How is the bit-stream presented ?
If it's a string, you could do something like:
select replace(replace('11010','1','11'),'0','00') from dual;
Regards
Jonathan Lewis
http://www.jlcomp.demon.co.uk
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who can answer the questions, but the
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____UK___November
The Co-operative Oracle Users' FAQ
http://www.jlcomp.demon.co.uk/faq/ind_faq.html
----- Original Message -----
To: "Multiple recipients of list ORACLE-L" <[EMAIL PROTECTED]>
Sent: Tuesday, January 06, 2004 9:39 AM
> Hi,
>
> Well, since I can't sleep, I may as well try solving a problem.
>
> This is a bit odd, and I'm trying to think of the most efficient way to do
> it. I've set up some bitmaps in my app. Consider we have documents that
> we want to sell. In order to be able to sell a given doc, we need to have
it
> stored in the vault and we also need to have negotiated the proper
contract
> w/ the publisher. So, I've got two bitmaps, STORAGE and PERMISSIONS.
>
> But, here's the hook. There are 8 different types of storage, so I have
> an 8 bit mask. However, for every storage type, there are two types of
> permission. So, I have a 16 bit permissions mask.
>
> What I'd like to do is take my 8-bit STORAGE mask, say it's 10110011
> and convert it to 1100111100001111. Note that all I did there was take
> each bit in the input mask, and make the same value repeat. So, 0 would
> become 00, 1 would become 11, 10 would become 1100. Does that make sense?
> Once I've done that, I can take my STORAGE mask that's now stretched to 16
> bits, and directly AND it with my PERMISSIONS mask.
>
> So, my question is: Is there a nice, scalable way to take my 8 bits and
> expand them into 16 bits, in the way that I'm describing? A clever bit
> twiddling expression would be perfect, but anything that's efficient and
> scalable will do. (The end product will be hidden behind a view or stored
> procedure.)
>
> Any thoughts, anyone?
>
> Thanks in advance,
>
> -Mark
> --
> Please see the official ORACLE-L FAQ: http://www.orafaq.net
> --
> Author: Bobak, Mark
> INET: [EMAIL PROTECTED]
>
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--
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--
Author: Jonathan Lewis
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