint>
+
+namespace xone::usb {
+
+// Probe for a connected dongle and claim its WLAN interface
+// (bInterfaceNumber 1).
+// TODO(phase 2): IOKit implementation (IOServiceMatching, interface open,
+// EP 0x04 bulk in/out + EP 0x05 interrupt in).
+auto probe() -> bool;
+
+} // namespace xone::usb