logand, logandc1, logandc2, logeqv, logior, lognand, lognor, lognot, logorc1, logorc2, logxor Function

Syntax

logand &rest integers result-integer

logandc1 integer-1 integer-2 result-integer

logandc2 integer-1 integer-2 result-integer

logeqv &rest integers result-integer

logior &rest integers result-integer

lognand integer-1 integer-2 result-integer

lognor integer-1 integer-2 result-integer

lognot integer result-integer

logorc1 integer-1 integer-2 result-integer

logorc2 integer-1 integer-2 result-integer

logxor &rest integers result-integer

Arguments and Values

integersintegers.

integer — an integer.

integer-1 — an integer.

integer-2 — an integer.

result-integer — an integer.

Description

The functions logandc1, logandc2, logand, logeqv, logior, lognand, lognor, lognot, logorc1, logorc2, and logxor perform bit-wise logical operations on their arguments, that are treated as if they were binary.

Figure 12–18 lists the meaning of each of the functions. Where an ‘identity’ is shown, it indicates the value yielded by the function when no arguments are supplied.

Negative integers are treated as if they were in two’s-complement notation.

Examples
(logior 1 2 4 8)  15
(logxor 1 3 7 15)  10
(logeqv)  -1
(logand 16 31)  16
(lognot 0)  -1
(lognot 1)  -2
(lognot -1)  0
(lognot (1+ (lognot 1000)))  999

;;; In the following example, m is a mask.  For each bit in
;;; the mask that is a 1, the corresponding bits in x and y are
;;; exchanged.  For each bit in the mask that is a 0, the
;;; corresponding bits of x and y are left unchanged.
(flet ((show (m x y)
(format t "~%m = #o~6,'0O~%x = #o~6,'0O~%y = #o~6,'0O~%"
m x y)))
(let ((m #o007750)
(x #o452576)
(y #o317407))
(show m x y)
(let ((z (logand (logxor x y) m)))
(setq x (logxor z x))
(setq y (logxor z y))
(show m x y))))
m = #o007750
x = #o452576
y = #o317407

m = #o007750
x = #o457426
y = #o312557
NIL
Exceptional Situations

Should signal type-error if any argument is not an integer.

boole

Notes

(logbitp k -1) returns true for all values of k.

Because the following functions are not associative, they take exactly two arguments rather than any number of arguments.

(lognand n1 n2)  (lognot (logand n1 n2))
(lognor n1 n2)  (lognot (logior n1 n2))
(logandc1 n1 n2)  (logand (lognot n1) n2)
(logandc2 n1 n2)  (logand n1 (lognot n2))
(logiorc1 n1 n2)  (logior (lognot n1) n2)
(logiorc2 n1 n2)  (logior n1 (lognot n2))
(logbitp j (lognot x))  (not (logbitp j x))