OSDev.org

The Place to Start for Operating System Developers
https://f.osdev.org/

The Third 512-byte OS Contest!

https://f.osdev.org/viewtopic.php?t=20006

Page 5 of 5

Re: The Third 512-byte OS Contest!

Posted: Mon Jun 01, 2009 4:42 pm
by Masterkiller
Coddy wrote:well, when I disassembled it I got a total of 33 lines of ??? so I am guessing that meens it does not know :?
It seems the code is 0xF5 (245) bytes. The rest are strings and probably the melody itself :) Quite impressive!
P.S. He sets ES to 0, not using it as 0, then sets it to 0xB800 for video memory. Suppressing MOV ES, ax where ax=0 will free 2 more bytes :D

Code: Select all

seg000:0000 ;
seg000:0000 ; ã=========================================================================¬
seg000:0000 ; ¦     This file is generated by The Interactive Disassembler (IDA)        ¦
seg000:0000 ; ¦     Copyright (c) 2006 by DataRescue sa/nv, <[email protected]>        ¦
seg000:0000 ; ¦                      Licensed to: Freeware version                      ¦
seg000:0000 ; L=========================================================================-
seg000:0000 ;
seg000:0000 ; ---------------------------------------------------------------------------
seg000:0000 ; File Name   : C:\512OS\1.bin
seg000:0000 ; Format      : Binary file
seg000:0000 ; Base Address: 0000h Range: 0000h - 0200h Loaded length: 0200h
seg000:0000
seg000:0000                 .686p
seg000:0000                 .mmx
seg000:0000                 .model flat
seg000:0000
seg000:0000 ; ===========================================================================
seg000:0000
seg000:0000 ; Segment type: Regular
seg000:0000 seg000          segment byte public '' use16
seg000:0000                 assume cs:seg000
seg000:0000                 assume es:nothing, ss:nothing, ds:nothing, fs:nothing, gs:nothing
seg000:0000                 xor     ax, ax
seg000:0002                 mov     ds, ax
seg000:0004                 mov     es, ax
seg000:0006                 mov     ss, ax
seg000:0008                 mov     sp, 7C00h
seg000:000B                 mov     di, 0FC00h
seg000:000E                 stosd
seg000:0010                 mov     ax, 0B800h
seg000:0013                 mov     es, ax
seg000:0015                 assume es:nothing
seg000:0015                 mov     ax, 3
seg000:0018                 int     10h             ; - VIDEO - SET VIDEO MODE
seg000:0018                                         ; AL = mode
seg000:001A                 inc     ah
seg000:001C                 mov     cx, 2000h
seg000:001F                 int     10h             ; - VIDEO - SET CURSOR CHARACTERISTICS
seg000:001F                                         ; CH bits 0-4 = start line for cursor in character cell
seg000:001F                                         ; bits 5-6 = blink attribute
seg000:001F                                         ; CL bits 0-4 = end line for cursor in character cell
seg000:0021                 mov     al, 0B6h ; '¦'
seg000:0023                 out     43h, al         ; Timer 8253-5 (AT: 8254.2).
seg000:0025                 mov     word ptr ds:0FC04h, 7D0Dh
seg000:002B                 mov     si, 7D26h
seg000:002E                 xor     edi, edi
seg000:0031                 jmp     short loc_AF
seg000:0033 ; ---------------------------------------------------------------------------
seg000:0033
seg000:0033 loc_33:                                 ; CODE XREF: seg000:00D1j
seg000:0033                 movzx   edi, al
seg000:0037                 and     al, 0Fh
seg000:0039                 and     di, 0F0h
seg000:003D                 shl     al, 1
seg000:003F                 shr     di, 3           ; DATA XREF: seg000:0018r
seg000:003F                                         ; seg000:001Fr
seg000:0042                 push    edi
seg000:0044                 movzx   bp, al
seg000:0047                 mov     bx, [bp+7D16h]
seg000:004B                 mov     al, bl
seg000:004D                 out     42h, al         ; Timer 8253-5 (AT: 8254.2).
seg000:004F                 mov     al, bh
seg000:0051                 out     42h, al         ; Timer 8253-5 (AT: 8254.2).
seg000:0053                 in      al, 61h         ; PC/XT PPI port B bits:
seg000:0053                                         ; 0: Tmr 2 gate =T= OR 03H=spkr ON
seg000:0053                                         ; 1: Tmr 2 data =-  AND 0fcH=spkr OFF
seg000:0053                                         ; 3: 1=read high switches
seg000:0053                                         ; 4: 0=enable RAM parity checking
seg000:0053                                         ; 5: 0=enable I/O channel check
seg000:0053                                         ; 6: 0=hold keyboard clock low
seg000:0053                                         ; 7: 0=enable kbrd
seg000:0055                 or      al, 3
seg000:0057                 out     61h, al         ; PC/XT PPI port B bits:
seg000:0057                                         ; 0: Tmr 2 gate =T= OR 03H=spkr ON
seg000:0057                                         ; 1: Tmr 2 data =-  AND 0fcH=spkr OFF
seg000:0057                                         ; 3: 1=read high switches
seg000:0057                                         ; 4: 0=enable RAM parity checking
seg000:0057                                         ; 5: 0=enable I/O channel check
seg000:0057                                         ; 6: 0=hold keyboard clock low
