Gameboy Development Forum

Hi Antonio, thanks for your reply.

As I guess that GBT Player is geared towards 64kb+ roms (because most "real" games are at least 64kb), is there any step to "configure" it to a 32kb Rom, besides declaring that the song will be stored in "Bank1" when converting it with mod2gbt?

For example, in the make.bat file how should the final line (the one that collapse all the .o files into the gb rom) be used?

The one from your example will always compile to a 64kb rom (working):
"lcc -Wa-l -Wl-m -Wl-j -DUSE_SFR_FOR_REG -Wl-yt1 -Wl-yo4 -Wl-ya0 -o bitbitjam4.gb bitbitjam4.o output.o gbt_player.o gbt_player_bank1.o"

I've tried to remove all the additional parameters to see if it reverted it back to 32kb:
"lcc -Wa-l -Wl-m -Wl-j -DUSE_SFR_FOR_REG -o bitbitjam4.gb bitbitjam4.o output.o gbt_player.o gbt_player_bank1.o"

This one output a 32kb rom indeed, but it's non fonctional: BGB is throwing errors about the rom size and the game doesn't run.

As it's my first GB game, I may be doing some things wrong (the lcc parameters are still mysterious to me).

For now, I just tried to add GBT Player to my game and make it play the "template song".

I'm using the latest GBDK (2.96a I guess), downloaded from sourceforge, alongside with the GBT "legacy" version from your github repo.

Thanks a lot for your help!

Thanks for your help.

Here is a zip with my source and the gbt player component I use, alongside with the make.bat file
http://test.ludoscience.com/sheepitup/gbtest.zip

I've made some additional test with the compiler parameters, and the problem really lies in the number of bank.

If i use the "-Wl-yo4" switch to set 4 banks, everything works fine. If I set "-Wl-yo2" to reduce it to two bank (or if I remove the parameter), I get the following error:
"ERROR: only 1 32kb segment with 2 bank"

Then the .gb file isn't created (it's a 0kb file) and so BGB can't run it.

I'm 100% sure that the problem is your compiler. Some versions of GBDK don't store "const" data in the ROM, they store it in the RAM and copy it when booting. This means that an array that would need just a few hundreds of bytes ends up taking KBs.

I don't know which version of GBDK works fine, though. Maybe you could check the tutorial of the ZGB library and download that version.

Some code of GBT is in bank 1 to leave more space of bank 0 for the rest of the game. You can change it to bank 0, but I wouldn't do it.

Hi Everyone,

Thanks a lot for your help and you explanations, now it's working great!

As @ssjason123 explained, removing both the pragma and the .area _CODE1 made it compile successfully, and playing music too! You're wonderful, my project will have music now .

Thanks @ISSOtm for the explanation about why this wasn't working: I always though that a 32kb ROM was actually a "Bank0+Bank1" rom. I didn't knew that the lack of a MBC means that the game doesn't know what a "bank" is .

@Antonio: I do use the latest GBDK version, coming directly from Zalo ZGB tutorial (actually, it's in this tutorial that I discovered the wonderful gbt player). Thanks a lot for the time you took to help me, even if I use an outdated GBT Player for GBDK compatibility (if one day I learn ASM, I'll be able to try my hand at the latest version )

Thanks again a lot for your help, I couldn't have figured this out without you all!

Now, I'll try to compose something for the game before the bitbitjam4 deadline, but this will be useful for all my (hopefully) next games too .

Last edited by drludos (2017-07-07 09:50:42)