Unlocking the Power of Verilog Operators - Part 10 of our Verilog Series

2024-03-08 | By DWARAKAN RAMANATHAN

What are Verilog Operators and its types:

In Verilog, operators are symbols or special characters used to perform various operations on data, such as arithmetic calculations, logical comparisons, and bit manipulation. Verilog operators allow you to manipulate and process signals and data within your hardware description, making them a fundamental part of the language. Verilog operators can be categorized into several types, each serving a specific purpose:

1. Arithmetic Operators:

+ (Addition): Adds two values together.

result = a + b; // Add 'a' and 'b' and store the result in 'result'.

- (Subtraction): Subtracts the second value from the first.

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result = a - b; // Subtract 'b' from 'a' and store the result in 'result'.‎

* (Multiplication): Multiplies two values.

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result = a * b; // Multiply 'a' by 'b' and store the result in 'result'.‎

/ (Division): Divides the first value by the second.

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result = a / b; // Divide 'a' by 'b' and store the result in 'result'.‎

% (Modulus): Computes the remainder of the division.

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result = a % b; // Calculate the remainder when 'a' is divided by 'b' and ‎store it in 'result'.‎

2. Relational Operators:

== (Equal to): Checks if two values are equal.

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equal = (a == b); // Set 'equal' to 1 if 'a' is equal to 'b', 0 otherwise.‎

!= (Not equal to): Checks if two values are not equal.

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not_equal = (a != b); // Set 'not_equal' to 1 if 'a' is not equal to 'b', 0 ‎otherwise.‎

< (Less than): Checks if the first value is less than the second.

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less_than = (a < b); // Set 'less_than' to 1 if 'a' is less than 'b', 0 ‎otherwise.‎

> (Greater than): Checks if the first value is greater than the second.

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greater_than = (a > b); // Set 'greater_than' to 1 if 'a' is greater than 'b', ‎‎0 otherwise.‎

<= (Less than or equal to): Checks if the first value is less than or equal to the second.

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less_than_or_equal = (a <= b); // Set 'less_than_or_equal' to 1 if 'a' is less ‎than or equal to 'b', 0 otherwise.‎

>= (Greater than or equal to): Checks if the first value is greater than or equal to the second.

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greater_than_or_equal = (a >= b); // Set 'greater_than_or_equal' to 1 if 'a' ‎is greater than or equal to 'b', 0 otherwise.‎

3. Logical Operators:

&& (Logical AND): Performs a logical AND operation on two conditions.

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result = (condition1 && condition2); // Set 'result' to 1 if both 'condition1' ‎and 'condition2' are true, 0 otherwise.‎

|| (Logical OR): Performs a logical OR operation on two conditions.

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result = (condition1 || condition2); // Set 'result' to 1 if either ‎‎'condition1' or 'condition2' is true, 0 otherwise.‎

! (Logical NOT): Negates a logical condition.

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result = !condition; // Set 'result' to the opposite of 'condition' (1 if ‎‎'condition' is false, 0 if 'condition' is true).‎

4. Bitwise Operators:

& (Bitwise AND): Performs a bitwise AND operation on two values.

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result = a & b; // Perform a bitwise AND between 'a' and 'b' and store the ‎result in 'result'.‎

| (Bitwise OR): Performs a bitwise OR operation on two values.

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result = a | b; // Perform a bitwise OR between 'a' and 'b' and store the ‎result in 'result'.‎

^ (Bitwise XOR): Performs a bitwise XOR (exclusive OR) operation on two values.

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result = a ^ b; // Perform a bitwise XOR between 'a' and 'b' and store the ‎result in 'result'.‎

~ (Bitwise NOT): Performs a bitwise NOT (inversion) operation on a value.

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result = ~a; // Invert all bits of 'a' and store the result in 'result'.‎

<< (Bitwise Left Shift): Shifts bits to the left by a specified number.

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result = a << 2; // Left shift 'a' by 2 bits and store the result in 'result'.‎

>> (Bitwise Right Shift): Shifts bits to the right by a specified number.

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result = a >> 3; // Right shift 'a' by 3 bits and store the result in ‎‎'result'.‎

5. Concatenation Operator:

{} (Concatenation): Combines multiple signals or values into a single signal.

