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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
Hi everyone!
It's me again. Here's my code

Code:
        USE16
        ORG 07C00h

        START:
        mov ecx, 0FFh    ; put 0FFh to ecx for loop 

        LOADKERN:        ; loading kernel
        mov dl, cl          ; number in dl is number in ecx now
        mov di, cs  
        mov ds, di        ; loading DAP segment            
        mov di, DAP     ; and offset
        mov ah, 42h     ; function number
        pusha               ; saving registers(because i dont know what int is going to do with them
        int 13h             ; calling INT 13h
        push ax            ; saving error code
        mov al, '2'        ; that just was to indicate where mistake occured(remains of fail handler)
        jnc FAIL           ; jump to FAIL(originally it was fail handler, but now it's non-fail handler
        pop ax             ; put ax back to ax if we didnt jump to FAIL
        AFTERFAIL:      ; just pointer where FAIL must return
        popa                ; taking back all registers
        loop LOADKERN  ; and doing all of this FF times

        AMOUNTOFMEMSCAN:; it has nothing to do with problem
        mov ax, 0E801h
        int 15h
        mov al, '1'
        jc FAIL
        xchg ax, bx
        mov bx, 0FFFFh
        mul bx
        mov di, MAXMEMADDR
        mov [cs:di], eax

        LDSO:
        jmp LDSO

        FAIL:                         ; FAIL, as I said previiously it is non-fail handler
        mov ah, 0eh             ;
        int 10h                     ; putting number in al to screen(remains of fail handler)
        pop ax                     ; taking error code back to ax, so I can see it in debugger(remains of fail handler, but still usefull, only a bit)
        jmp AFTERFAIL   ; back to procedure


        DAP:
        DAP_Size            db 10h                            ;size of packet
        DAP_Res1            db 0                       ; reserved
        DAP_Bytes2Transfer  db 4h  ;amount of sectors that have to be transferred
        DAP_Res2            db 0        ;reserved
        DAP_Buff_Addr       dd 08100000h     ;place where im putting my kernel - 0810h:0000 or 8100h  
        DAP_LBA             dq 0h                   ;lba address of the first sector to read
        times 12 db 0

        MAXMEMADDR dd 0;it has nothing to do with problem too

        times 1954 db 0
        dw 0AA55h      
    


I start it in Virtual Box, and that is what i get(picture)
The code must try all BIOS device numbers, and try to read from each one, and if there is no mistake it goes to FAIL(dont ask), and I guess it finaly found CD-ROM number (F0h in ah when message strikes) but what about this message???


Description:
Filesize: 71.84 KB
Viewed: 913 Time(s)

D'oh.JPG




Last edited by BOTOKILLER on 30 Mar 2011, 10:22; edited 1 time in total
Post 30 Mar 2011, 09:33
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roboman



Joined: 03 Dec 2006
Posts: 122
Location: USA
roboman
>AH = 42h
>DL = drive number
>DS:SI -> disk address packet

So you have FFh as your drive number....
and I'm guessing the >mov di, DAP
should have been: mov si, DAP

>00h BYTE size of packet (10h or 18h)
>01h BYTE reserved (0)
>02h WORD number of blocks to transfer (max 007Fh for Phoenix EDD)
>04h DWORD -> transfer buffer
>08h QWORD starting absolute block number
(for non-LBA devices, compute as
(Cylinder*NumHeads + SelectedHead) * SectorPerTrack +
SelectedSector - 1
>10h QWORD (EDD-3.0, optional) 64-bit flat address of transfer buffer;
used if DWORD at 04h is FFFFh:FFFFh


DAP_Size db 10h
DAP_Res1 db 0
DAP_Bytes2Transfer db 4h
DAP_Res2 db 0
DAP_Buff_Addr dd 08100000h
DAP_LBA dq 0h

Um, the sizes don't match. Comments as to what you are trying to do might help. Guessing that's a boot sector and you are taking a shot at loading something, from some drive, to some where, but am a bit lost as to exactly what you are shooting for.
Post 30 Mar 2011, 10:01
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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
code comments - done(much of old useless code, which is now no needed there)
about DAP - http://www.t13.org/Documents/UploadedDocuments/project/d1386r5-EDD.pdf - these are specs, page 9 - I filled it accordingly to this table
any other ideas???
Post 30 Mar 2011, 10:27
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roboman



Joined: 03 Dec 2006
Posts: 122
Location: USA
roboman
>AH - 42h
>DL - BIOS device number
>DS:SI - Device address packet

That part agrees with Ralf Brown's Interrupt List. So you are starting at the highest possible device and just working your way down, trying to load the boot sector

mov ds, di ; loading DAP segment
mov di, DAP ; and offset

oopps, the offset should have been put in si. Don't see si in the program, so it's a guess as to what chunk of memory it's reading as a DAP table.

