number of ``on'' bits in a two's complement number
Major Section:  ACL2-BUILT-INS

(Logcount x) is the number of ``on'' bits in the two's complement representation of x.

(Logcount x) has a guard of (integerp x).

Logcount is a Common Lisp function. See any Common Lisp documentation for more information.

To see the ACL2 definition of this function, see pf.