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Altering functions(class methods), procedures inside CE.

 
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mgr.inz.Player
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PostPosted: Fri Dec 02, 2011 8:52 pm    Post subject: Altering functions(class methods), procedures inside CE. Reply with quote

Hi Dark Byte.

I'm interested in making small plugin. But I better learn on examples. Lets say I want to alter this function: (btw. look at this):

TScanner.CustomIncreasedValueByPercentage

like this:
Quote:
function TScanner.CustomIncreasedValueByPercentage(newvalue,oldvalue: pointer): boolean;
begin
result:=(customType.ConvertDataToInteger(newvalue)>trunc(customType.ConvertDataToInteger(oldvalue)+
customType.ConvertDataToInteger(oldvalue)^*svalue)) and (customType.ConvertDataToInteger(newvalue)<trunc(customType.ConvertDataToInteger(oldvalue)+customType.ConvertDataToInteger(oldvalue)*svalue2));
end;



So, I ask you to do minimum version of the Unit1.pas file (inside example-lazarus folder) and Lazarus Project.
(pretty please? Laughing)



I know there should be this
Code:
uses windows, LCLIntf,sysutils, classes,ComCtrls,dialogs,
     NewKernelHandler, math, SyncObjs
     , windows7taskbar,SaveFirstScan, savedscanhandler, autoassembler, symbolhandler,
     CEFuncProc,shellapi, customtypehandler,lua,lualib,lauxlib, LuaHandler, fileaccess,
     forms,StdCtrls,ExtCtrls;
(more or less)

And I must import many files from Cheat Engine project.



Is it possible to alter TMainForm.UpdateScanType procedure with plugin?

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Dark Byte
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PostPosted: Sat Dec 03, 2011 2:40 am    Post subject: Reply with quote

Not with the plugin. But you can use lua to hide the old vartype , scantype, firstscan/nextscan components on mainform and replace them with your own

Well, you could of course do an aobscan for that function and hook it to a function in your own dll, but the chance that that just fails when I make a change (like just recompiling) is quite big

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mgr.inz.Player
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PostPosted: Sat Dec 03, 2011 9:19 am    Post subject: Reply with quote

Dark Byte wrote:
Not with the plugin(....)
(...)you could of course do an aobscan for that function and hook it to a function in your own dll, but the chance that that just fails when I make a change (like just recompiling) is quite big

OK. But if my plugin will be only for particular CE version; should work. So I will distribute DLL with EXE (cheatengine-i386_for_plugin.exe)


For now, I only changed CE source. (this is why I wanted to try make a plugin)

Diff file for CE source (diff , diff mirror)

I added this:
alloc(treatAsFloat,1) - Custom type is treated as float type (pnlfloat is visible, rounding enabled, search result aren't saved when NaN or Infinite)

alloc(fastScanAlignSize,4) - Now alignsize do not depend on bytesize


Tested above modifications. Assassin's Creed Brotherhood hero position structure:

float placeholder0 // Always 1.0 (0x3f800000) (not hanging)
float placeholder1 // Always 0.0 (0x00000000)
float X // player X pos
float Y // player Y pos
float Z // player Z pos, always bigger than (-1000); probably always bigger than (-50)
float placeholder2 // Always 1.0 (0x3f800000)

placeholder0 offset 0x00
placeholder1 offset 0x04
placeholder2 offset 0x14
Z offset 0x10

Bytesize is 24. Alignsize is 4 (this is why I made fastscanalignsize)



So, if eax is an address that contains the bytes, then:

cmp dword ptr [eax+00],(float)1
jne SKIP

cmp dword ptr [eax+04],0
jne SKIP

cmp dword ptr [eax+14],(float)1
jne SKIP

and [eax+10] is smaller than -1000 or NaN, then SKIP

SKIP returns this: EAX=0xFFFFFFFF (NaN)


Whole AA custom type script I use:
Code:
alloc(TypeName,256)
alloc(ByteSize,4)
alloc(treatAsFloat,1)
alloc(fastScanAlignSize,4)

alloc(ConvertRoutine,1024)
alloc(ConvertBackRoutine,1024)

label(TEMPVAL)
label(SKIP)

TypeName:
db 'AC:B Z coordinate',0

ByteSize:
dd (int)24 // struct has 20 bytes

fastScanAlignSize:
dd 4

ConvertRoutine:
push ebp
mov ebp,esp
mov eax,[ebp+8] //place the address that contains the bytes into eax

cmp dword ptr [eax],(float)1
jne SKIP

cmp dword ptr [eax+04],0
jne SKIP

cmp dword ptr [eax+14],(float)1
jne SKIP

finit

push eax        // save EAX
push (int)-1000 // Z coordinate is always bigger than -1000


fld [eax+10]
ficomp dword ptr [esp]
fstsw word ptr [esp]
fwait
pop eax   // get status word
sahf      // transfer status word to CPU's flag register
pop eax   // restore original EAX
jpe SKIP  // NaN, skip
jb SKIP   // less than -1000, SKIP


mov eax,dword ptr [eax+10] //get value

pop ebp
ret 4

SKIP:
mov eax,7fffffff   // set NaN, easy to filter out
pop ebp
ret 4

TEMPVAL:
dd 0

ConvertBackRoutine:
push ebp
mov ebp,esp
push eax
push ebx

mov eax,[ebp+8] //load the value into eax
mov ebx,[ebp+c] //load the address into ebx

mov [ebx+10],eax //write the value into the address

pop ebx
pop eax
pop ebp
ret 8





Then I searched custom type float(AC:B Z coordinate) increased, decreased. (I got ~40 results after third scan, instead >1000 after 11th scan when only float)



Modifications aren't finished, functions CreateTypeFromLuaScript, registerCustomTypeLua, registerCustomTypeAutoAssembler.



EDIT:
updated diff files. I forgot to use customType.ConvertDataToInteger inside TScanner.GenericSaveResult function.

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