8-bit pattern search in c#`

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I need a code in c#, for searching a specific pattern, say 01111110, from the data.
Any help will be appreciated.

Regards

Posted 6-Jul-11 20:18pm

nailaS

Updated 6-Jul-11 21:17pm

Dalek Dave

v2

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Dalek Dave 7-Jul-11 3:17am

Edited for Grammar and Readability.

BobJanova 7-Jul-11 6:07am

Please be more clear about what you are actually wanting to do, in particular whether the patterns may cross byte boundaries. For example, should the byte sequence [07, E2] – 0000 0111 1110 0010 – match?

3 solutions

Solution 2

Check the following articles they might help you:

http://stackoverflow.com/questions/283456/byte-array-pattern-search[^]

http://www.lulu.com/items/volume_63/1995000/1995848/9/print/all.pdf[^]

Posted 6-Jul-11 20:34pm

Jamil Hallal

Solution 1

you can convert the 8-bit pattern into a byte, then you can transform the next
8-bits into a byte and compare it...

Posted 6-Jul-11 20:32pm

Denis9999

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Dalek Dave 7-Jul-11 3:18am

Nice idea, but a little ungainly.

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Timberbird · Accepted Answer · 2011-07-06T20:49:00

Solution 3

As far as I understand, you are not looking for a specific byte matching your pattern (that would be trivial, searching byte[] array), but your need to match pattern anywhere in the data, maybe crossing byte boundaries? If so, I can only offer you to scan each byte of data for the bit your pattern starts with, then compare next bit (maybe taken from the next byte, if you must cross byte boundaries) with the second bit of a pattern and so on. Definitely this - very straightforward - algorithm may be improved. Check algorithms for substring search, they may be applied here

Posted 6-Jul-11 20:49pm

Timberbird

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Sergey Alexandrovich Kryukov 7-Jul-11 3:20am

Agree, my 5 (I'm not sure OP formulated the problem correctly though). I would note: algorithms for substring search should be applied (most certainly) but never the implementations as they are only applied to characters, not bits. However, relatively simple modification of such algorithms to bit patterns can be quite feasible.
--SA

Timberbird 7-Jul-11 3:49am

Thank you. Well, I thought noone would care to post a question regarding simple byte search :). On the other hand, there may be ready-to-use tools for pattern search - for example, in streams; unfortunately, I don't know of any

Sergey Alexandrovich Kryukov 8-Jul-11 1:59am

I'm not sure there are tools searching a bit pattern across byte boundaries as you suggested. They can be obtained via modification of existing pattern search algorithms. The fact that they are readily available and we all use them does not make them trivial -- I recently saw descriptions of some -- quite brain-bending :-)
--SA