ASM Community

Hi, folks!
Just finished (i.e. ran out of ideas for improvement) my chess demo - Win32, OpenGL, 1.5 KB (!).
Some stats: 843 lines of asm; sizeof(data) = 755; 2.25 bytes / instruction on average.
Grab it at http://www.stud.uni-karlsruhe.de/~urkt/ (bottom of page).

While I'm at it :) - anyone interested in an article about / exchanging tips on optimizing for size?

Jan

Well, it brought down Windows XP to the blue screen - haven't seen it in a long time. :) The code looks impressive - wish I had more time to spend on it. Good to see byte shaving still in style. :)

worked fine for me on winxp.... maybe i didnt' play long enough?

Scanning the memory of the system dlls is better than using fixed values 8)

See: http://www.programmingjournal.com/issue4/art3/index.htm

bitRAKE: Thanks.
I don't see anything suspicious; why should it work on BubbaFate's system and not yours? :confused: Usual question: do you have the latest drivers? BTW, anyone know how to detect this a) without too much effort b) in a somewhat portable fashion?

Hey bazik, good link!
First a note on the article: "There is another problem for WinNT/Win2K (at least proven for Win2K and guessed for WinNT) [...] that those operating systems don't run EXE files that have no import table". This is because thread startup code is in kernel32 => kernel32 needs to be loaded (pretty much any import will do, since they all reference kernel32).

What the guy is doing is basically GetProcAddress; in my case, regular imports would probably be smaller (there was a bit of space left in the header for the DLL strings).
Another alternative (from a couple versions back :)): grab the necessary functions from opengl32's IAT.

In case anyone's interested, here it is:

; copy glu32 imports to API table

	mov		esi, data			; esi -> import from glu32

	mov		edi, bss

	mov		ebp, edi

	lodsd						; eax -> glu32 func

	stosd

	movsd



; copy funcs from opengl32 import table

	mov		ax, 0x1080			; eax -> glu32 import tbl + 0x80

	mov		edx, [eax]			; edx -> ogl32 func

	mov		dx, 0x1000			; edx -> ogl32 import tbl

	lodsd						; eax = 0

	mov		cl, num_funcs

.1:	lodsb						; offset/4 of desired func in IAT

	mov		eax, [edx+eax*4]

	stosd

	xor		eax, eax

	loop		.1

	mov		dh, 0				; edx -> ogl32 dll

I switched to fixed offsets when I realized that this method is no less system dependent ;)
Anyway, I need the 'make' step to fixup the opengl32 ordinals (WinXP opengl32 lacks DllInitialize).

natas - Thanks! :) Added to my rather lengthy to-do list...

Where do you get this information from? your knowledge doesnt come from
just reading plain assembly tutorials/books? I would be interested in some
links to any reading material you may know of. ( ;) )

... Me dont care about the rules, and decided to write stuff that could potentially shut the board down...

oh yeah *sigh*

Me realize this is against the rulez and still add more forbidden content, and chuckle with natas.