candleLight, CANable, CANnectivity and cantact adapters speak gs_usb. On
Linux and macOS the kernel driver exposes them as SocketCAN interfaces, so
SavvyCAN already reached them through Qt SerialBus. Windows has no such
driver, which left those adapters unusable there.
Add a GSUSBConnection that talks to the hardware directly over WinUSB:
- one connection per physical device, one SavvyCAN bus per CAN channel
- CAN FD including BRS, plus RTR, extended IDs and error frames
- known good bit timings for 16/48/80/160/170 MHz device clocks, with a
generic solver for clocks the tables do not cover
- hardware timestamps, unwrapped across the 32 bit rollover and anchored
to the host clock so they line up with the rest of SavvyCAN
gs_usb multiplexes every channel over a single USB bulk IN endpoint, so a
single reader thread drains it and hands frames to the connection thread in
batches, coalescing the wakeups. That keeps one producer on the lock free
queue, which the tx echo path already writes to.
Device scans skip adapters that a live connection holds. candle_dev_open()
shares the file handle and queues read URBs immediately, so probing a device
in use would consume frames the open connection is waiting for.
connections/candle_api is an unmodified copy of the candle Windows API, LGPL
3.0 rather than MIT and only compiled into Windows builds. See its README for
provenance.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XZnuZJ7zc3e8hk6C8bGDZN
