data moved with 2 different outputs of .exe

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dosin

Joined: 24 Aug 2007
Posts: 337

dosin 07 May 2009, 16:12

Format MZ
when I move all the data down to the jmp $
it compiles to 10.4 kb .exe in this one
This is the end of the file:

Code:

      mov  esi,endmsg 
      call print_string 

      
      jmp   $ 
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 
;       data       <------------------------here 
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 
include 'errors.inc' 
include 'keymaps.inc' 
include 'Fddinfo.inc' 
include 'msg.inc' 
include 'fat.inc' 

temp_buff:   rb 0x1000 
buffer_area: rb 0x10000 
buffer:      rb 512

and when I put jump over it in the middle of the file:

Code:

jmp inc_over2
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 
;       data  
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;; 
include 'errors.inc' 
include 'keymaps.inc' 
include 'Fddinfo.inc' 
include 'msg.inc' 
include 'fat.inc' 

inc_over2:

it compiles to a 22.9 kb .exe
The data is not change,, just moving the strings and data
around in the .asm file..

can anyone explain why this happening???

07 May 2009, 16:12

r22

Joined: 27 Dec 2004
Posts: 805

r22 07 May 2009, 17:08

Maybe your include(s) contain 12.5KB of "R"eserved data that is forced to be allocated when it's in the middle of the section, but not at the end of the section (where reserved data belongs).

07 May 2009, 17:08

dosin

Joined: 24 Aug 2007
Posts: 337

dosin 07 May 2009, 17:13

Is this a bug?

or is there something I am missing?

07 May 2009, 17:13

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 19869
Location: In your JS exploiting you and your system

revolution 08 May 2009, 01:09

11kB

Code:

jmp There
rb 11 shl 10
There: ret

Code:

ret
rb 11 shl 10

08 May 2009, 01:09

dosin

Joined: 24 Aug 2007
Posts: 337

dosin 08 May 2009, 01:41

Quote:

ret
rb 11 shl 10

shouldn't it be the same?
I have noticed this happening
but I am not sure why?

08 May 2009, 01:41

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 19869
Location: In your JS exploiting you and your system

revolution 08 May 2009, 05:31

rb is uninitialised data. It is not put into the file unless there is some initialised data that follows it. Not a bug, intentional.

08 May 2009, 05:31

dosin

Joined: 24 Aug 2007
Posts: 337

dosin 08 May 2009, 06:38

Code:

;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;  
;       data   
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;  
include 'errors.inc'  
include 'keymaps.inc'  
include 'Fddinfo.inc'  
include 'msg.inc'  
include 'fat.inc'

in these files are data

example: db "Some String",0
number: dd 0
ect....

not rb

and the includes that do not use the rb,, these are the ones being moved..
and the exe is changing size

08 May 2009, 06:38

revolution
When all else fails, read the source

Joined: 24 Aug 2004
Posts: 19869
Location: In your JS exploiting you and your system

revolution 08 May 2009, 08:49

I expect your 'fat.inc' has some uninitialised data at the end.

08 May 2009, 08:49

dosin

Joined: 24 Aug 2007
Posts: 337

dosin 08 May 2009, 15:46

you are right! Thanks revolution...
I was looking at everything but that... Embarassed

08 May 2009, 15:46

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