seg000:0057                                         ; 7: 0=enable kbrd
seg000:0059                 xor     di, di
seg000:005B                 mov     cx, 7D0h
seg000:005E                 mov     ax, 0F20h
seg000:0061                 rep stosw
seg000:0063                 mov     ax, bp
seg000:0065                 mov     bl, 0Ah
seg000:0067                 mul     bl              ; DATA XREF: seg000:00B2r
seg000:0069                 mov     di, ax
seg000:006B                 mov     ax, bp
seg000:006D                 shl     ax, 0Bh
seg000:0070                 add     ah, 20h ; ' '
seg000:0073                 mov     al, 20h ; ' '
seg000:0075                 mov     cx, 19h
seg000:0078
seg000:0078 loc_78:                                 ; CODE XREF: seg000:0083j
seg000:0078                 pusha
seg000:0079                 mov     cx, 0Ah
seg000:007C                 rep stosw
seg000:007E                 popa
seg000:007F                 add     di, 0A0h ; 'à'
seg000:0083                 loop    loc_78
seg000:0085                 pusha
seg000:0086                 mov     si, 7CF6h
seg000:0089                 mov     di, 7BAh
seg000:008C                 call    sub_E8
seg000:008F                 mov     si, ds:0FC04h
seg000:0093                 mov     di, 95Ah
seg000:0096                 lodsb
seg000:0097                 xor     ah, ah
seg000:0099                 add     di, ax
seg000:009B                 push    si
seg000:009C                 mov     si, 7D09h
seg000:009F                 call    sub_E8
seg000:00A2                 pop     si
seg000:00A3                 call    sub_E8
seg000:00A6                 mov     si, 7D09h
seg000:00A9                 call    sub_E8
seg000:00AC                 popa
seg000:00AD                 pop     edi
seg000:00AF
seg000:00AF loc_AF:                                 ; CODE XREF: seg000:0031j
seg000:00AF                                         ; seg000:00C7j
seg000:00AF                 xor     eax, eax
seg000:00B2                 int     1Ah             ; CLOCK - GET TIME OF DAY
seg000:00B2                                         ; Return: CX:DX = clock count
seg000:00B2                                         ; AL = 00h if clock was read or written (via AH=0,1) since the previous
seg000:00B2                                         ; midnight
seg000:00B2                                         ; Otherwise, AL > 0
seg000:00B4                 mov     ax, cx
seg000:00B6                 shl     eax, 10h
seg000:00BA                 mov     ax, dx
seg000:00BC                 mov     ebx, eax
seg000:00BF                 sub     eax, ds:0FC00h
seg000:00C4                 cmp     eax, edi
seg000:00C7                 jl      short loc_AF
seg000:00C9                 mov     ds:0FC00h, ebx
seg000:00CE
seg000:00CE loc_CE:                                 ; CODE XREF: seg000:00E1j
seg000:00CE                                         ; seg000:00E6j
seg000:00CE                 lodsb
seg000:00CF                 or      al, al
seg000:00D1                 jnz     loc_33
seg000:00D5                 mov     ds:0FC04h, si
seg000:00D9                 lodsb
seg000:00DA                 or      al, al
seg000:00DC                 jz      short loc_E3
seg000:00DE                 call    sub_E8
seg000:00E1                 jmp     short loc_CE
seg000:00E3 ; ---------------------------------------------------------------------------
seg000:00E3
seg000:00E3 loc_E3:                                 ; CODE XREF: seg000:00DCj
seg000:00E3                 mov     si, 7D35h
seg000:00E6                 jmp     short loc_CE
seg000:00E8
seg000:00E8 ; --------------- S U B R O U T I N E ---------------------------------------
seg000:00E8
seg000:00E8
seg000:00E8 sub_E8          proc near               ; CODE XREF: seg000:008Cp
seg000:00E8                                         ; seg000:009Fp ...
seg000:00E8                 lodsb
seg000:00E9                 or      al, al
seg000:00EB                 jz      short locret_F5
seg000:00ED                 stosb
seg000:00EE                 or      byte ptr es:[di], 0Fh
seg000:00F2                 inc     di
seg000:00F3                 jmp     short sub_E8
seg000:00F5 ; ---------------------------------------------------------------------------
seg000:00F5
seg000:00F5 locret_F5:                              ; CODE XREF: sub_E8+3j
seg000:00F5                 retn
seg000:00F5 sub_E8          endp
seg000:00F5
seg000:00F5 ; ---------------------------------------------------------------------------
seg000:00F6 aYouGotRickroll db 'You Got Rickroll',27h,'d',0
seg000:0109                 dd 200E20h
seg000:010D aDIntro         db 'D(Intro)',0
seg000:0116                 db 0E3h ; ó
seg000:0117                 db  0Bh
seg000:0118                 db  97h ; ×
seg000:0119                 db  0Ah
seg000:011A                 db  6Fh ; o
seg000:011B                 db    9
seg000:011C                 db 0E9h ; ù
seg000:011D                 db    8
seg000:011E                 db 0F0h ; ¨
seg000:011F                 db    7
seg000:0120                 db  12h
seg000:0121                 db    7
seg000:0122                 db 0ADh ; í
seg000:0123                 db    6
seg000:0124                 db 0F1h ; ¸
seg000:0125                 db    5
seg000:0126                 db  83h ; Ã
seg000:0127                 db  84h ; Ä
seg000:0128                 db  60h ; `
seg000:0129                 db  84h ; Ä
