See https://sourceforge.net/p/gnuboy/wiki/ and [Features] for more information and the sister project [OhBoy] (OhBoy is gnuboy for SDL with a simple menu system).
gnuboy is a portable Gameboy emulator originally created by Laguna and Gilgamesh, many forks appeared and these were organized into one clean codeline by clach04. See [GNUBoyHistory] for more details.
For building see [BuildNotes].
Documentation is available in https://sourceforge.net/p/gnuboy/code/HEAD/tree/trunk/docs/ the document most users will be interested in is the https://sourceforge.net/p/gnuboy/code/HEAD/tree/trunk/docs/CONFIG configuration doc, that talks about key remapping (amongst other things).
There are various [Ports] of gnuboy, some with enhancements. https://sourceforge.net/p/gnuboy/code/21/ 21 and earlier are the original sources.
This project is currently focused on:
gnuboy is also known to build/run on the Pandora (ARM) and Caanoo (ARM).
== How you can help ==
Wiki: BuildNotes
Wiki: Features
Wiki: GNUBoyHistory
Wiki: OhBoy
Wiki: Ports