Converts a byte array to a 32-bits unsigned int array

byte-array-to-fixnum-array.lisp

(defun byte-array-to-ui-32-bit-array (octet-array)
  (declare (optimize (speed 3))
           (type (simple-array (unsigned-byte 8) (*)) octet-array))
  (if (/= (mod (length octet-array) 4) 0)
      (make-array 0 :element-type '(unsigned-byte 32))
      (make-array (/ (length octet-array) 4)
                  :element-type '(unsigned-byte 32)
                  :initial-contents
                  (loop for i from 0 below (length octet-array) by 4
                     for j = 0 then (1+ j)
                     for b0 of-type (unsigned-byte 8) = (aref octet-array i)
                     for b1 of-type (unsigned-byte 8) = (aref octet-array (+ i 1))
                     for b2 of-type (unsigned-byte 8) = (aref octet-array (+ i 2))
                     for b3 of-type (unsigned-byte 8) = (aref octet-array (+ i 3))
                     for element = (logior b0
                                           (ash b1 8)
                                           (ash b2 16)
                                           (ash b3 24))
                     collect element))))