;;; lib/obj/hash/hasher.lisp --- Hash Functions

 ;;

 ;;; Code:

 (in-package :obj/hash)

 (macrolet ((specialize (str body)       ; TODO 2023-12-21: test if this actually compiles to fastpath

              `(if (typep ,str '(simple-array character 1))

                   ,body

                   ,body)))

   (defun djb (string)

     (declare (string string)

              (optimize speed))

     (let ((hash 5381))

       (declare ((and unsigned-byte fixnum) hash))

       (specialize

        string

        (dotimes (n (min 6 (length string)))

          (setf hash

                (logand most-positive-fixnum

                        (logxor (* hash 33)

                                (char-code (schar string n)))))))

       hash)))