Tools Kindlebt - A Bluetooth library for HF Kindles 11th gen and up

[Sighery]

After a lot of digging in Kindle internals, it's finally ready for use: a C library exposing Bluetooth capabilities on Kindles.

There's quite a lot of caveats however: only for devices from 11th gen and up, only for HF firmwares, and only some Bluetooth operations (mainly just BLE ones) are currently implemented.

Kindles below the 11th gen will never be supported. This is because the 10th gen seemingly used a different Bluetooth stack (BlueZ) from newer devices (Bluedroid). And devices before the 10th gen didn't have Bluetooth hardware.

SF support is technically possible but quite challenging so left unimplemented for now.

Current implemented Bluetooth features (as of writing this post, check the documentation and public API for latest):
* Connect/Disconnect a BLE device
* Set the Kindle up as a GATT Client
* Discover/Retrieve the services of a remote GATT Server
* Read/Write a GATT Characteristic
* Write a GATT Descriptor
* Enable/Disable notifications on a GATT Characteristic

You can find the source code here: https://github.com/Sighery/kindlebt
The documentation here: https://sighery.github.io/kindlebt/
And the releases here: https://github.com/Sighery/kindlebt/releases

The documentation goes more into detail on limitations and usage, as well as the current public API, from which you can see the Bluetooth operations that are currently implemented.

THIS IS JUST A LIBRARY. It's not an application, by itself is not useful, but it allows developers to use it and build applications with Bluetooth functionality on top. Think an engine on a car, by itself useless, but a mechanic can build a car around it and make use of the engine.

I am working on building a Kindle remote page turner using kindlebt, but it's still work in progress and not ready for release. Either way, that would be a separate project and thread when/if that gets released.

Also I'd like to thank @clint32 and @hardfloat who have helped me quite a bit with debugging and reverse engineering of the underlying Bluetooth stack.