Operators in Verilog

Operators in Verilog form the backbone of computational and logical functions within digital designs. They enable the manipulation, computation, and logical assessment of signals and variables, shaping the behavior and functionality of hardware models.

This section delves into the diverse spectrum of operators, their functionalities, and best practices for their effective application within Verilog designs.

Operators in Verilog

Operators in Verilog are fundamental symbols that facilitate mathematical computations, logical evaluations, and bit-level manipulations within digital designs. Categorized into different types, these operators play a pivotal role in defining the behavior and functionality of hardware models.

There are six types of operators in Verilog. These are:

  1. Arithmetic Operators: Used for mathematical computations such as addition, subtraction, multiplication, division, and modulus.
  2. Relational Operators: Facilitate comparisons between values, including equality, inequality, greater than, less than, and their respective combinations.
  3. Equality Operators :
  4. Logical Operators: Manage logical operations like AND, OR, and NOT, aiding in conditional evaluations.
  5. Bitwise Operators: Handle bit-level operations such as AND, OR, XOR, and bit shifting.
  6. Conditional Operator: Allows for conditional assignment based on a condition.
  7. Concatenation Operator: Combines multiple values or signals into a single value or signal.

Arithmetic Operators

Arithmetic operators in Verilog facilitate mathematical computations within digital designs. These operators enable the manipulation of numerical values, allowing for addition, subtraction, multiplication, division, and modulus operations.

%Modulus (Remainder)
Arithmetic Operators in Verilog
Operand AOperand BOperatorResult
001 (1)010 (2)+011 (3)
101 (5)011 (3)-010 (2)
010 (2)110 (6)*100 (4)
111 (7)010 (2)/011 (3)
110 (6)011 (3)%000 (0)
Arithmetic Operations on 3-Bit Binary Numbers in Verilog
module MultiBitArithmetic(
    input [3:0] operand_A, // 4-bit input operand A
    input [3:0] operand_B, // 4-bit input operand B
    output reg [6:0] sum, // 7-bit output for sum
    output reg [6:0] difference, // 7-bit output for difference
    output reg [7:0] product, // 8-bit output for product
    output reg [6:0] quotient, // 7-bit output for quotient
    output reg [3:0] remainder // 4-bit output for remainder

    // Arithmetic operations
    always @( * ) begin
        sum = operand_A + operand_B; // Addition
        difference = operand_A - operand_B; // Subtraction
        product = operand_A * operand_B; // Multiplication
        quotient = operand_A / operand_B; // Division
        remainder = operand_A % operand_B; // Modulus (Remainder)

    // Displaying results
    initial begin
        $display("Operand A: %b", operand_A);
        $display("Operand B: %b", operand_B);
        $display("Sum: %b", sum);
        $display("Difference: %b", difference);
        $display("Product: %b", product);
        $display("Quotient: %b", quotient);
        $display("Remainder: %b", remainder);


In this Verilog module:

  • Arithmetic operators (+, -, *, /, %) are used to perform computations on input variables operand_A and operand_B.
  • sum, difference, product, quotient, and remainder represent the results of corresponding arithmetic operations.

Arithmetic operators are essential for performing mathematical calculations within Verilog designs, enabling designers to model complex numerical computations required in digital systems.

Relational operators

Relational operators in Verilog are used for comparing values and producing Boolean results based on the comparison. Relational operators in Verilog compare operands and return a Boolean value (1 for true, 0 for false) based on the comparison.

List of Relational Operators

a < b‘a’ less than ‘b’
a > b‘a’ greater than ‘b’
a <= b‘a’ less than or equal to ‘b’
a >= b‘a’ greater than or equal to ‘b’

Equality Operator

Equality operators in Verilog are used to compare values and determine equality between operands. Verilog provides four equality operators, including strict equality and non-strict equality, considering various states such as x (unknown) and z (high-impedance).

List of Equality Operators

a === ba equal to b, including x and z
a!== ba not equal to b, including x and z
a == ba equal to b, result can be unknown
a != ba not equal to b, result can be unknown