[fpc-pascal] Re: assign code to a method

[Angel Montesinos]

> The correct statement is therefore:
>
> Move(functionCode[1], FBlock^.code^, len);
>
> It would also be cleaner to use a dynamic array instead of a string
> to store arbitrary binary data (in that case, you'd have to use
> functionCode[0] above though).

I have tried yours and other combinations. The following one works at 
last in Delphi6 PE. This will keep me occupied some time updating my 
32 bits programs, so that they will be DEP safe. Thanks to you all. 
Note that I have dropped the use of Move. As for fpc-Lazarus 64 bits, 
it does not work yet: more about this in another thread.


{--------------code snippet begins--------------}

   len:= Length(cod);   { cod  is the ansiString containing
                          the opcodes to be executed}
   SetLength(ba, len);   { ba   is an auxiliary array of bytes}
   for i:= 0 to len-1 do
     ba[i]:= ord(cod[i+1]);

   { exeBlock   has been declared as PChar }
   exeBlock:= VirtualAlloc(nil, len + SizeOf(exeBlock), MEM_COMMIT,
           PAGE_EXECUTE_READWRITE);
   for i:= 0 to len-1 do
     exeBlock[i]:= chr(ba[i]);

   @F:= @exeBlock[0];  {  F  is the function whose code is
                        here assigned to  cod}

   ba:= nil;
   cod:= '';

{----------code ended---------------}

For people interested in details: the use of an AnsiString for storing 
the opcodes, that is for building "cod", eases this by the use of the 
special procedures to treat strings (adding them, etc.).
The use of exeBlock as PChar serves to guarantee that a contiguous 
chunk of memory starting in exeBlock[0] becomes reserved for the 
exclusive use of exeBlock and cannot overlap another variable: this is 
my interpretation of the failure that did happen when, after assigning 
the code to F, I did put  cod = ''.


-- 
montesin at uv dot es