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concatenated_signal = {signal_a, signal_b}; // Concatenate 'signal_a' and ‎‎'signal_b' into 'concatenated_signal'.‎

6. Conditional Operator:

? : (Conditional operator): Provides a conditional assignment based on a condition.

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result = (condition) ? value_if_true : value_if_false; // If 'condition' is ‎true, set 'result' to 'value_if_true', otherwise set it to 'value_if_false'.‎

7. Reduction Operators:

& (Reduction AND): Reduces multiple bits to a single bit using logical AND.

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result = &{a, b, c}; // Computes the AND of 'a', 'b', and 'c' and stores the ‎result in 'result'.‎

| (Reduction OR): Reduces multiple bits to a single bit using logical OR.

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result = |{a, b, c}; // Computes the OR of 'a', 'b', and 'c' and stores the ‎result in 'result'.‎

^ (Reduction XOR): Reduces multiple bits to a single bit using logical XOR.

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result = ^{a, b, c}; // Computes the XOR of 'a', 'b', and 'c' and stores the ‎result in 'result'.‎

8. Assignment Operator:

= (Assignment): Assigns a value to a variable or signal.

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variable = value; // Assign 'value' to 'variable'.‎

9. Replication Operator:

{N{value}} (Replication): Replicates a value ‘N’ time to create a larger vector.

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replicated_value = {4{data}}; // Replicate 'data' four times to create ‎‎'replicated_value'.‎

10. Increment and Decrement Operators:

++ (Increment): Adds 1 to the variable.

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a++; // Increment 'a' by 1.‎

-- (Decrement): Subtracts 1 from the variable.

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b--; // Decrement 'b' by 1.‎

11. Logical Implication Operator:

==> (Logical Implication): Computes logical implication between two conditions.

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result = (condition1 ==> condition2); // Set 'result' to 1 if 'condition1' ‎implies 'condition2', 0 otherwise.‎

12. Case Equality Operator:

=== (Case Equality): Compares two values for equality, including "x" and "z" values.

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equal = (a === b); // Set 'equal' to 1 if 'a' and 'b' are equal, including "x" ‎and "z" values, 0 otherwise.‎

13. Case Inequality Operator:

!== (Case Inequality): Compares two values for inequality, including "x" and "z" values.

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not_equal = (a !== b); // Set 'not_equal' to 1 if 'a' and 'b' are not equal, ‎including "x" and "z" values, 0 otherwise.‎

14. Wildcard Equality Operator:

==? (Wildcard Equality): Compares two values for equality, treating "x" and "z" as don't care.

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equal = (a ==? b); // Set 'equal' to 1 if 'a' and 'b' are equal, treating "x" ‎and "z" as don't care, 0 otherwise.‎

In conclusion, Verilog operators are fundamental building blocks for creating hardware descriptions in digital design. They enable you to perform a wide range of operations on data, control logic, and signals within FPGA and ASIC designs. Understanding and effectively using Verilog operators is essential for designing and simulating digital circuits accurately and efficiently.

Key takeaways:

Arithmetic Operators: Perform mathematical calculations such as addition, subtraction, multiplication, division, and modulus.
Relational Operators: Compare values to determine equality, inequality, and relative magnitude.
Logical Operators: Manipulate and evaluate logical conditions using AND, OR, and NOT operations.
Bitwise Operators: Perform operations at the bit level, including AND, OR XOR, and bit shifting.
Concatenation Operator: Combine multiple signals or values into a single signal.
Conditional Operator: Provide conditional assignments based on a specified condition.
Reduction Operators: Reduce multiple bits to a single bit using AND, OR, or XOR operations.
Assignment Operator: Assign values to variables or signals.
Replication Operator: Replicate values to create larger vectors.
Increment and Decrement Operators: Add or subtract from variables.
Logical Implication Operator: Evaluate logical implication between conditions.
Case Equality and Inequality Operators: Compare values for equality and inequality, including "x" and "z" values.
Wildcard Equality Operator: Compare values for equality, treating "x" and "z" as don't care.

These operators provide the flexibility to model a wide range of digital logic and control structures, allowing hardware designers to create complex and efficient digital systems. Whether you're designing simple combinational logic or intricate state machines, Verilog operators are indispensable tools for achieving your hardware design goals.