Well it mostly works now.  But did we ever have the biggest fun with the sound and SVGA.

So [HCI]Mara’akate integrated all the Q1 sound code, got it to compile, but nothing not a peep from the sound card.  While I was busy trashing the video code, he spent way too much time on the audio, and then for the heck of it I thought I’d look at the code, although I’m really stabbing in the dark when it comes to audio.  Imagine my surprise when I compiled the code, and ran it and got the sound blasting at full volume!  It turns out that I had my audio set to ‘high quality’ in the client, while he had his set to ‘low quality’.  What it does is govern the frequency between 11Khz and 22Khz.  And if you get this wrong you get *NO* audio. OOPS.  At least it was one of those feeling vindicated moments that his efforts for sound really did work.

Now with audio, it was my time to hurry up and get the video going.  I had basic VGA working so I figured I didn’t want to spend a lot of time on this, so I was going to go with the VESA 2.0 linear frame buffer.  Well this once more again proved to be a bit more involved as the only way I really have to test is emulation via DOSBox and Qemu.  And naturally both of them worked fine, but when [HCI]Mara’akate ran it on his real DOS Box (with GUS of course) it crashed wonderfully.

Now I had taken the VESA init code from Quake 1 to build a table of what 8bit modes are supported, and used the VESA code to switch, along with drawing to the buffer with a simple memcpy.  And we got nothing but crashes.

After looking more around, I found that you had to add 0x4000 to the VESA mode you want if you wanted to access it’s LFB.  Did that work? No still crashed.

Later in the adventure we noticed to get proper access you had enable ‘near pointer acess’ with a call to :

__djgpp_nearptr_enable();

So naturally I would disable it when I’m done, making the call look like this:

__djgpp_nearptr_enable();
memcpy(vid_resolutions[whatmodearewe].address+__djgpp_conventional_base,vid.buffer,(vid.height*vid.width));
__djgpp_nearptr_disable();

Right?

WRONG. Oh so WRONG.  Well OK technically it did work, but if sound is enabled (and why wouldn’t it be?) it would immediately crash with an error in the DMA code.  We ended up wasting over a day trying to figure this one out until I just said screw it, let’s never dsiable the nearpointer, leave it unprotected.  Naturally that actually worked.  The hint is in map_in_conventional_memory, where __djgpp_nearptr_enable(); is called, but of course there is no calls to __djgpp_nearptr_disable();  I’ve thought about going back through the source to ‘clean’ it up to make it lock and unlock memory as needed, but this is 2015 not 1997 so good enough is well, good enough.

So now with VESA and Sound, I thought this would be a great time to tackle the dynamic loading of gamex86.  We will have to re-compile whatever gamex86 DLLs are out there as of course DOS is DOS.  The HX DOS guy Japheth seems to have died, as his site and all the info on that extender seems to have mostly vanished.  I have an old copy, but I never could make it call DOS stuff if you had WIN32 stuff going on.  And if he’s really dead it’s too late to ask him.

Ages ago I remembered this DLL support for DJGPP called DLM, so I thought I’d give that a try.  I was able to take our ‘null’ version of Quake II, and get it to where it can load and unload the gamex86.dlm at will.  So I figured this was going to be an easy win, right?

Wrong again.  Once I started to put in the MS-DOS specific code I got this fun crash:

DLM -> Exiting due to signal SIGSEGV at
0x0014f59d SYM: _dos_lockmem+0x9 DLM: q2.exe [0xf5000]
possibly because of undefined reference to symbol ‘___djgpp_base_address’

DLM call frame traceback :
0x0014dcaf SYM: _Sys_PageInProgram+0x37 DLM: q2.exe [0xf5000]
0x0014e1c4 SYM: _main+0x18 DLM: q2.exe [0xf5000]
0x0000774e
0x00008b6e

So apparently it doesn’t export (or import) djgpp stuff like the base address calculations so we can’t do direct memory access, which means no video and no sound.  Ouch.  I’ll have to hit the lists to see about support.  I don’t like the DXE’s because they cannot be unloaded, so that isn’t much good.  And of course things like the JVM inside of gamex86.dll is right out as JAVA inside of MS-DOS? in 64MB of RAM? Dream on.

So for now, the gamex86.dll is statically linked into the executable.  You are restricted to vanilla gameplay for now.

As an added bonus, I used Rufus 2.2, to setup a bootable MS-DOS USB stick, slapped everything onto there, and booted up on my Xeon, and it works!

Quake II running on MS-DOS

Now as a super bonus,  [HCI]Mara’akate went above and beyond by adding in a bunch of fixes, and updates from 3.24 and varous stuff from Knightmare.  And then the best part is integrating libogg, so it can now play the ogg sound track!  Really, just place the ogg files in the baseq2\music directory and away you go!

