CRT Screen Offset for Game Boy and GBA cores

[wondermagenta]

Hi everyone, I asked about this on the GBA Github page already, but I'm essentially looking for a way to offset the image vertically when playing on my CRT, because for some reason it displays an on-screen message at all times when using the GBA and Game Boy cores.

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Two solutions were suggested: either I build a custom version of each core with one value changed, or I use a custom mode and turn on the VGA scaler option.

The latter solution is something I'd need more information on. As far as I'm aware, it's not really intended for use with non-VGA monitors and will cause problems on a regular CRT. It would also mess up the HDMI output obviously, which isn't ideal. If anyone has input on this I'd appreciate it, since I wouldn't even know how to tweak the values exactly.

As far as building custom cores goes, mirkorean actually replied to my Github thread and built a version of the GBA core with the necessary change. I'm very thankful for this and tested it last night, and it's a huge improvement (only one line is covered up by the on-screen display now, which is IMO acceptable.) But I'd like to be able to build these custom cores myself in the future (especially since I still need a version of the Game Boy core that works for me,) so I was wondering if anyone has advice on how to pull that off?

Hope this thread is appropriate and thank you for reading.

[FPGAzumSpass]

Building is very easy...
- download and install Quartus 17.0 or 17.1 with the Cyclone 5 package (you probably need to create an account) : https://fpgasoftware.intel.com/17.1/?edition=lite
- clone the repository you want to build or download a .zip file of all contents
- start the quartus project *.qpf (not *_Q13.qpf)
- click on the "play" button (start compilation)

10-60 minutes later you will have a .rbf file in the output folder