Function: lsh

lsh is a byte-compiled function defined in subr.el.gz.

Signature

(lsh VALUE COUNT)

Documentation

Return VALUE with its bits shifted left by COUNT.

If COUNT is negative, shifting is actually to the right. In this case, if VALUE is a negative fixnum treat it as unsigned, i.e., subtract 2 * most-negative-fixnum from VALUE before shifting it.

Other relevant functions are documented in the number group.

Shortdoc

;; number
(lsh 1 4)
    => 16
  (lsh 16 -1)
    => 8

Source Code

;; Defined in /usr/src/emacs/lisp/subr.el.gz
(defun lsh (value count)
  "Return VALUE with its bits shifted left by COUNT.
If COUNT is negative, shifting is actually to the right.
In this case, if VALUE is a negative fixnum treat it as unsigned,
i.e., subtract 2 * `most-negative-fixnum' from VALUE before shifting it."
  (when (and (< value 0) (< count 0))
    (when (< value most-negative-fixnum)
      (signal 'args-out-of-range (list value count)))
    (setq value (logand (ash value -1) most-positive-fixnum))
    (setq count (1+ count)))
  (ash value count))