seg000:012A                 db  85h ; Å
seg000:012B                 db  17h
seg000:012C                 db  16h
seg000:012D                 db  15h
seg000:012E                 db  14h
seg000:012F                 db  83h ; Ã
seg000:0130                 db  84h ; Ä
seg000:0131                 db  60h ; `
seg000:0132                 db  35h ; 5
seg000:0133                 db  37h ; 7
seg000:0134                 db  85h ; Å
seg000:0135                 db    0
seg000:0136                 db  32h ; 2
seg000:0137 aWeReNoStranger db 'We',27h,'re no strangers to love',0
seg000:0152                 db  31h ; 1
seg000:0153                 db  32h ; 2
seg000:0154                 db  33h ; 3
seg000:0155                 db  33h ; 3
seg000:0156                 db  34h ; 4
seg000:0157                 db  62h ; b
seg000:0158                 db  61h ; a
seg000:0159                 db 0F0h ; ¨
seg000:015A                 db    0
seg000:015B ; a___Verse_
seg000:015B a___Verse___    db '>...(Verse)...',0
seg000:016A                 db  31h ; 1
seg000:016B                 db  31h ; 1
seg000:016C                 db  32h ; 2
seg000:016D                 db  93h ; Ó
seg000:016E                 db  30h ; 0
seg000:016F                 db  67h ; g
seg000:0170                 db  37h ; 7
seg000:0171                 db 0F4h ; ¯
seg000:0172                 db  31h ; 1
seg000:0173                 db  31h ; 1
seg000:0174                 db  32h ; 2
seg000:0175                 db  33h ; 3
seg000:0176                 db  31h ; 1
seg000:0177                 db  33h ; 3
seg000:0178                 db  64h ; d
seg000:0179                 db  32h ; 2
seg000:017A                 db  31h ; 1
seg000:017B                 db 0F0h ; ¨
seg000:017C                 db  31h ; 1
seg000:017D                 db  31h ; 1
seg000:017E                 db  32h ; 2
seg000:017F                 db  33h ; 3
seg000:0180                 db  31h ; 1
seg000:0181                 db  60h ; `
seg000:0182                 db  34h ; 4
seg000:0183                 db  34h ; 4
seg000:0184                 db  34h ; 4
seg000:0185                 db  35h ; 5
seg000:0186                 db 0F4h ; ¯
seg000:0187                 db 0E3h ; ó
seg000:0188                 db  34h ; 4
seg000:0189                 db  35h ; 5
seg000:018A                 db  33h ; 3
seg000:018B                 db  34h ; 4
seg000:018C                 db  34h ; 4
seg000:018D                 db  34h ; 4
seg000:018E                 db  35h ; 5
seg000:018F                 db  64h ; d
seg000:0190                 db 0F0h ; ¨
seg000:0191                 db  31h ; 1
seg000:0192                 db  32h ; 2
seg000:0193                 db  33h ; 3
seg000:0194                 db  61h ; a
seg000:0195                 db  34h ; 4
seg000:0196                 db  35h ; 5
seg000:0197                 db  94h ; Ô
seg000:0198                 db    0
seg000:0199                 db  34h ; 4
seg000:019A aNeverGonnaGive db 'Never gonna give you up',0
seg000:01B2                 db  10h
seg000:01B3                 db  11h
seg000:01B4                 db  13h
seg000:01B5                 db  11h
seg000:01B6                 db  45h ; E
seg000:01B7                 db  45h ; E
seg000:01B8                 db  94h ; Ô
seg000:01B9                 db    0
seg000:01BA ; a___Chorus_
seg000:01BA a___Chorus___   db '>...(Chorus)...',0
seg000:01CA                 db  10h
seg000:01CB                 db  11h
seg000:01CC                 db  13h
seg000:01CD                 db  11h
seg000:01CE                 db  44h ; D
seg000:01CF                 db  44h ; D
seg000:01D0                 db  93h ; Ó
seg000:01D1                 db  10h
seg000:01D2                 db  11h
seg000:01D3                 db  13h
seg000:01D4                 db  11h
seg000:01D5                 db  63h ; c
seg000:01D6                 db  34h ; 4
seg000:01D7                 db  62h ; b
seg000:01D8                 db  60h ; `
seg000:01D9                 db  30h ; 0
seg000:01DA                 db  64h ; d
seg000:01DB                 db 0C3h ; +
seg000:01DC                 db  10h
seg000:01DD                 db  11h
seg000:01DE                 db  13h
seg000:01DF                 db  11h
seg000:01E0                 db  65h ; e
seg000:01E1                 db  35h ; 5
seg000:01E2                 db  94h ; Ô
seg000:01E3                 db  10h
seg000:01E4                 db  11h
seg000:01E5                 db  13h
seg000:01E6                 db  11h
seg000:01E7                 db  67h ; g
seg000:01E8                 db  32h ; 2
seg000:01E9                 db  93h ; Ó
seg000:01EA                 db  10h
seg000:01EB                 db  11h
seg000:01EC                 db  13h
seg000:01ED                 db  11h
seg000:01EE                 db  63h ; c
seg000:01EF                 db  34h ; 4
seg000:01F0                 db 0C2h ; T
seg000:01F1                 db  31h ; 1
seg000:01F2                 db  30h ; 0
seg000:01F3                 db  64h ; d
seg000:01F4                 db 0F3h ; º
seg000:01F5                 db    0
seg000:01F6                 db    0
seg000:01F7                 db    0
seg000:01F8                 db    0
seg000:01F9                 db    0
seg000:01FA                 db    0
seg000:01FB                 db    0
seg000:01FC                 db    0
seg000:01FD                 db    0
seg000:01FE                 dw 0AA55h
seg000:01FE seg000          ends
seg000:01FE
seg000:01FE
seg000:01FE                 end

