Super Gameboy MSU1

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Post by Conn on Thu 9 Jan 2020 - 8:09

Here are some notes for developing Super Gameboy MSU1 enhanced games.

Tools:
- BGB gameboy emulator and debugger: http://bgb.bircd.org/
- Bass with  lr35902.arch: https://drive.google.com/open?id=1Py0KY2ur7ylGCGRHUEVFd70O1zi7P8-O
- bsnes 114 to test: https://byuu.itch.io/bsnes
- bsnes plus with sgb debugger (dev built, not official yet): https://ci.appveyor.com/project/devinacker/bsnes-plus/builds/29964034/artifacts

Check the example codes in the bass zip files.

Here are some noted for Zelda Link's Awakening DX which probably is the next project. I myself think that I will not participate, but with luck qwertymodo is up to Wink


Breakpoint
R01B: 4032 CD 3B 41 Call 413b
(pc: 0x6c032: cd 3b 41)

Here at:
1b:4032: set both d368 and d369 to (00 00) to mute. If you put another theme here, like 22 22 you hear the owl music


The track number is in a:
1a intro
0d title when button pressed during intro
11 name entry
01 title when watching full intro
1c in bed
10 receive shield
1d pre-sword (village, houses)
22 owl at sword
0f getting sword
(ff mute)
31 victory about getting sword + "zelda music afterwards
04 village
0a inside house
05 zelda music at beach

All themes seem to be different when hooked at this place. rom bank 1b has some place at the end starting at pc: 0x6ced6 until 0x6cff0; so easy to hook and write a code here.

Here's a track map:
https://github.com/zladx/LADX-Disassembly/blob/master/src/constants/sfx.asm
(not very correct I think though, for the used breakpoint)

Super Gameboy MSU1 Image418

I do not know how to differ the breakpoints to read from a specific rom bank (neither possible in bsnes nor bgb to set the rom bank (this case 1b)). Best is to get to this breakpoint is to make a write breakpoint at d369, eventually it will break at 1b:4031, and you can set this breakpoint 1b:4032 to map the track


Last edited by Conn on Tue 21 Jan 2020 - 7:39; edited 1 time in total
Conn
Conn

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Since : 2013-06-30

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Super Gameboy MSU1 Empty Re: Super Gameboy MSU1

Post by Conn on Mon 13 Jan 2020 - 18:49

Here's some code for Link's Awakeing described above, problem:

SGB cannot emulate GBC, so you loose the color dungeon unfortunately. It is what it is and we have what we have.

This patch is only a try, it works so far but after a non-loop track (shield) it does not get back to the initial track (I think this can be overcome with some coding, e.g.,:
after getting the shield, the game does not resume to the initial out of bed theme ($1c). I guess there is some ingame stuff making that after this shield acquired theme ($10) is played over it gets back. I tried by giving the looping theme 04 instead 10 and then it also does not switch back to 1c... so here's some further ingame stuff running. But you can try out my code if you like
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