The multiplication of VHDL is realized by shift and addition. There are many programs on the Internet for reference, such as/blog/static/1348583542009112311635857/

Link is a VHDL program designed by multiplier.

As for the division operation, it is generally realized by looking up a table, taking the reciprocal of the divisor for multiplication, and then doing a one-to-one lookup operation on the divisor and its reciprocal.

In addition, the Internet generally provides some slightly simplified calculation methods, such as DA algorithm, which you can search by yourself.