Previous power of 2

Question

There is a lot of information on how to find the next power of 2 of a given value (see refs) but I cannot find any to get the previous power of two.

The only way I f

Answer 1

When you work in base 2, you can jump from a power of two to the next one by just adding or removing a digit from the right.

For instance, the previous power of two of the number 8 is the number 4. In binary:

01000 -> 0100 (we remove the trailing zero to get number 4)

So the algorithm to solve the calculus of the previous power of two is:

previousPower := number shr 1

previousPower = number >> 1

(or any other syntax)