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  • Joined: 06 Aug 2021
  • Posts: 18
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Bank switching with devkitSMS
Post Posted: Wed Oct 20, 2021 8:44 pm
Hey, I've been working on a project in devkitSMS, and I need to start using bank switching. I've looked over the resources on the git, but when I run my build.bat it doesn't work. The last working batch file I had looked like this:


@echo off

REM Here we have assets for everything up to the title screen
assets2banks ..\gfx

sdcc -c -mz80 bank2.c

sdcc -c -mz80 main.c

sdcc -o output.ihx -mz80 --data-loc 0xC000 --no-std-crt0 ..\crt0\crt0_sms.rel main.rel ..\lib\SMSlib.lib bank2.rel

..\utl\ihx2sms output.ihx output.sms


What do I need to change in order to have more banks for graphics?

I also tried using folder2c, but when I do, it keeps creating .c files of size 0 without any assets.

Any help is much appreciated!
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  • Joined: 16 May 2002
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  • Location: italy
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Post Posted: Thu Oct 21, 2021 7:36 am
Did you try reading this?
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  • Joined: 05 Sep 2013
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Post Posted: Thu Oct 21, 2021 7:39 am
Last edited by sverx on Fri Oct 22, 2021 6:56 am; edited 1 time in total
assets2banks will create as many bankN.c files as needed, so you just compile them declaring them as data banks
sdcc -c -mz80 --constseg BANK2 bank2.c
sdcc -c -mz80 --constseg BANK3 bank3.c


then in the linking phase you need to add a switch to tell the linker that the data should go at address 0x8000 and this means for instance adding
-Wl-b_BANK2=0x8000 -Wl-b_BANK3=0x8000
when you have bank2 and bank3

to access the data in the banks, you need to use the
SMS_mapROMBank(n)
macro

check this section: https://github.com/sverx/devkitSMS#how-to-use-more-than-48kib-in-your-rom-rom-pa... for a complete explanation

edit: also, you don't need bank switching if your ROM is 48 KB, but you need it to go over that.
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  • Joined: 06 Aug 2021
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Post Posted: Thu Oct 21, 2021 12:32 pm
Tom wrote
Did you try reading this?


No I hadn't! This is incredibly valuable! I was able to get it working with this and sverx's advice on this thread! Thank you so much!
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