Re: The Third 512-byte OS Contest!

Posted: Mon Jun 01, 2009 5:04 pm
by Coty
hmm... something tells me I need to get a new disassembler... here is what I got on the first 20 lines when I disassembled it:

Code: Select all

skeq v1,C0
???
mov v14,v12
jmi C00
add v12,BF
scdown 14
mov v6,AB
jmi 88E
rand v0,0B8
scdown 0
rand v13,D10
???
jmi 900
jsr 0CD
jmp 0B0
jmi 6E6
skne v3,C7
scdown 4
add v14,D
Messed up huh? :?

@Zenith: thanks, now my collection is complete :D

Re: The Third 512-byte OS Contest!

Posted: Mon Jun 01, 2009 5:08 pm
by Zenith
Masterkiller wrote:It seems the code is 0xF5 (245) bytes. The rest are strings and probably the melody itself :) Quite impressive!
P.S. He sets ES to 0, not using it as 0, then sets it to 0xB800 for video memory. Suppressing MOV ES, ax where ax=0 will free 2 more bytes :D
Well actually, setting ES to 0 allows me to use stosd instead of something like mov dword [0x00:0xFC00], 0. :wink: (Oh well, I'll check which method takes up less space sometime).

And in case you missed it, I posted the code for my demo right before you posted your disassembly :D.

@Coddy: Whoa! I think you've got a disassembler for a completely different architecture there. (Did some research and it seems to be output for CHIP-8 VM opcodes - back in the good old days... See here and here.)

Re: The Third 512-byte OS Contest!

Posted: Mon Jun 01, 2009 5:20 pm
by Coty
sweet, its pong time 8) beep........beep....beep.beep......beep.....beeeep woo! I lost 8)
Image
I thought that site looked old :P

Re: The Third 512-byte OS Contest!

