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Setting up 32X dev environment.
RockinB - Nov 26, 2004
    RockinB Nov 26, 2004 
I want to try some 32X coding in C, but haven't got any deeper knowledge of the genesis hardware and the layout of the code inside a cartridge.

This guy Devster is really making progress on 32X dev and I downloaded his WAL-MARSX genesis-cd-32X dev tool. But it's only for asm.

There is also an example from fvr webring, but I don't know which compilers they used and if they are even using the 32X to run code.

Can I use the Saturn SH2 C-compiler from KPIT?

    antime Nov 26, 2004 
KPIT's package should work just fine, but you will need a linkscript and startup code.

    Kaneda Nov 29, 2004 
Fonzie use C so I think you can ask him for information

    RockinB Dec 1, 2004 
Good news to follow...

I PMed fonzie about that and he wrote:


  
Hi,

I'm crap in ASM SH2 so you'll notice that my demos uses only 68k (sh2's are looping in their cache ram).

In fact, the sega genesis code need to be compilated @ 0x880000 because when the 32x is enabled, the cartridge acces from genesis shift to 0x880000 (magic!).

Also, you need to have a good genesis rom header (the 32x/md header used in all 32x games).

Because this header (compiled @ 0x0) do that:

-Define where sh2 code starts (main and sub)

-Makes the genesis copy a little program in his ram

-Genesis jump on it.

-Genesis enable the 32x (both sh2 jumps on their code, cartridge shift @ 0x880000)

-Genesis (RE) jmp on the cartridge on the code compilated @ 0x880000

And all is ready for use!

So using GCC to build a 32x rom was never made (imagine else, WOW i want it, I want it!).

So you should contact Devster if you want more informations because I never made any 32x stuff using the sh2 and i would be very happy if you make a gcc packtage for 32X.

Btw: If you look at walmarsx sources, you'll find some important infos in maincode.68k (about the 32x rom structure / header).

Bye and good luck.

Fonzie


So I've had a look at maincode.68k of devsters WalMarsX and saw there are master.bin and slave.bin included.

If we somehow get these .bin files externally created via compiling C-files, we may have a working 32X game.

But my problem is: devster provides links to WinXP versions of snasm68K and snasmsh2...the first one really is WinXP compatible,

but the latter one (as well as all snasm tools) does not work under XP,

instead it gives the error:

Code: 
  
INTERRUPT 0DH, GENERAL PROTECTION FAULT possible illegal address error code = 0000 eax = 00000000 esi = 00047000 flags = 3202 ds = 01C7 ebx = 00047000 edi = 000404F0 eip = 000011D1 es = 01C7 ecx = 00047000 ebp = 00000000 cs = 01BF fs = 0000 edx = 00000000 esp = 00046F08 ss = 01C7 gs = 0000
Furthermore the demo GNUSNASM from the official 32x devkit shows a way how to call C-functions from asm code.

But as long as snasmsh2 does not work, I can't use WallMarsX.

The good news starts here:

I've worked on recompiling the GNUSIERA example using the usual Saturn GNUSH compiler from KPIT!

Then I ran into problems while linking with ld (libc and libgcc were not included, I found out later),

1st try:

I recompiled every single library of the example, found a bug in ASM code(hehe),

one in C-code and besides deprecated notation warning concerning asm files, it worked.

OK, for some unknown reason, make says: no rule to make target *.c or *.s,

although the makefile got:

Code: 
  
.c.o: $(CC) $(CFLAGS) -c $(INCLUDES) $< .s.o: $(AS) $(ASFLAGS) $(INCLUDES) -o $@ $<
So I had to list the files explicitly. Any clue on that?

It's fine, but the linking problem wasn't gone.

2nd try:

I realized that two libraries where missing,

so the next try was to just take libc.a and libgcc.a from the saturn compiler.

But the linker had an unknown reference to atexit() and I don't know where I can find this.

3rd try:

Unlike the GNUSIERA example, the Saturn SGL samples don't use ld, but gcc to link.

