clojure.core/bit-shift-right

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Type: function Added: Clojure 1.0 Examples: 4 Runnable: 4

([x n])

Bitwise shift right

Examples

by devijvers on 2010-07-25 ▶

;; Convert number into list of bits: (defn bits [n s] (take s (map (fn [i] (bit-and 0x01 i)) (iterate (fn [i] (bit-shift-right i 1)) n)))) ;; #'user/bits (map (fn [n] (bits n 3)) (range 8)) ;;=> ((0 0 0) (1 0 0) (0 1 0) (1 1 0) (0 0 1) (1 0 1) (0 1 1) (1 1 1))

by zmila on 2010-07-28 ▶

(bit-shift-right 2r1101 0) ;;=> 13 (bit-shift-right 2r1101 1) ;;=> 6 (bit-shift-right 2r1101 2) ;;=> 3 (bit-shift-right 2r1101 3) ;;=> 1 (bit-shift-right 2r1101 4) ;;=> 0

by fasiha on 2016-04-07 ▶

;; Warning: bit-shift-right upcasts arguments to Long and returns Long (format "0x%x" (byte -128)) ; => "0x80" (format "0x%x" (bit-shift-right (byte -128) 1)) ; You'd expect 0x40? ; => "0xffffffffffffffc0" ; You'd expect 0x40, but (byte -128) was converted to (long -128) and then ; right-shifted, with the negative sign bit of 1 propagated. ; This can't be avoided by using unsigned-bit-shift-right: (format "0x%x" (unsigned-bit-shift-right (byte -128) 1)) ; => "0x7fffffffffffffc0" ; If you want unsigned "byte" operations, upcast the byte yourself via bit-and: (format "0x%x" (bit-shift-right (bit-and 0xff (byte -128)) 1)) ; => "0x40" ; This works because the output of bit-and is always Long: (type (bit-and 0xff (byte -128))) ; => java.lang.Long ; Note that bit-and returns Long even if both arguments are smaller: (type (bit-and (short 0xff) (byte -128))) ; => java.lang.Long

by Sophia-Gold on 2017-01-09 ▶

;; floating point bit-shifting ;; thanks to Gary Fredericks: https://github.com/gfredericks/doubles (defn bit-shift-double [x shifts] (let [x-long (Double/doubleToRawLongBits x)] (Double/longBitsToDouble (bit-or (bit-and 1 x-long) (bit-shift-left (- (bit-shift-right x-long 52) shifts) 52) (bit-and 0xfffffffffffff x-long)))))

Note by TimMc

From the IRC channel, a way to get zero-fill bit-shift-right:

06:08 < mikera> (defn >>> [v bits] (bit-shift-right (bit-and 0xFFFFFFFF v) bits))

There's also an open ticket for a built-in version.

Note by jafingerhut

unsigned-bit-shift-right was added in Clojure 1.6.0. Click the link in the See Also section above.

See also

• clojure.core/bit-shift-left (2)
• clojure.core/bit-xor (2)
• clojure.core/bit-or (2)
• clojure.core/bit-and (4)
• clojure.core/bit-set (2)
• clojure.core/bit-test (3)
• clojure.core/bit-flip
• clojure.core/bit-and-not (3)
• clojure.core/bit-clear
• clojure.core/unsigned-bit-shift-right (3)

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