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 thread  Author  Topic: WM_COPYDATA problem  (Read 295 times)
Nick
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xx Re: WM_COPYDATA problem
« Reply #4 on: Sep 25th, 2013, 1:52pm »
[quote author=Richard Russell
All I can say is that receiving a 'No such variable' message is consistent with heap corruption, so that's something to investigate. [/quote]

OK - I will double check...

[quote author=Richard Russell
Incidentally - although it can't be the source of the problem - your comment 'This has to be fast' seems rather incongruous alongside the actual code, which appears to have been written to be about as slow as possible!

Richard. [/quote]

Thanks for that. Like many experienced programmers with precious little time to go up the learning curve, I usually opt for things that are least likely to be additional reasons for something to break. But I am sure it can be re-written to be faster - your suggestions would be most welcome.

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xx Re: WM_COPYDATA problem
« Reply #5 on: Sep 27th, 2013, 11:23am »
on Sep 25th, 2013, 1:52pm, Nick wrote:
OK - I will double check...

Did you find the fault?

Quote:
But I am sure it can be re-written to be faster - your suggestions would be most welcome.

If the amount of data is substantial (say a kilobyte or more) I would recommend using SYS "RtlMoveMemory" to transfer it:

http://msdn.microsoft.com/en-us/library/windows/hardware/ff562030.aspx

If it's relatively small, a FOR...NEXT loop using static integer variables won't be too bad:

Code:
      S% = source%
      D% = destination%
      FOR I% = 0 TO bytecount%-1 : D%?I%=S%?I% : NEXT

Of course if you know that the byte count is an exact multiple of 4 this will be faster:

Code:
      S% = source%
      D% = destination%
      FOR I% = 0 TO bytecount%-4 STEP 4 : D%!I%=S%!I% : NEXT

Richard.
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