@bun-win32/winusb

Zero-dependency, zero-overhead Win32 WinUSB bindings for Bun on Windows.

Overview

@bun-win32/winusb exposes the public winusb.dll API using Bun's FFI. It provides a single class, WinUsb, which lazily binds native symbols on first use. You can optionally preload a subset or all symbols up-front via Preload().

The bindings are strongly typed for a smooth DX in TypeScript.

Features

• Bun-first ergonomics on Windows 10/11.
• Direct FFI to winusb.dll (USB device I/O, control transfers, pipe management, isochronous transfers, and more).
• In-source docs in structs/WinUsb.ts with links to Microsoft Docs.
• Lazy binding on first call; optional eager preload (WinUsb.Preload()).
• No wrapper overhead; calls map 1:1 to native APIs.
• Strongly-typed Win32 aliases (see types/WinUsb.ts).

Requirements

• Bun runtime
• Windows 10 or later

Installation

bun add @bun-win32/winusb

Quick Start

import Kernel32, {
  FileAccess,
  FileCreationDisposition,
  FileShareMode,
  INVALID_HANDLE_VALUE,
} from '@bun-win32/kernel32';
import WinUsb, { DeviceInformationType } from '@bun-win32/winusb';

// Open a WinUSB device (path from SetupAPI device enumeration)
const devicePath = Buffer.from('\\\\.\\USB#VID_XXXX&PID_XXXX#...\\{GUID}\0', 'utf16le');
const deviceHandle = Kernel32.CreateFileW(
  devicePath.ptr,
  FileAccess.GENERIC_READ | FileAccess.GENERIC_WRITE,
  FileShareMode.FILE_SHARE_READ | FileShareMode.FILE_SHARE_WRITE,
  null!,
  FileCreationDisposition.OPEN_EXISTING,
  0,
  0n,
);

if (deviceHandle === INVALID_HANDLE_VALUE) {
  throw new Error(`CreateFileW failed: ${Kernel32.GetLastError()}`);
}

// Initialize WinUSB on the device
const handleBuf = Buffer.alloc(8);
if (WinUsb.WinUsb_Initialize(deviceHandle, handleBuf.ptr)) {
  const interfaceHandle = handleBuf.readBigUInt64LE(0);

  // Query device speed
  const speedBuf = Buffer.alloc(1);
  const lenBuf = Buffer.alloc(4);
  lenBuf.writeUInt32LE(1, 0);
  WinUsb.WinUsb_QueryDeviceInformation(interfaceHandle, DeviceInformationType.DEVICE_SPEED, lenBuf.ptr, speedBuf.ptr);
  console.log('Device speed:', speedBuf.readUInt8(0));

  WinUsb.WinUsb_Free(interfaceHandle);
}
Kernel32.CloseHandle(deviceHandle);

[!NOTE] AI agents: see AI.md for the package binding contract and source-navigation guidance. It explains how to use the package without scanning the entire implementation.

Examples

Run the included examples:

bun run example:descriptor-visualizer
bun run example:usb-device-inspector

Notes

• Either rely on lazy binding or call WinUsb.Preload().
• Windows only. Bun runtime required.
• SAL types & naming: nullability is in the type — Optional<T> (formally optional, SAL _*opt_) and Nullable<T> (plain [in]/[out] the docs say can be NULL), the null sentinel derived from T (null for pointers LP*/P*, 0n for handles/by-value addresses); direction is in the parameter name — _out (_Out_), _in_out (_Inout_), _In_ bare. See AI.md and the repo AGENTS.md.