The first question would be:
Is possible to get the position of the first active bit in a string of bits in only one operation ?
An the second of course: How to do it ?
Thanks in advance.
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The first question would be:
Is possible to get the position of the first active bit in a string of bits in only one operation ?
An the second of course: How to do it ?
Thanks in advance.
I have heard there are some processors where getting the highest bit of an integer is a single instruction, but I can not name which ones. Even if there are such processors, you will only be able to get the highest bit of an integer not of an arbitrary binary number, which seems to be the case in your question.
For longer bit sequences I don’t think you have any better option than to check for each bit, while for shorter ones you may precompute the highest bit values(for instance have an array storing the highest bit for all numbers up to 32768) and than simply get a value from that array to have the answer you need for all up to 15 bit sequences.