For those who care the bitbucket of the project is here, and binaries are here.

**UPDATE**

For anyone who is interested, I’ve updated the binaries, to include the latest version with built in quakespy technology!  Run an /slist2 and get a list of servers!

/slist2 in action!

For the more adventurous trying to build from source, we are using GCC 2.95.3 and DJGPP 2.04.  All of the sub libraries that you need to build are already pre-compiled in source drop.

At this point the ‘alpha 2’ version contains:

• VGA
• SVGA
• Mouse
• Keyboard
• SoundBlaster and Gravis UltraSound Family
• CD-ROM music
• OGG music
• Networking (You need a packet driver)

Installing the packet driver will require a driver from the crynwr project.  You can find a description of some of the drivers here.  Sadly for new cards I think we are left in the dark.

I’ve also compiled a ‘server’ for Linux based on the code, and put it online @ 87.117.247.11:27910

Continued in pt4, and part 5.

(In this series, I’m going to go over the process of porting Quake II to MS-DOS.  Now of course the question will pop up why? And the answer is simple enough, after [HCI]Mara’akate added in gamespy support, something was noticeably off, and that is fewer and fewer people are playing Quake 1 these days.  So what to do?

Well apparently Quake II has an active following, so it’s time to move our creeky but favorite OS, MS-DOS into the Quake II Arena!

So the first thing to do is to grab a copy of the GPL source to Quake 2, along with a copy of the game, and get started on making a ‘null’ version of the game.  Null versions of the game have no graphical output, no sound, and ‘function’ at a very basic level.  It’s something to strive for as a first base in hitting that home run of a functional port.  Thankfully iD wrote really portable and modular software.  Unfortunately they tended to let their ports drift as they were writing the engine so the null code doesn’t actually work out of the box.  And the project makfiles leave a little to be desired for me, as they have a bunch of i386/Dec Alpha magic which doesn’t leave much in the room for weird ports like MS-DOS.

Now I should mention that before I’d gotten started the first thing I decided that like QuakeWorld for MS-DOS (and OS/2) I would use GCC as it is a known working compiler out of the box.  If you can, don’t fight so many battles of unknowns at once.  Another thing is that I am going to cross compile from OS X and test with DOSBox.  Of course you may want to use something else, and I know my tastes drift, but for now this is what I’m using. I’m using my old OSX to DJGPP cross compiler with GCC 2.95.3, which serves me well.

So the first thing was to compile and run the null version with native tools on OS X.  After a bit of struggle I got here:

$ ./q2
Added packfile ./baseq2/pak0.pak (3307 files)
Added packfile ./baseq2/pak1.pak (279 files)
Added packfile ./baseq2/pak2.pak (2 files)
Console initialized.
Sys_Error: ref_soft::R_BeginFrame() – catastrophic mode change failure

Well that’s great, how to figure this one out?

One thing I did to make it easier to work with the flow of Quake is to make the Sys_Error procedure contain a divide by zero.  Now why would I purposely put a divide by zero in the code?  Simple it lets me back trace the code when Quake catches it’s own faults so I can see what went wrong where, vs what would look like a clean exit.  From my example:

(lldb) bt
* thread #1: tid = 0xf14f9, 0x000c0853 q2`Sys_Error(error=0x000c17d4) + 98 at sys_null.c:28, queue = ‘com.apple.main-thread’, stop reason = EXC_ARITHMETIC (code=EXC_I386_DIV, subcode=0x0)
* frame #0: 0x000c0853 q2`Sys_Error(error=0x000c17d4) + 98 at sys_null.c:28
frame #1: 0x0003a0cb q2`Com_Error(code=0, fmt=0x000c17d4) + 368 at common.c:215
frame #2: 0x000c0523 q2`VID_Error(err_level=0, fmt=0x000cc8a8) + 81 at vid_null.c:45
frame #3: 0x000a6d38 q2`R_BeginFrame(camera_separation=0) + 592 at r_main.c:1145
frame #4: 0x000a4cfc q2`R_Init(hInstance=0x00000000, wndProc=0x00000000) + 276 at r_main.c:333
frame #5: 0x000c0740 q2`VID_Init + 362 at vid_null.c:122
frame #6: 0x00007900 q2`CL_Init + 55 at cl_main.c:1795
frame #7: 0x0003c2cb q2`Qcommon_Init(argc=1, argv=0xbffffc40) + 754 at common.c:1469
frame #8: 0x000c09ac q2`main(argc=1, argv=0xbffffc40) + 24 at sys_null.c:128
frame #9: 0x000019ad q2`_start + 212
frame #10: 0x000018d8 q2`start + 40
(lldb)

Now I know that R_BeginFrame was where the error was occurring, and looking at the code:

if ( ( err = SWimp_SetMode( &vid.width, &vid.height, sw_mode->value, vid_fullscreen->value ) ) == rserr_ok )
{
…
else
{
ri.Sys_Error( ERR_FATAL, “ref_soft::R_BeginFrame() – catastrophic mode change failure\n” );
}

We can see that the vid.width/vid.height aren’t being setup correctly.  Turns out there was a bunch more work to be done setting up vid_null!

