Rotate-left-17
- Signature
(rotate-left-17 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-17$inline
(defun rotate-left-17$inline (x places)
(declare (type (unsigned-byte 17) x)
(type (unsigned-byte 17) places))
(let ((__function__ 'rotate-left-17))
(declare (ignorable __function__))
(mbe
:logic (rotate-left x 17 places)
:exec
(let*
((x (mbe :logic (loghead 17 x) :exec x))
(places (mbe :logic (lnfix places)
:exec places))
(places (mbe :logic (mod places 17)
:exec
(if (< places 17)
(the (integer 0 16) places)
(the (integer 0 16) (rem places 17)))))
(low-num (the (integer 0 17) (- 17 places)))
(mask (the (unsigned-byte 17)
(1- (the (unsigned-byte 18)
(ash 1 low-num)))))
(xl (the (unsigned-byte 17)
(logand x mask)))
(xh (the (unsigned-byte 17)
(logand x
(the (signed-byte 18) (lognot mask)))))
(xh-shift (the (unsigned-byte 17)
(ash xh (the (integer -17 0) (- low-num)))))
(xl-shift (the (unsigned-byte 17)
(ash (the (unsigned-byte 17) xl)
(the (integer 0 17) places))))
(ans (the (unsigned-byte 17)
(logior xl-shift xh-shift))))
ans))))
