logand, logandc1, logandc2, logeqv, logior,

lognand, lognor, lognot, logorc1, logorc2,

logxor

[Function]

logand {&rest integers} => result-integer

logandc 1 => integer-1 integer-2 {result-integer} logandc 2 => 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

logorc 1 => integer-1 integer-2 {result-integer} logorc 2 => 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.

Figure 12--17 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--17: 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 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.

See Also::

section boole [Function]

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))

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