[ros-dev] About GDIOBJHDR header changes

[Magnus Olsen]

Hi Jim and Timo
I base it on how dxg.sys acts when it lock a 
dx object. 
rember that DWORD store data diffent 
the 2 we see it should be the type
rember that the byte order for DWORD is 
casted it mean if it got 2 it is store in the higher part
see memory layout

memory layout 
 ---------------------------------
| WORD 00  | bit 0-15   |
 ---------------------------------
| WORD 01  | bit 16-31 |
 ---------------------------------

word 01 and word 00 are swaped when it display as DWORD, in DWORD the word 01 will become bit 0-15, word 00 will become bit 16-31
that expain the value 0,1,2,3 we see in PVOID Entry. if we split it. we will see value 0,1,2,3,4 in Type amd count is often 0.
I have no clude yet what diffent type it exists. 

the count is often set to 0
and the type is set to 0, 1, 2, 3 and so on. 

Still any unclear why I think it we should Split PVOID into two diffent members ?




----- Original Message ----- 
  From: Timo Kreuzer 
  To: ReactOS Development List 
  Sent: Sunday, December 30, 2007 4:24 AM
  Subject: Re: [ros-dev] About GDIOBJHDR header changes


  James Tabor schrieb: 
Hi!

  typedef struct _GDIOBJHDR
{
    HGDIOBJ     hHmgr;
    PVOID       unknownCount;
    ULONG       cExcLock;
    ULONG       Tid;
}GDIOBJHDR, PGDIOBJHDR;

    I thought PVOID unknownCount was PVOID pEntry which is the pointer
back to the handle table entry. That could have changed since this is
based on Yuan book and w2k. Remember too, that DxDD handles are
different and handled outside normal DC's.
  Yuan says it's pEntry, I came to the conclusion it's probably a counter, because it's values are small like 1,2,3..0x200
  see http://www.reactos.org/wiki/index.php/Techwiki/win32k/GDIOBJHDR
  Has probably changed from 2k to xp.
  I agree, DX objects might be different, maybe they have a different header structure, I have never looked at DX object memory, so I don't know how they look...
  I just can say that all GDI objects I have dumped the memory of, don't have a type field there, it's always been 0.

  Timo




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