Sprites updated with HDMA differs from hardware

[GValiente]

Test rom:
test.zip

The first sprite lines in the image with length = 64 pixels are not shown on hardware.
Those lines are present in the last line of the sprite's image data.

[fleroviux]

@GValiente can you provide source code to this test? this would make it a lot easier to debug for me.

[GValiente]

The test has been built on top on an engine that I'm planning to release at the end of this year, so if you don't mind to wait a few months I'll release the source code of this test with it.

If you can't wait, I can release part of the issues' related code. I think that the issue is related with that hdma on hardware in my rom seems to be two horizontal lines late, instead of only one.

[fleroviux]

I'm a bit confused how many lines are actually supposed to be missing on HW:

this is what I get on my GBA SP (sorry for the poor lighting condition). Can you confirm that all sprite lines with width=64 should be missing as seen on the image?

If you can't wait, I can release part of the issues' related code. I think that the issue is related with that hdma on hardware in my rom seems to be two horizontal lines late, instead of only one.

I guess that might help but I had hoped to be able to make changes and test them on HW.

[GValiente]

Yep, those are the lines that are missing, the top ones with width=64, which are rendered with the last line of the sprite's tiles:

https://cdn.discordapp.com/attachments/312199400875360256/749564712437678160/example.png

[GValiente]

New test ROM.

The two biggest lines in the middle of the diamond are not visible on a real GBA:

The source code of the test ROM is available here.

[fleroviux]

Thanks!

[fleroviux]

This should perfectly match hardware now.