Dírojed CGA by CRTC

screenshot added by reenigne on 2014-06-24 09:58:38

platform :	MS-Dos MS-Dos
type :	32b 32b
release date :	june 2014
release party :	Sundown 2014
compo :	oldskool demo
ranked :	3rd
related :	ported from: Dírojed

popularity : 60%

60%

0.81

alltime top: #7575

reenigne [code]

added on the 2014-06-24 09:58:38 by reenigne

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Port from 286+/VGA to 8088/CGA of Dírojed by Řrřola (http://www.pouet.net/prod.php?which=28913) while remaining 32 bytes.

Due to size limitations I had to change the exit key from Esc to Ctrl+Alt+Del, and you get a reboot for free.

DOSBox capture (long version).
Live video from the party (thanks to Deltafire).

More info and greetz in the .nfo.

added on the 2014-06-24 10:05:36 by reenigne

was it port or blatant rip?

added on the 2014-06-24 10:25:05 by g0blinish

Hoi hoi hoi. CGA. 8088. Hoi Hoi Hoi!

rulez added on the 2014-06-24 11:05:50 by Optimus

g0blinish: Compare the codes and decide for yourself! I did start from Řrřola's code but only 1/3 of the instructions remain unchanged. Also the constraints are so tight I would probably have ended up with the same code even if I tried to implement the same algorithm from scratch.

added on the 2014-06-24 11:28:40 by reenigne

Cool, not too many CGA prods around.

rulez added on the 2014-06-24 11:58:02 by Preacher

wow! :)

rulez added on the 2014-06-24 12:13:24 by mad

Cool

rulez added on the 2014-06-24 12:59:04 by bitl

More and more 8088 entries, keep it coming!

rulez added on the 2014-06-24 13:02:35 by Harekiet

It's a classic 32b, and looks good in CGA. I recommend watching on dosbox (or real hardware of course :) btw, since the youtube doesn't do it justice compared to what I saw at the party. The 'dither' pattern was really neat.

rulez added on the 2014-06-24 16:41:33 by psonice

I don't know ... i looked at the codes, and it is basically the same. Changes are of cause due to the different screen mode, but otherwise, same concept, same cellular automaton, even same pseudo random value. The flow is a little different (XCHG) but you lost the "ESC" function. Also, i instantly see a 1 byte improvement ... so what do i do here?

I'll closely thumb it up, for keeping the name of a legend alive, for the approach itself, for the retro spirit, and for yay! CGA ;)

rulez added on the 2014-06-24 17:36:21 by HellMood

nice looking 32b. also looked nice at the stream. so here is my thumbs.

rulez added on the 2014-06-24 17:46:51 by sensenstahl

Well, actually it seems not to difficult to hack the CGA mode into Rrrola's original, while keeping the possibility to quit with "ESC", and also keep the filesize at 32 bytes.

Code:

org  100h         
mov  al,04h      
int  10h          
mov  bh,0xb8		
mov  ds,bx		 
M:
cmp  [bx],cl      
adc  [bx],ah    
imul bx,byte 0xE5 
mov  cl,[bx]     
add  cl,[bx+di]   
add  cl,[bx-81]   
add  cl,[bx+si+63]
dec  bx           
in   al,60h      
dec  ax          
jnz  M           
ret

Tested in DOSBox 0.74 and Virtual Box (MSDOS 6.22)

Download commented source and executable >>here<<

added on the 2014-06-24 19:42:29 by HellMood

mov bh,0xb8 - of course! 3 more and I can put back the Esc functionality... In my defense, I stopped looking for optimizations once I reached 32 bytes.

Yes, it is very derivative of the original Dírojed and I never claimed otherwise. But it is a party hack, and it's about as different from Dírojed as Dírojed is from Lochfrass.

added on the 2014-06-24 19:50:58 by reenigne

HellMood: The original point point of Dírojed CGA was to run on my XT so I can't use that "imul bx,byte 0xe5" instruction. Nice work though!

added on the 2014-06-24 19:53:55 by reenigne

@reengine: I see ;) I'm still very sure escapeable XT code is possible. For example, the "MOV AX ..." opcode is 0xB8 which could be re~used as screen adress. Also, you wouldnt need the complete manhattan neighbourhood for this kind of effect. Just taking and giving inspirations here =)

added on the 2014-06-24 19:58:37 by HellMood

Yeah, if I take just take out the

Code:add cl,[bx+79]

line I can put back the Esc code and keep it in 32 bytes and working on an 8088. I just get diamond shapes growing down instead of oval shapes growing in all directions. Nice idea!

added on the 2014-06-24 20:29:28 by reenigne

nice variation

rulez added on the 2014-06-26 10:27:47 by whizart

Congrats on the 3rd place.

You don't really need the imul - "inc bp, sbb bx,bp" saves 3 bytes and looks similar. See the Kristal source for some Dírojed tweaks.

rulez added on the 2014-06-26 17:14:18 by rrrola

@rrrola: Oh wow, that is some insane and brilliant code! I was wondering the other day if it would be possible to overlap the initialization code with the start of the loop to get save some bytes. This random number generator is great too. As are the "xchg ax,cx; loop", "imul si" and "xlatb" tricks.

This version doesn't work so well on DOSBox though - I think there we just get too many iterations before the enter key is released so there are too many initial seed points. We can fix that (at the cost of turning off the keyboard control) by changing the imul to a mul, getting rid of the cmc and changing

Code:sbb [bx],dh

Code:adc [bx],dh

.

Using these tricks I was able to make a CGA version which spreads in all directions and has a working Esc! I couldn't find an overlapping instruction sequence that worked, but realized that I could load the segment register in 3 bytes using

Code:lds ax,[si-3]

, recycling the 0xb0 opcode from the initial "mov al,4" instruction as the high byte of the segment.

added on the 2014-06-27 16:15:47 by reenigne

Guys, you´re awesome =D

rulez added on the 2014-07-15 02:44:10 by T$