Verilog Combinational Logic

Combinational logic refers to digital logic circuits where the output depends only on the current input values. Verilog provides several constructs for describing combinational logic circuits.

The most common way to describe combinational logic in Verilog is by using the assign statement. The assign statement is used to create a connection between a signal and an expression. Here is an example of an assign statement:

assign out = a & b;

In this example, the output signal "out" is assigned the value of the logical AND of the input signals "a" and "b". The assign statement creates a continuous assignment between the output signal and the expression on the right-hand side of the statement.

Verilog also provides several operators for performing logical, arithmetic, and bitwise operations on signals and expressions. Here are some examples of Verilog operators:

- Logical AND: `&`
- Logical OR: `|`
- Logical NOT: `!`
- Bitwise AND: `&`
- Bitwise OR: `|`
- Bitwise NOT: `

`
– Addition: `+`
– Subtraction: `-`
– Multiplication: `*`
– Division: `/`
– Modulus: `%`
– Equality: `==`
– Inequality: `!=`
– Greater than: `>`
– Less than: `<` - Conditional operator: `? :` Here is an example of a Verilog module that implements a 2-to-1 multiplexer using combinational logic:

module mux2to1 (
  input sel,
  input a,
  input b,
  output out
);

  assign out = sel ? b : a;

endmodule

In this example, the module has three input ports “sel”, “a”, and “b”, and one output port “out”. The output signal “out” is assigned the value of “a” or “b”, depending on the value of the select signal “sel”.

By using Verilog constructs for combinational logic, designers can create complex digital circuits that perform a variety of logical and arithmetic operations. Understanding combinational logic in Verilog is essential for designing and describing the behavior of digital circuits.