Leyline Audio Driver (C++)

A high-performance virtual audio driver for Windows, re-implemented in C++ from the original Rust codebase. Work in progress.

Project Layout

LeylineAudioDriverCpp/
├── driver/                   # Kernel-mode driver (C++17, WDM)
│   ├── include/
│   │   ├── leyline_common.h    # Shared types: RingBuffer, SharedParameters, IOCTL codes
│   │   ├── leyline_guids.h     # All KS / PortCls GUIDs and constant IDs
│   │   ├── leyline_descriptors.h # KS descriptor table declarations
│   │   └── leyline_miniport.h  # Miniport class declarations + DeviceExtension
│   ├── src/
│   │   ├── driver.cpp          # DriverEntry, DriverUnload
│   │   ├── adapter.cpp         # AddDevice, StartDevice, IRP dispatch, CDO
│   │   ├── wavert.cpp          # CMiniportWaveRT, CMiniportWaveRTStream
│   │   ├── topology.cpp        # CMiniportTopology
│   │   └── descriptors.cpp     # All KS descriptor tables & property handlers
│   ├── leyline.inx             # INF template (identical to Rust project)
│   └── sources                 # eWDK NMAKE build file
├── scripts/
│   ├── LaunchBuildEnv.ps1      # eWDK environment initializer
│   ├── Install.ps1             # Build → deploy → verify pipeline
│   └── Uninstall.ps1           # VM uninstall wrapper
├── test/
│   └── EndpointTester/         # C# tool to enumerate audio endpoints
├── package/                    # Staged build artifacts (gitignored)
├── Makefile                    # GNU Make task aliases
└── README.md

Architecture

The driver exposes four PortCls subdevices:

Name	Class	Role
WaveRender	WaveRT	Renders audio from client apps
WaveCapture	WaveRT	Captures audio to client apps
TopologyRender	Topology	Volume/mute nodes for render path
TopologyCapture	Topology	Bridging for the capture path

Physical connections mirror the Rust project:

• WaveRender (pin 1) → TopologyRender (pin 0)
• TopologyCapture (pin 1) → WaveCapture (pin 1)

Building

Prerequisites

• eWDK (Enterprise WDK) at D:\eWDK_28000 or set LEYLINE_EWDK_ROOT.
• Windows 10 / 11 SDK 10.0.28000.0 or set LEYLINE_SDK_VERSION.
• A Hyper-V VM named LeylineTestVM with snapshot LeylineSnapshot.

Quick Start

# Full build + deploy to VM
.\scripts\Install.ps1

# Build only (no VM)
.\scripts\Install.ps1 -fast

# Clean rebuild
.\scripts\Install.ps1 -clean

# Uninstall from VM
.\scripts\Uninstall.ps1

# Check endpoints on the VM after install
cd test\EndpointTester && dotnet run

Environment Variables

Variable	Default	Description
LEYLINE_EWDK_ROOT	D:\eWDK_28000	Root of the eWDK installation
LEYLINE_SDK_VERSION	10.0.28000.0	WDK / SDK version string
LEYLINE_VM_NAME	TestVM	Hyper-V VM name
LEYLINE_VM_SNAPSHOT	Leyline	Snapshot to revert before testing
LEYLINE_VM_USER	USER	VM administrator username
LEYLINE_VM_PASS	(required)	VM administrator password
LEYLINE_CERT_PASS	(required)	Code-signing certificate password

Key Design Decisions vs. Rust

• COM via PortCls C++ helpers: CUnknown / DECLARE_STD_UNKNOWN() handle ref-counting, eliminating the manual vtable boilerplate needed in Rust's no_std environment.
• /kernel flag: Suppresses C++ features incompatible with kernel mode (exceptions, RTTI).
• Pool tags: Every new call uses a four-byte pool tag (e.g., 'LLWS') for leak tracking.
• Descriptor tables: Statically initialized in .rdata, same as the Rust #[link_section] approach.
• No CRT: Builds against wdm.lib only; RtlCopyMemory replaces memcpy.