![[XANALYS]](../Graphics/XanSmall.gif)
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:
integers---integers.
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.
The next figure 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.
Function Identity Operation performed logandc1 --- and complement of integer-1 with integer-2 logandc2 --- and integer-1 with complement of integer-2 logand -1 and logeqv -1 equivalence (exclusive nor) logior 0 inclusive or lognand --- complement of integer-1 and integer-2 lognor --- complement of integer-1 or integer-2 lognot --- complement logorc1 --- or complement of integer-1 with integer-2 logorc2 --- or integer-1 with complement of integer-2 logxor 0 exclusive or
Figure 12-18. Bit-wise Logical Operations on Integers
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
Side Effects: None.
Affected By: None.
Exceptional Situations:
Should signal type-error if any argument is not an integer.
See Also:
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))