After looking closer at the files, I notice as I’m stitching them together is that Quake II relies on DLL’s as part of it’s base functionality.  I drifted out of Quake after Quake 1, so I never played II before.  So I didn’t know this.  Obviously DJGPP doesn’t support DLL’s that can be loaded and un-loaded at will (Yes I know about DXE’s, but as the FAQ states, they cannot be un-loaded.  And I’m not going to fight DJGPP’s LIBC).  So looking further in the source, I saw these fun defines:

-DREF_HARD_LINKED -DGAME_HARD_LINKED

So at one point there was support for ‘hard linking’ in the ‘REF’ video driver, and the ‘game’ logic driver.  But it did kind of drift out of the code.  But looking at the Win32 version I could see that putting this functionality back in should be easy.  And to be honest if I learned any lesson from this, is that I should have been pulling the Win32 version apart by injecting null into it until it ran as a null platform, then use that as the basis.  Lesson learned.  Always start with a known good!  Quake II was built with Visual C++ 6, but I only have Visual C++ 4.2 installed on Crossover.  Yes I know again this is me being difficult.  But it didn’t take much time to get a simple project that has two DLL’s and a Win32 exe running.  Then I took on the ‘ref’ video driver and got that linking inside of the main EXE.  Now with one DLL ‘eliminated’ it was time to work on the game dll.

The game DLL posed the biggest challenge because it passes a reference to internal functions to it, and exports various functions back to the game engine.  So I ended up altering the engine to not call the game import/export directly but setting it up myself.  The hardest thing was that I couldn’t pull in the game header file, but rather I had to copy the prototypes myself.  Another interesting thing with the way Quake II works is that the game dll has to be able to be unloaded and loaded at will.  It wasn’t hard to simulate this, but I wasn’t expecting it.  Again this is probably because I never really played Quake II.

Now that I had Quake II building without DLL’s I could then take the next step of removing all the IO and re-replacing it with the null code, and now I had something that looked like it was doing something.

Added packfile ./baseq2/pak0.pak (3307 files)
Added packfile ./baseq2/pak1.pak (279 files)
Added packfile ./baseq2/pak2.pak (2 files)
execing default.cfg
execing config.cfg
NULLsock Initialized
Console initialized.
768k surface cache
ref_soft version: SOFT 0.01
——- sound initialization ——-
Sys_FindFirst [./baseq2/autoexec.cfg]: UNIMPLEMENTED!
==== InitGame ====
——- Server Initialization ——-
0 entities inhibited
0 teams with 0 entities
————————————-
====== Quake2 Initialized ======
loopback: client_connect
==== ShutdownGame ====
Sys_Error: Draw_Pic: bad coordinates

This turns out because I didn’t allocate the screen properly.  Looking at the code:

if ((x < 0) || (x + w > vid.width) ||
(y + h > vid.height))
{
ri.Sys_Error (ERR_FATAL,”Draw_Pic: bad coordinates”);
}

We can see it pretty plainly.

Now since we were going somewhere I started to write some MS-DOS code, and switch out of the null set of mind!

First a simple VGA mode 13 setup which gives us 320×200 resolution with 256 available colours.  And for good measure I did a simple VGA palette setup that I knew worked from a prior program.  Next we just blit our buffer onto the screen, and we get this:

Quake II on MS-DOS first screen

Which is exciting and disappointing at the same time.  I then took the palette code from DOS Quake, and got something just as ugly.  I tried the code from OS/2. Same thing.  I tried all kinds of things and was going nowhere.

At this point Mara’akate added in the Linux clock code, and now we had this!

Quake II with a bad palette

It wasn’t until much more digging around I saw some 320×240 screen setups that I realized there was something wrong there, and then I saw this gem in the linux port’s code:

/*
** SWimp_SetPalette
**
** System specific palette setting routine. A NULL palette means
** to use the existing palette. The palette is expected to be in
** a padded 4-byte xRGB format.
*/

In traditional VGA palette setups it’s 768 bytes that needs to be read/and pushed to the card.  I even checked Quake 1 is 768 bytes, but now in Quake II, it’s 1024 bytes!  OOPS!  Sometimes (ok a lot of times) you really need to check other ports or a ‘known good’ to see how they did things.

Quake II running on MS-DOS!

Pretty awesome!

So where to go from here? Obviously things like better keyboard input, the mouse, sound and networking need to be done.

Continued in pt2, pt3, pt4, and part5.