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haroldoop · Posted: Sat Feb 25, 2006 10:13 pm

I've been working on adapting z88dk, a C cross-compiler for Z80 systems, to generate Sega Master System ROMs.
The attached file includes both a z88dk runtime library for SMS ROMs and an very simple example project. It still doesn't do much, since I haven't finished the libraries for it yet, but it already runs perfectly on an emulator. ;)
Of course you'll also have to download z88dk in order to compile the source.

** updated **
2006-03-07

Now most of the absolutely necessary functions are implemented. You can already set the palette, set the tileset, define the bkg map, and position the sprites.

** updated **
2006-03-11

Now, you have everything you need to make SMS games in C... except sound.
- Added joystick reading routines;
- Created an include file;
- Created a tool to convert z88dk's map files into Meka/Emukon-compatible symbolic definition files. This will allow the debuggers built into those emulators to correctly label the subroutines/variables of your program.

** updated **
2006-03-26

-Added partial stdio.h support (write-only)
-Fixed a joystick reading bug
-Added an example game

** updated **
2006-04-12

-Added support for apLib decompression (based on Maxim's code)
-Improved the example game
-Added an example for the decompression routine
-Added a small utility for padding the ROM to 32k and adding the standard SEGA header to it

** updated **
2006-04-23

-Added support for the PAUSE button
-Added support for the VBL/HBL interrupt (doesn't work correctly yet)
-Added sound support

** updated **
2006-04-23

-Updated "sms.h" (I had sent an older version by mistake)
-Added some missing source

patroclus · Joined: 31 Jan 2006 Posts: 69

Would be great if it runs at good speed on real system :)
I have to test that, thank you

Heliophobe · Posted: Sun Feb 26, 2006 9:46 am

I've also had a crack at using z88dk for SMS development. What tripped me up was that I couldn't convince the compiler to put global variables and arrays in SMS ram - it seems z88dk wasn't written with ROM based z80 machines in mind so global variables are assigned to locations inside the executable, therefore they will be in ROM, not RAM. Local variables are stack allocated so they are still usable, and I suppose one could depend on them exclusively as a workaround. Alternately you could compile your code to run with an origin of $c000 and use a rom stub to copy the executable into RAM, but you'll run out of RAM real fast that way.

Other than that, some of the code it generates is painfully slow -- adding two chars, for instance, causes the compiler to promote both variables to 16 bit, push them onto the stack, and the call an adding function, at least in the version I tested. Of course compotently written hand-written assembly code is going to beat compiled code every time but it seems like a better optimizer would be needed to really do a lot with z88dk, but I suppose with a very good support library written in assembly, it should be possible to use it to do puzzle games or some very simple action games.

haroldoop · Posted: Sun Feb 26, 2006 2:43 pm

Actually, I intend to use it to make RPGs and puzzle games. ;)

Heliophobe · Posted: Sun Feb 26, 2006 10:55 pm

Well then, there you go.

Probably the best approach would be to have a strong game engine written in asm, and use C to control it all, as sort of a scripting language (sort of).

For accessing roms above 48k, you might want to create some sort of virtual rom file system for the C code to use to load assets into vram.

Marty · Joined: 19 Dec 2005 Posts: 33 Location: Thailand

Heliophobe · Posted: Wed Mar 01, 2006 6:11 pm

Heliophobe · Posted: Wed Mar 01, 2006 6:26 pm

Ah, DEFVARS seems like the command you'd need to move those into static RAM. Missed that the last time around. I wonder if z88dk still lets you put constant data in ROM if you do that. I imagine so.

haroldoop · Posted: Wed Mar 08, 2006 3:53 pm

Libraries updated!
(see first post)

xavier · Joined: 31 Dec 2004 Posts: 76 Location: France

Seem very promising :)

haroldoop · Posted: Sun Mar 12, 2006 2:02 am

There's now a new version of the libraries. Now you can actually make games with it! ;)
(Se first post for the download link)

haroldoop · Posted: Sun Mar 26, 2006 12:10 pm

New version posted. Now comes with an example game! :)
(See first post)

haroldoop · Posted: Thu Apr 13, 2006 1:09 am

New release available, with data decompression support.

haroldoop · Posted: Sun Apr 23, 2006 10:41 pm

There's a new version available with pause and sound support.

haroldoop · Posted: Tue Apr 25, 2006 2:44 am

* NEW BUGFIX RELEASE *
The version that I had released in 2004-04-23 wouldn't work.
I have released a new version to fix this problem.
Sorry for my mistake. =P

probert · Posted: Wed Apr 26, 2006 12:13 pm

I guess you wanted to say 2006-04-23 :)

Best Regards, man.

haroldoop · Posted: Wed Apr 26, 2006 3:40 pm

Okay, sorry for that mistake, too. XD

haroldoop · Posted: Thu Jun 07, 2007 1:32 pm

Good news: SMS support was added to the official z88dk.
http://www.z88dk.org/