Posted: Mon Jun 01, 2009 8:17 pm
by Troy Martin
Coddy wrote:hmm... something tells me I need to get a new disassembler... here is what I got on the first 20 lines when I disassembled it:

Code: Select all

<snip>
Messed up huh? :?

@Zenith: thanks, now my collection is complete :D
... that's not an x86 disassembler... what the hell program is that?

EDIT: thanks Zenith.

Re: The Third 512-byte OS Contest!

Posted: Tue Jun 02, 2009 4:46 am
by Dex
Nice code Zenith, you had my vote.
Coddy you can add this "AI pong" to your collection, its only 265 byte.

Code: Select all

; small AI game demo, compile with fasm.
; Original written by Luks, for nasm.
; c:\fasm game.asm game.com
org 0x100
use16
START:

mov     al,0x13
int     0x10

MAIN:
push    word 0x8000
pop     es
push    cs
pop     ds

mov     cx,0xFFFF
mov     al,0
rep     stosb
mov     si,BALLYI
call    PutLine
mov     bx,[si-6]
mov     dx,[si-4]
cmp     dx,195
jb      CMPY
jmp     NEGY
CMPY:
cmp     dx,1
jg      ADDY
NEGY:
neg     word[si]
ADDY:
add     dx,[si]
dec     si
dec     si
cmp     bx,310
jb      CMPX
jmp     NEGX
CMPX:
cmp     bx,6
jg      ADDX
NEGX:
neg     word[si]
ADDX:
add     bx,[si]
sub     si,8
mov     di,dx
imul    di,320
add     di,bx
mov     cl,4
BALL:
mov     [es:di], dword 0x0f0f0f0f
add     di,320
loop    BALL
mov     [si+4],bx
mov     [si+6],dx

; PADS
mov     bp,si
cmp     [si+9],byte 0
je      PAD2
PAD1:
call    PADCHK
jmp     PADS
PAD2:
add     bp,2
call    PADCHK

PADS:
mov     ax,[si]
mov     di,2
call    DRAWPAD
mov     ax,[si+2]
mov     di,314
call    DRAWPAD
push    es
pop     ds
push    word 0xA000
pop     es
mov     cx,32000
xor     si,si
mov     di,si
rep     movsw
mov     ah,0x11
int     0x16
jz      MAIN
mov     ax,0x0003
int     0x10

DRAWPAD:
imul    ax,320
add     di,ax
mov     cx,16
PAD:
mov     [es:di], dword 0x0f0f0f0f
add     di,320
loop    PAD
ret

PADCHK:
cmp     dx,[bp]
jge     PADDOWN
dec     word [bp]
jmp     ENDCHK
PADDOWN:
sub     dx,12
cmp     dx,[bp]
jbe     ENDCHK
inc     word [bp]
ENDCHK:
ret

PutLine:
mov     al,15
mov     di,158
mov     cl,198
@@:
add     di,319
stosb
loop    @b
xor     di,di
call    Hline
xor     dx,dx
xor     di,di
mov     cl,199
Gridlp3:
stosb
add     di,318
stosb
loop    Gridlp3
call    Hline
ret
               
Hline:
mov     al,15
mov     cx,320
rep     stosb
ret

PAD1Y   dw      100
PAD2Y   dw      100
BALLX   dw      160
BALLY   dw      100
BALLXI  dw      -1
BALLYI  dw      -1
I did not write it, i just converted it.

Re: The Third 512-byte OS Contest!

Posted: Tue Jun 02, 2009 6:49 am
by Coty
that cool, hmm... It gives me an inspiration for...... bootible pong :)

Re: The Third 512-byte OS Contest!

Posted: Mon Jun 29, 2009 5:22 am
by a427
Any chances to see a fourth 512-byte asm compo organized ? :roll:

(I managed to successfully miss the first three editions, and hence still have got a potential entry ready and waiting.. grumble..)

Re: The Third 512-byte OS Contest!

Posted: Mon Jun 29, 2009 9:11 am
by earlz
What? I missed it again?

Re: The Third 512-byte OS Contest!

Posted: Mon Jun 29, 2009 9:46 am
by Troy Martin
We're still "discussing" the next one in some other thread somewhere. Not sure when it will pop into existence though.

EDIT: spelling fail.

Re: The Third 512-byte OS Contest!

Posted: Tue Jun 30, 2009 3:54 pm
by Coty
I can't wait, maybe I can finely get a fourth folder on my site directory :D
All times are UTC-06:00
Page 5 of 5

Powered by phpBB® Forum Software © phpBB Limited