Arithmetic operators in VHDL - Cheat Sheet & Quick Revision

Recall & Review

beginner

What are the basic arithmetic operators in VHDL?

The basic arithmetic operators in VHDL are:<br>+ (addition), - (subtraction), * (multiplication), / (division), and mod (modulus).

beginner

How do you perform addition of two signals in VHDL?

You use the + operator between two signals of compatible types. For example:<br>result <= a + b;<br>This adds signals 'a' and 'b' and assigns the sum to 'result'.

intermediate

What does the 'mod' operator do in VHDL?

The 'mod' operator returns the remainder after division of one integer by another.<br>Example:<br>7 mod 3 = 1<br>This means 7 divided by 3 leaves a remainder of 1.

intermediate

Can you use arithmetic operators on std_logic_vector directly in VHDL?

No, you cannot use arithmetic operators directly on std_logic_vector.<br>You must first convert them to a numeric type like integer or unsigned before performing arithmetic.

advanced

What happens if you divide by zero in VHDL arithmetic?

Dividing by zero causes a runtime error or simulation failure.<br>Always ensure the divisor is not zero before division to avoid errors.

Which operator in VHDL gives the remainder of a division?

A /

B *

C mod

D -

The 'mod' operator returns the remainder after division.

What operator would you use to multiply two integers in VHDL?

A +

B *

C -

D /

The '*' operator multiplies two numbers.

Can you directly add two std_logic_vector signals using '+' in VHDL?

A No, you must convert them first

B Only if they are unsigned

C Only if they are the same length

D Yes, always

You must convert std_logic_vector to a numeric type before arithmetic.

What will happen if you divide by zero in VHDL?

A It rounds to nearest integer

B Result is infinity

C Result is zero

D Runtime error or simulation failure

Division by zero causes an error or simulation failure.

Which operator subtracts one number from another in VHDL?

A -

B +

C *

D /

The '-' operator subtracts numbers.

Explain how to perform arithmetic operations on signals in VHDL and any type considerations.

Think about the types and operators you use.

Describe the difference between '/' and 'mod' operators in VHDL.

One gives quotient, the other remainder.