So the software just starts with the last possible device and counts down loading any thing found in the first 4 sectors into the same location it did with the last device, then goes into an endless loop?
Or 400h sectors get copied, depending on whos docs are right.

Hoping to see each drives lights come on as a test? Don't know why the error message, I checked several bois that I have on the computers around here and some don't have the extended functions, so I don't use them...
Post 31 Mar 2011, 03:31
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BOTOKILLER



Joined: 07 Jan 2011
Posts: 154
Location: Ukraine
BOTOKILLER
roboman wrote:
>AH - 42h
>DL - BIOS device number
>DS:SI - Device address packet

That part agrees with Ralf Brown's Interrupt List. So you are starting at the highest possible device and just working your way down, trying to load the boot sector

mov ds, di ; loading DAP segment
mov di, DAP ; and offset

oopps, the offset should have been put in si. Don't see si in the program, so it's a guess as to what chunk of memory it's reading as a DAP table.

So the software just starts with the last possible device and counts down loading any thing found in the first 4 sectors into the same location it did with the last device, then goes into an endless loop?
Or 400h sectors get copied, depending on whos docs are right.

Hoping to see each drives lights come on as a test? Don't know why the error message, I checked several bois that I have on the computers around here and some don't have the extended functions, so I don't use them...


thanks, the error message is gone, but nothing more, I look into memory through debugger, but nothing on 810h:0000h
VirtualBox wrote:

VBoxDbg> db 8100h:0000h
8100:00000000: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 ................
8100:00000010: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 ................
8100:00000020: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 ................
8100:00000030: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 ................
8100:00000040: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 ................
8100:00000050: 00 00 00 00 00 00 00 00-00 00 00 00 00 00 00 00 ................
VBoxDbg>

about 400h sectors, I think, that I fixed it too
Code:
        USE16
        ORG 07C00h

        START:
        mov ecx, 0FFh

        LOADKERN:
        mov di, DAP_Buff_Addr
        mov dword [cs:di], 8100000h   ; that is where i fixed it
        mov dl, cl
        mov si, cs             ; changed di to si
        mov ds, si
        mov si, DAP
        mov ah, 42h
        pusha
        int 13h
        push ax
        push dx
        mov al, '2'
        jnc FAIL
        pop ax
        pop dx
        AFTERFAIL:
        popa
        loop LOADKERN

;        AMOUNTOFMEMSCAN:
 ;       mov ax, 0E801h
  ;      int 15h
   ;     mov al, '1'
    ;    jc FAIL
     ;   xchg ax, bx
      ;  mov bx, 0FFFFh
       ; mul bx
        ;mov di, MAXMEMADDR
        ;mov [cs:di], eax

        LDSO:
        jmp LDSO

        FAIL:
        mov ah, 0eh
        int 10h
        pop ax
        push ax
        xchg ah, al
        mov ah, 0eh
        int 10h
        pop ax
        pop dx
        jmp LDSO


        DAP:
        DAP_Size            db 10h
        DAP_Res1            db 0
        DAP_Bytes2Transfer  db 4h
        DAP_Res2            db 0
        DAP_Buff_Addr       dd 08100000h
        DAP_LBA             dq 0h
        times 12 db 0

        ;MAXMEMADDR dd 0

        times 1958 db 0
        dw 0AA55h              

i doubt that it reads CD even once, or I just have mor mistakes in my code????
Post 31 Mar 2011, 12:25
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Dex4u



Joined: 08 Feb 2005
Posts: 1601
Location: web
Dex4u
Have you tryed something like this
Code:
        DAP_Size             db 10h
        DAP_Res1             db 0
        DAP_Bytes2Transfer   db 4h
        DAP_Res2             db 0
        DAP_Buff_Addr1       dw 0x0810
        DAP_Buff_Addr2       dw 0
        DAP_LBA              dq 0
    


As if i can remember right some of the info on the net about DAP layout is wrong.
Post 31 Mar 2011, 16:03
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