title: can I know how long time e.g addition insturction take in vhdl code result<a+b ;?
body: <p>how can I  know addition instruction or subtraction e.g result&lt;= a+b ; how long time it takes in vhdl?
  I am trying to measure the instruction time for ALU , each instruction addition , multiplication and other ALU instructions, please can any one help me? I used now time but it doesn't change the answer it always be the same for all operations </p>