On 22/12/20 19:31, David Laight wrote:
/*
* Use 2ULL to incorporate the necessary +1 in the shift; adding +1 in
* the shift count will overflow SHL's max shift of 63 if s=0 and e=63.
*/
A comment of the desired output value would be more use.
I think it is:
return 'e-s' ones followed by 's' zeros without shifting by 64.
What about a mix of the two:
/*
* Return 'e-s' ones followed by 's' zeros. Note that the
* apparently obvious 1ULL << (e - s + 1) can shift by 64 if
* s=0 and e=63, which is undefined behavior.
*/
Paolo
