17 byte demo!

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bitshifter

Joined: 04 Dec 2007
Posts: 796
Location: Massachusetts, USA

bitshifter 31 Aug 2008, 08:55

Code:

use16
org 0x100
mov ax,0x13
int 0x10
push word 0xA000
pop es
paint:
adc ax, cx
stosb
loop paint
inc ax
jmp paint

EDIT by DOS386 2014-May-22 : check out http://board.flatassembler.net/topic.php?t=9174 http://board.flatassembler.net/topic.php?t=16699 too

31 Aug 2008, 08:55

Artlav

Joined: 23 Dec 2004
Posts: 188
Location: Moscow, Russia

Artlav 31 Aug 2008, 12:44

Whoa!
Now that is some self-organizing property.

31 Aug 2008, 12:44

bitshifter

Joined: 04 Dec 2007
Posts: 796
Location: Massachusetts, USA

bitshifter 31 Aug 2008, 12:58

Think you can shave a few bytes off it Question

31 Aug 2008, 12:58

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 31 Aug 2008, 14:26

nice!

31 Aug 2008, 14:26

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 31 Aug 2008, 15:43

Well the obvious "mov ax,0x13" > "mov al,0x13" creates a 16-byte executable. But I'm unsure if AX is guaranteed to be zero at entry point though.

31 Aug 2008, 15:43

Goplat

Joined: 15 Sep 2006
Posts: 181

Goplat 31 Aug 2008, 18:49

AL and BL will be 00 if the first FCB filename passed to the program has either no drive letter or a valid drive letter, or FF if it has an invalid drive letter. AH and BH are set the same way, but from the second FCB filename.

command.com sets the FCB filenames according to the command line. So for example, if you start a program as just "program" it will have AX = BX = 0000, but start it as "program Z:file" and it will have AX = BX = 00FF (assuming there is no Z: drive), and start it as "program C:file Z:file" and it will have AX = BX = FF00.

31 Aug 2008, 18:49

Alphonso

Joined: 16 Jan 2007
Posts: 295

Alphonso 31 Aug 2008, 20:56

Well if your willing to be dirty, what about

Code:

use16
org 0x100 
mov al,0x13
int 0x10
les ax,[bx]
paint:
adc ax, cx
stosb
loop paint
inc ax
jmp paint

14bytes. Should work for most people although you will probably lose a few pixels. Also assuming ax=bx=0.

Last edited by Alphonso on 01 Sep 2008, 02:42; edited 1 time in total

31 Aug 2008, 20:56

edfed

Joined: 20 Feb 2006
Posts: 4330
Location: Now

edfed 31 Aug 2008, 21:44

the same, 14 bytes, but moving.

Code:

org 100h
mov al,13h
int 10h
les ax,[bx] 
paint: 
adc ax, cx
stosb 
loop paint 
inc ax
loop paint

[edit], what is very strange is that it will draw perfect circles, into a square dimension."without any sincos".

31 Aug 2008, 21:44

bitshifter

Joined: 04 Dec 2007
Posts: 796
Location: Massachusetts, USA

bitshifter 01 Sep 2008, 01:51

That's pretty cool edfed!

01 Sep 2008, 01:51

Alphonso

Joined: 16 Jan 2007
Posts: 295

Alphonso 01 Sep 2008, 21:47

12 Bytes, but not as nice looking

Code:

org 100h

 mov al,13h
 int 10h
 les ax,[bx]
paint:
 sbb ax,di
 stosb
 inc di
 jmp paint

01 Sep 2008, 21:47

edfed

Joined: 20 Feb 2006
Posts: 4330
Location: Now

edfed 01 Sep 2008, 23:14

Alphonso wrote:

12 Bytes, but not as nice looking

Code:

org 100h

 mov al,13h
 int 10h
 les ax,[bx]
paint:
 sbb ax,di
 stosb
 inc di
 jmp paint

but 12 bytes.
Wink

[edit]

just an idea, but what about an executable format with a " stack & registers" header?
something to assume value to registers and stack, use less memory than the initialisation code. hte routine thats preload the regs is in the os, while file loading.

Code:

format as .prexe
.eax dd 0
.ebx dd 0
.ecx dd 64000
.edx dd 2008
.edi dd 0
.esi dd mainentry
.esp dd 57AC4h
.ebp dd 1000h
.cs dd 1000h
.ds dd 0
.etc etc

.exe is still likt this but it don't have general registers init table.

