+
+(defun 64-bit-logcount (x)
+ (declare (optimize speed) (type (unsigned-byte 54) x))
+ (logcount x))
+(assert (= (64-bit-logcount (1- (ash 1 24))) 24))
+(assert (= (64-bit-logcount (1- (ash 1 32))) 32))
+(assert (= (64-bit-logcount (1- (ash 1 48))) 48))
+(assert (= (64-bit-logcount (1- (ash 1 54))) 54))