Re: memcpy

["Bill Meecham" <bmeecham@xxxxxxxxxxxxxxxxxxxx>]

Barbara - That  would be me.  Thank you for the heads-up.  I'll convert the
screen capture code to use memmove instead of memcpy and see how it goes.
BTW, the 'not that I have a use for it' part of what I typed referred to the
screen capture utility that this thread originated from.  Not much use for
that but I definitely have use for procedures!  Thanks again!
Bill

----- Original Message -----
From: <bmorris@ca.ibm.com>
To: <RPG400-L@midrange.com>
Sent: Wednesday, January 03, 2001 6:23 PM
Subject: memcpy


>
> (Sorry, I'm not sure who wrote the quoted sentence ...)
>
>  >> Not that I have a use for it but the way you used the QC2LE binding
>   directory and memcpy are well worth the educational effort.
>
> While memcpy is the most common way to move data, it has a somewhat
> surprising quirk: the result is undefined if the operands overlap.
>
> memmove (builtin function _MEMMOVE) handles overlapping data correctly.
>
> RPG had to change from using MEMCPY to MEMMOVE in generated code; at
> the time I did some performance tests, and the performance was only very
> very slightly worse for MEMMOVE, undetectable except for very long
> lengths.
>
> If you have memcpy prototypes, you can easily switch to memmove by
> changing the EXTPROC to EXTPROC('_MEMMOVE').
>
> Barbara Morris


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