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01 Sep 2008, 23:14

Madis731

Joined: 25 Sep 2003
Posts: 2139
Location: Estonia

Madis731 02 Sep 2008, 16:18

Anyone care to explain what it does to a person under 64-bit environment. 16-bit isn't my cup of tea (I imagined simulating it in my head).

02 Sep 2008, 16:18

LocoDelAssembly
Your code has a bug

Joined: 06 May 2005
Posts: 4624
Location: Argentina

LocoDelAssembly 02 Sep 2008, 17:33

That person could use DOSBox Wink

02 Sep 2008, 17:33

neville

Joined: 13 Jul 2008
Posts: 507
Location: New Zealand

neville 05 Sep 2008, 07:45

Here's a VESA LFB version of bitshifter's 17-byte demo.

It assumes you're in Flat Real mode because in most VESA Bios's the linear buffer maps to the top few MB of the 4GB address space. It also assumes your Bios supports VESA LFB - no checks. I've added exit code so you can run it in pure DOS without crashing.

Despite the higher resolution, it runs very fast - so the colours look a bit washed out because they're changing so fast.

Code:

;assemble with FASM (66 bytes + 256-byte VESA buffer)
   ORG     0100H
       MOV     AX,4F01H
    MOV     CX,101H 
    MOV     DI,VESABUF
  INT     10H
 MOV     ECX,[DI+28H]    ;save LFB address
   MOV     AX,4F02H
    MOV     BX,4101H        ;linear 640x480x8-bit mode
  INT     10H
 PUSH    0000
        POP     DS
  MOV     EBX,ECX         ;LFB address
PAINT0: XOR ESI,ESI
     XOR     CX,CX
PAINT:     ADC     AX,CX
       MOV     [EBX+ESI],AL    ;write pixel
        INC     ESI
 LOOP    PAINT
       INC     AX
  PUSH    AX
  MOV     AH,1
        INT     16H
 POP     AX
  JNZ     QUIT
        CMP     ESI,50000H      ;>full screen?
   JZ      PAINT0          ; -y, back to top
   JMP     PAINT   
QUIT:   INT     20H
VESABUF:                     ;256 bytes not initialised

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05 Sep 2008, 07:45

asmdude

Joined: 01 Sep 2008
Posts: 2

asmdude 05 Sep 2008, 19:36

What does this do:

Code:

les ax,[bx]

05 Sep 2008, 19:36

Alphonso

Joined: 16 Jan 2007
Posts: 295

Alphonso 05 Sep 2008, 20:05

loads es:ax from memory location [bx]

So if BX=0 this points to DS:0000 which is the start of the PSP for a .com file.

Register AX will get loaded with the first two bytes, normally CD20h

Segment register ES will get loaded with the next two bytes which should be the available memory to DOS in paragraphs (1 paragraph = 16 bytes). This will probably be a little under 640k or A000h, ie 9Fxx.

05 Sep 2008, 20:05

asmdude

Joined: 01 Sep 2008
Posts: 2

asmdude 05 Sep 2008, 20:16

Thanks!

05 Sep 2008, 20:16

neville

Joined: 13 Jul 2008
Posts: 507
Location: New Zealand

neville 05 Sep 2008, 20:46

Can anybody write a paged VESA version of my linear VESA code above in less than 66 bytes? I don't expect it to run faster, just smaller code Exclamation

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FAMOS - the first memory operating system

05 Sep 2008, 20:46

Chewie RFC

Joined: 25 Oct 2008
Posts: 3
Location: California

Chewie RFC 25 Oct 2008, 07:08

Alphonso wrote:

loads es:ax from memory location [bx]

So if BX=0 this points to DS:0000 which is the start of the PSP for a .com file.

Register AX will get loaded with the first two bytes, normally CD20h

Segment register ES will get loaded with the next two bytes which should be the available memory to DOS in paragraphs (1 paragraph = 16 bytes). This will probably be a little under 640k or A000h, ie 9Fxx.

But WHY does this work? VGA RAM starts at A000. The segment 9FFF (or whatever it happens to load) is still part of DOS memory. I can't figure out why this is writing pixels to the screen when ES is not pointed to the video RAM. Any help?

25 Oct 2008, 07:08

DJ Mauretto

Joined: 14 Mar 2007
Posts: 464
Location: Rome,Italy

DJ Mauretto 25 Oct 2008, 08:31

Debug with dos debug and you will understand Smile

First you must to be an Hacker ,then programmer Razz

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25 Oct 2008, 08:31

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