mark r rivet wrote:
> On Tue, 08 Apr 2008 02:32:13 GMT, Frank Kotler <spamtrap@[EMAIL PROTECTED]
>
> wrote:
>
>> mark r rivet wrote:
>>> I'm new to assembly programming except for z80 coarse I took in the
>>> 80's. So I downloaded: Nasm, Nasmide, Alink and have the book
>>> "Assembly Language step by step with Dos and Linux". Is this good or
>>> do I need something else.
> Or start off "Step by Step" and see where it takes you!
>> Best,
>> Frank
>
>
> Thanks alot Frank. Let me explain the reason for my new interest in
> assembly. I have been running this really old dos screen saver called
> "Dazzle"
Ah! We've "spoken" before on the Nasm forum!
> you can find it on the net by searching for Dazzle50.zip.
Yup, okay, got it, and between boots for "other purposes", I took a
quick look. Pretty nice, alright! I didn't investigate all of its
possibilities - there seem to be many. I've seen a lot of "demos" and
"screensavers", some "equally" impressive, perhaps. Seems "worth
preserving".
> I
> have run this most amazing program since the days of the 286, 1980 or
> so.Anyway 20 years later I am still amazed when I look at it. I need
> to know what makes it tick. I don't have the source code, so I want to
> disassemble the .exe and study it. I have the disassembler IDA. it
> disassembled nicely.
Really? As you've discussed, this would be illegal (which bothers me not
at all). Also possibly unethical, which would bother me more. The guy
seems to have really put his heart into it. Also, it's probably the hard
way...
However, if you're interested in "studying" the code, rather than
"stealing" it... in "honoring" him rather than "ripping him off"... I
don't see any problem with that. Still probably the hard way...
> Now I just need a crash course in assembly.
Oh, we can show ya how to make your assembly crash!!! :)
> But
> from what Ican gather from the disassembly, it's a sixteen bit
> program.
Yeah... It's possible to use some 32-bit instructions in 16-bit code,
also possible to use a "dos extender" to use 32-bit code from dos. But
it's kinda old for that... if you've run it on a 286, it's 16-bit.
> It would make me very happy to understand this code and ****t
> it to 32bit and help to immortalize this freaking great code. Maybe
> you could download this program and give me some help with this. One
> way or another, I have to understand this code. I just have to!
Okay... from your latest post, you understand that disassembling the
code may not be the best way to do this. At least not at first. Probably
start with some simple graphics demos first - something we *do* have
source code for... maybe try ****ting a 16-bit example to 32-bit. As
you'll see, the "bitness" isn't much of a problem (32-bit code is
*easier* in many ways), but we're dealing with a different OS and *have*
to do things differently. This can be a blessing or a curse, or both...
I don't have many graphics examples for Windows - a couple. A few more
for dos - nothing as impressive as dazzle, but may have some ideas on
how dazzle might do it.
Besides being a skilled (probably determined, too) programmer, the
author of dazzle is artistic. It's one thing to know how to alter the
palette, another thing to chose pleasing colors. One thing to know how
to do fades and pans and wipes, another thing to string 'em together
into a fluid, pleasing whole. I can't help you with the artistic part...
if you haven't got it, you may *have* to copy dazzle! :)
This probably isn't a good "first" one to work with. As I recall, I
found it "impressive" (very different from dazzle)... but it's obsessed
with being short (256 bytes, IIRC), not "clear". I just happened to
remember the name of this one. I'm a little "booted out" right now, but
when I get to it, I'll try out a few and see if I can find something
that'll "work up to" something vaguely "dazzle-like".
I don't know who originally wrote this. Just something I found on the
web. Presumably the winner - an entry, at least - (I'd vote for it) in
some "demo contest". I think it'll run in a dos-box under Windows... try
it and see...
Best,
Frank
; from flashdaddee.com
; nasm -f bin -o osk.com osk.asm
[org 100h]
[segment .text]
SCREEN equ 160
PIXBUF equ 204h
mov al,13h
int 10h
; set mode 13h - 320 * 200 * 256
push word 0A000h
pop es
; es is video memory
mov ax,cs
add ah,10h
; short way to add ax, 1000h get above our code
mov fs,ax
; fs is a buffer above our program - hopefully, dos
; isn't using it :)
xor cx,cx
; zero loop counter - loop 64k times
; set palette colors - the default ones suffer
PAL1: mov dx,3C8h
; PEL (write) address register
; this tells us which color we're setting
mov ax,cx
out dx,al
; out to the ****t
inc dx
; 3C9h is the PEL data register
sar al,1
js PAL2
out dx,al
; set red component
mul al
shr ax,6
out dx,al
; set green component
PAL2: mov al,0
out dx,al
; set blue if we jumped, red if we didn't?
jns PAL3
; flag set by "shr ax, 6"?
sub al,cl
shr al,1
out dx,al
; set ??? green?
shr al,1
out dx,al
; set ??? blue?
PAL3: mov bx,cx
mov [fs:bx],bl
; store in our buffer
loop PAL1
; this is way too many loops to set palette colors, and
; we're not using all that buffer(?)
; cx is zero from loop above...
TEX: mov bx,cx
add ax,cx
rol ax,cl
mov dh,al
sar dh,5
adc dl,dh
adc dl,[fs:bx+255]
shr dl,1
mov [fs:bx],dl
not bh
mov [fs:bx],dl
loop TEX
fninit
fldz
MAIN: add bh,8
mov di,PIXBUF
fadd dword [byte di-PIXBUF+TEXUV-4]
push di
mov dx,-80
TUBEY: mov bp,-160
TUBEX: mov si,TEXUV
fild word [byte si-TEXUV+EYE]
mov [si],bp
fild word [si]
mov [si],dx
fild word [si]
mov cl,2
ROTATE: fld st3
fsincos
fld st2
fmul st0,st1
fld st4
fmul st0,st3
fsubp st1,st0
fxch st0,st3
fmulp st2,st0
fmulp st3,st0
faddp st2,st0
fxch st0,st2
loop ROTATE
fld st1
fmul st0,st0
fld st1
fmul st0,st0
faddp st1,st0
fsqrt
fdivp st3,st0
fpatan
fimul word [si-4]
fistp word [si]
fimul word [si-4]
fistp word [si+1]
mov si,[si]
lea ax,[bx+si]
add al,ah
and al,64
mov al,-5
jz STORE
shl si,2
lea ax,[bx+si]
sub al,ah
mov al,-16
jns STORE
shl si,1
mov al,-48
STORE add al,[fs:bx+si]
add [di],al
inc di
inc bp
cmp bp,160
EYE equ $-2
jnz TUBEX
inc dx
cmp dx,byte 80
jnz TUBEY
pop si
mov di,(100-SCREEN/2)*320
mov ch,(SCREEN/2)*320/256
rep movsw
;mov ah, 0
;int 16h
mov ch,SCREEN*320/256
BLUR dec si
sar byte [si],2
loop BLUR
;mov ah, 0
;int 16h
in al,60h
cbw
dec ax
jnz near MAIN
mov al,03h
int 10h
db 41,0,0C3h,3Ch
TEXUV db 0FFh, 0FFh, 0FFh, 0FFh ;"xxxx" ;"baze"
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