Question

For bit-wise shift (or rotation, circulation) operations, we usually have an operator, i mean two of them, for instance

x << n
x >> n

for left or right shift of x by n bits.

We want to define a single function

bitshift(x, n)

Before that, we have to determine, which shift is to be used for positive and negative n – what is the "sign" of each shift (or rotation) direction.

Is there a definition or convention for that?

(Please note that this question has nothing to do with signed/unsigned types)

UPDATES

Please also note that i am not asking for implementation details of this function, even it might be somewhat related..

There are similar functions in scheme/lisp-like languages, like ash, which do left shift for positive n

Answer 1

Since shifting right by k places is equal to multiplying by 2^-k, and shifting left is equal to multiplying by 2^k, I think that should give you a hint.

Note: Reason I would argue for this way of looking at it is that it is common to consider multiplication as more fundamental operation in some sense than division is, although you could certainly argue the other way around.