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Subject: Re: EPICS base V4: iocCore database
From: Benjamin Franksen <benjamin.franksen@bessy.de>
To: Jeff Hill <johill@lanl.gov>
Cc: 'Marty Kraimer' <mrk@aps.anl.gov>, 'Andrew Johnson' <anj@aps.anl.gov>, 'Bob Dalesio' <ldalesio@lanl.gov>, 'Ralph Lange' <Ralph.Lange@mail.bessy.de>, 'Eric Norum' <norume@aps.anl.gov>, 'Ken Evans' <evans@aps.anl.gov>, 'Ned Arnold' <nda@aps.anl.gov>, 'Matej Sekoranja' <matej.sekoranja@ijs.si>
Date: Wed, 23 Feb 2005 17:10:02 +0100
On Wednesday 23 February 2005 16:48, Jeff Hill wrote:
> > The bottom line is that unsigned types should be used only in
> > the very few cases where they are essential to
> > faithfully represent raw hardware values.
>
> I find that unsigned types are quite useful for situations where
> the operand must never be negative. For example, with array
> indexes this improves performance and simplifies the code when
> range checking because only one side of the range check need be
> done. Of course, I can't expect that everyone will agree :-)

I thought it was obvious from the context (but maybe I should have stated it 
explicitly) that I was only talking about record field and corresponding CA 
data types, not programming in general. Record field values are rarely used 
directly as indices into arrays and even if they would be, the overhead 
involved in using them would be orders of magnitude larger than any overhead 
due to additional range checks.

Ben


Replies:
RE: EPICS base V4: iocCore database Jeff Hill
References:
RE: EPICS base V4: iocCore database Jeff Hill

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