made my first Code [resolved]

Index > DOS > made my first Code [resolved]

Author

Thread

packet_50071

Joined: 31 Oct 2007
Posts: 15

packet_50071 02 Nov 2007, 23:24

this is my code

Code:

Ary db 123,145,143,146,0

lea ecx,[Ary]

startl:
mov eax,[ecx]
cmp eax,0
je quit
cmp ebx,eax
jle startl
mov ebx,eax
inc ecx
jmp startl

quit:
mov ax,4C00h
int 21h

I want to check if it works - i want it to show the highest value [which is in the ebx --- I hope]

Any help would be great Smile

Last edited by packet_50071 on 03 Nov 2007, 18:59; edited 1 time in total

02 Nov 2007, 23:24

bitRAKE

Joined: 21 Jul 2003
Posts: 4043
Location: vpcmpistri

bitRAKE 03 Nov 2007, 01:55

Some brief comments:

Code:

startl:
mov eax,[ecx]  ; Ary is bytes, but you load DWORD!
cmp eax,0
je quit
cmp ebx,eax      ; what is in EBX the first time?!
jle startl ; this will loop, but ECX hasn't been changed
mov ebx,eax
inc ecx                ; this should be in innerloop
jmp startl

quit:
mov ax,4C00h
int 21h

This looks like DOS code - should be posted in the DOS section, imho.

03 Nov 2007, 01:55

packet_50071

Joined: 31 Oct 2007
Posts: 15

packet_50071 03 Nov 2007, 16:06

Code:

mov eax,[ecx]   ; Ary is bytes, but you load DWORD!

How do I load the byte !

Should I repost this in DOS !

03 Nov 2007, 16:06

vid
Verbosity in development

Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia

vid 03 Nov 2007, 16:30

use byte-sized register:

Code:

mov al, [ecx]
mov bh, [ecx]

03 Nov 2007, 16:30

bitRAKE

Joined: 21 Jul 2003
Posts: 4043
Location: vpcmpistri

bitRAKE 03 Nov 2007, 17:40

I used DEBUG from DOS when I first moved to Intel land. Hopefully, there are better debuggers in DOS, but I don't know what is availible in that regard. A good debugger will allow you to program in memory and test as you go - interactively. I piped instruction from a batch file to 'compile' my programs. Smile

Ollydbg works well for this in Windows.

In a debugger you will see a representation of internal machine state to better understand what is happening with each instruction. This is a good start.

03 Nov 2007, 17:40

packet_50071

Joined: 31 Oct 2007
Posts: 15

packet_50071 03 Nov 2007, 18:50

Thx for the help Smile

I will stick with fasm for now - when I move to Windows I will use Visual studio
its a good debugger for Windows Wink

My working code Smile

Code:

org 100h

mov ah,2
lea ecx,[Ary]
mov dl,0

startl:
mov al,[ecx]

cmp al,0
je quit

inc ecx

cmp al,dl
jle startl

mov dl,al
jmp startl

quit:
int 21h
mov ax,4C00h
int 21h

Ary db 109,108,102,0

03 Nov 2007, 18:50

bitRAKE

Joined: 21 Jul 2003
Posts: 4043
Location: vpcmpistri

bitRAKE 03 Nov 2007, 19:47

Here are some DOS tools:
http://www.japheth.de/

03 Nov 2007, 19:47

Japheth

Joined: 26 Oct 2004
Posts: 151

Japheth 04 Nov 2007, 08:36

For such a simple program DEBUG is good enough:

http://www.japheth.de/Download/debug107.zip

David Lindauer has coded GRDB, which also has the nice and superior DEBUG interface + some goodies:

http://members.tripod.com/~ladsoft/grdb.htm

For those loving warm showers, there are fullscreen debuggers available as well:

http://www.bttr-software.de/products/insight/
http://www.programmersheaven.com/download/21643/download.aspx

04 Nov 2007, 08:36

< Last Thread | Next Thread >

Forum Rules:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum