Bitwise Operators in LISP

In this article, we will discuss the Bitwise operators in LISP. These operators are used to perform the manipulation of individual bits of a number. The truth table for bitwise AND, NAND, OR, XOR, NOR, & XNOR: 

Different bitwise operators in LISP are listed below in the tabular form

 Let’s understand each operator one by one.

• logand: It takes two numbers as operands and does logical AND on every bit of two numbers and returns it, If no operands are given then the result is -1

a = 5 = 0101 (In Binary)
b = 7 = 0111 (In Binary)

logand Operation of 5 and 7
    0101
    0111
 ________
=    0101  = 5 (In decimal) 

• logior: The operator returns bitwise Inclusive OR of the arguments that are passed, If only a single argument is passed it will return the argument itself

a = 5 = 0101 (In Binary)
b = 7 = 0111 (In Binary)

logior Operation of 5 and 7
  0101
  0111
 ________
= 0111  = 7 (In decimal) 

• logxor: It returns the bitwise Exclusive OR of its arguments, if no arguments are passed it returns 0

a = 5 = 0101 (In Binary)
b = 7 = 0111 (In Binary)

logxor Operation of 5 and 7
  0101
^ 0111
 ________
= 0010  = 2 (In decimal) 

• lognor: The operator returns bitwise NOT of its arguments, if no arguments are passed it returns -1

a = 5 = 0101 (In Binary)
b = 7 = 0111 (In Binary)

lognor Operation of 5 and 7

    0101
    0111
_________    
= -(1000) = -8 in decimal    

• logeqv: The operator takes two arguments and does Exclusive Nor(i.e. Logical Equivalence) of those arguments, if no arguments are given then it returns -1

a = 5 = 0101 (In Binary)
b = 7 = 0111 (In Binary)

logeqv Operation of 5 and 7
  0101
  0111
 ________
= 1101         XNOR is just inversion of XOR

• logcount: The operator counts the number of bits in an integer, If the number is positive then 1-bits are counted, if it’s negative then 0-bits in two’s complement are counted.

a = 7 = 0111 (in Binary)

logcount Operation of 5

= 0111
   ^^^    there are three 1-bits
   
 Hence the logcount of 7 will return 3

Example:

Shift Operators in LISP

In LISP, for an arithmetic shift, the ash function is used. If the count is positive it shifts the bits to left, else if the count is negative it does the right shift.

Syntax :    ash number count

Example:

sh 10 5;     arithmetic left shift
ash 10 -5;  arithmetic right shift

Output : 

320
0