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

[Paul Nicholls]

I second the motion of using a Dynamic array too instead of the manual 
creation/destruction of a memory block.

I use this for a virtual machine I created a few years back and it works 
under XP/Vista for me :)

cheers,
Paul

----- Original Message ----- 
From: "Jonas Maebe" <jonas.maebe at elis.ugent.be>
To: "FPC-Pascal users discussions" <fpc-pascal at lists.freepascal.org>
Sent: Wednesday, February 23, 2011 7:54 AM
Subject: Re: [fpc-pascal] Re: assign code to a method



On 22 Feb 2011, at 21:24, Angel Montesinos wrote:

> one uncomments the commented line of code, that is  makes
>   codeFunction:= '',
> the program fails.
>
>
> What may be happening here?

This code is wrong:

   functionCode : AnsiString; {the function opCode sequence}
...
   Move(functionCode, PChar(FBlock^.code), len);

An ansistring is a pointer. Move takes formal const/var parameters. So the 
move() moves the pointer along with whatever data comes after it over the 
"FBlock^.code" pointer and whatever data comes after that. What you want, is 
to move the data to which functionCode points into the memory block to which 
FBlock^.code points. 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).


Jonas_______________________________________________
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