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Re: weird behaviour of ishft [message #65681 is a reply to message #65679]

Tue, 17 March 2009 02:46

Foldy Lajos
Messages: 268
Registered: October 2001

Senior Member

On Tue, 17 Mar 2009, BenHur wrote:

> Hi everyone,
>
> Can somebody explain to me, why for certain types ishft shifts only by
> modulo 32 bits?
> Example:
> DISR> print,ishft(1,[31,32])
> 0 1
> DISR> print,!version
> { x86 Win32 Windows Microsoft Windows 6.4 Mar 23 2007 32 64}
>
> I would expect ishft(1,32) = 0. Am I missing something? Is it my
> outdated IDL version or does it happen with newer versions/other
> platforms?
>
> Cheers, Ben
>

It's normal for the right shift (SHR) op on x86 processors. From the Intel
manual: 'The count is masked to 5 bits, which limits the count range to 0
to 31.'

regards,
lajos

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		Re: weird behaviour of ishft By: BenHur on Tue, 17 March 2009 03:37
		Re: weird behaviour of ishft By: Foldy Lajos on Tue, 17 March 2009 02:46

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