Rotate-left-8
- Signature
(rotate-left-8 x places) → *
- Arguments
- x — The bit vector to be rotated left.
- places — The number of places to rotate left.
Definitions and Theorems
Function: rotate-left-8$inline
(defun rotate-left-8$inline (x places)
(declare (type (unsigned-byte 8) x)
(type (unsigned-byte 8) places))
(let ((__function__ 'rotate-left-8))
(declare (ignorable __function__))
(mbe
:logic (rotate-left x 8 places)
:exec
(let* ((x (mbe :logic (loghead 8 x) :exec x))
(places (mbe :logic (lnfix places)
:exec places))
(places (mbe :logic (mod places 8)
:exec
(if (< places 8)
(the (integer 0 7) places)
(the (integer 0 7) (rem places 8)))))
(low-num (the (integer 0 8) (- 8 places)))
(mask (the (unsigned-byte 8)
(1- (the (unsigned-byte 9)
(ash 1 low-num)))))
(xl (the (unsigned-byte 8) (logand x mask)))
(xh (the (unsigned-byte 8)
(logand x (the (signed-byte 9) (lognot mask)))))
(xh-shift (the (unsigned-byte 8)
(ash xh (the (integer -8 0) (- low-num)))))
(xl-shift (the (unsigned-byte 8)
(ash (the (unsigned-byte 8) xl)
(the (integer 0 8) places))))
(ans (the (unsigned-byte 8)
(logior xl-shift xh-shift))))
ans))))