So I tried very carefully to adapt this(beware: I don't know much about linking and such tools).

And yes, it works. Everything could be recreated(rom.bin, sdram.bin),

but this example is for the CartDev 32x devkit (guess it, I don't got one) and the upload(to devkit) utility seems to place

the files at the right location:

Code: 
  
toaddr 0x60c0000 1 0xf1 toaddr 0xe000001 1 0x7f toaddr 0xe000000 0 0x06 toaddr 0x9080000 @sdram.bin toaddr 0x900c000 @rom.bin toaddr 0x9000000 @md.bin toaddr 0xe000001 1 0x3c toaddr 0xe080001 1 0x01 toaddr 0x60c0000 1 0xf3
So no chance to run the files in an emulator.

There must be an additional step for linking a ROM cartridge.

One last question: the GNUSIERA example obviously uses srec format and converts this to binary.

Although I link with sh-coff-gcc almost exactly like with Saturn(of course other link script),

the file rom.coff seems to be in srec format, not coff.

I found it out when I tried to use sh-coff-objcopy instead of the GNUSIERA sretobin.exe and it said the format is unrecognized.

So I compared rom.coff with sl.coff from saturn demos and the format really is not comparable.

So how could I accidently link a srec file with sh-coff-gcc?

Oh, my bottom hurts. Think the working 32X cartridge gets delayed to some other day.

I would appreciate your help.

    Hellmut Dec 1, 2004 
Joseph Norman (or dev ster) does have a working c compiler for the 32x. He compiled the sh-elf-gcc and m68k-elf-gcc toolchain to windows. He's going to make a big release of it later when he gets all the libraries done. It's pretty cool, you only need two source files, one for the 68k cpu, and the other for the sh2. The master and slave both run on the same source code, so parallel processing is easy he said. With the linker script he has, it links all the object files together including the 68k and sh2 source files into a rom binary without any tools. Not everything is complete, but you could probably email joe and he can send you the compiler and scripts to get you started with C.

He also has a BASIC compiler too that can create 32x rom files. The only downfall of basic is that it only compiles for 68k, not sh2, so all accesses to the 32x hardware have to be done using the sh2's as a coprocessor. The sh2 coprocessor is built using c source code, but when he releases a new version of the basic compiler, he'll already have a coprocessor source ready to use.

I go to the same university as joe, so i'll talk to him later. the guy's a genius , his website is crap, as in he only has like 5% of the work he's done

    fonzievoltonov Dec 1, 2004 
For the WinXp compatible snasmsh2 and 68k just go @ walmarsx devster page, there is a link on them i think.

"I go to the same university as joe"

Héhé... Just imagine if all the sega dev guys were on the same university Woooo!.

    RockinB Dec 2, 2004 

  
Originally posted by fonzievoltonov+Wed, 2004-12-01 @ 11:13 PM--><div class='quotetop'>QUOTE(fonzievoltonov @ Wed, 2004-12-01 @ 11:13 PM)</div><div class='quotemain'>For the WinXp compatible snasmsh2 and 68k just go @ walmarsx devster page, there is a link on them i think.

[post=124840]Quoted post[/post]
[/b]



Hmmm..like I said, the linked snashmsh2 there isn't working on my WinXP . Maybe I should use some DOS operanting system, like freedos for using sn tools.

I would really like to see if it works when I include my created 32X SH2 binary with WalMarsX.

<!--QuoteBegin-H
ellmut@Wed, 2004-12-01 @ 11:00 PM

Joseph Norman (or dev ster) does have a working c compiler for the 32x. He compiled the sh-elf-gcc and m68k-elf-gcc toolchain to windows. He's going to make a big release of it later when he gets all the libraries done. [post=124839]Quoted post[/post]
[/quote]

Nice to know that DevSter is going to release a GCC solution for SH2. I think I don't need an elf toolchain, when I got a coff toolchain already installed. The linking script instead is the missing thing for me.

And concerning my last question..I think the linker script that I used defined srec output format, so I produced srec format files, regardless if I used sh-coff-ld or sh-coff gcc for linking.