There may be a performance impact involved.

Running under a single call.
This required increasing variable size from u8 to u16.

Avoids constant comparison against wx by cmputing the initial windows index.

By avoiding many of the GBC required operations in the drawing pipeline.

The performance should be poor as there're lots of if clauses.

By computing only the color associated with the byte in question.
This avoid computation that was not required.

Allows usage of tiles from multiple VRAM banks.

Created more panic conditions for the KEY0 and KEY1.

The background attributes seem to be failing.

The code is still pending extensive test and some errors may exist.

Still pending processing and conversion to RGB8888.

Still requiring a lot of operational work to allow proper working.