fuction call within state machine.execution time of function

[chaitu2k]

when u call a function within a state in combinational state machine process block
such as

when s1:
return_value_orsome siganl<= fucntion();
some asssignments;
...
....some more statements
ns<=s2;

how many clock cycles does the fuction take to return a value.....and wht does the function execution time depend on....can anyone pls explain so send a short document

 

[r_e_m_y]

Re: fuction call within state machine.execution time of func

Hi chaitu2k,

I don't think that you can use a synchronous function (that means it contains clocked process = Flip Flop) to affect a signal in an combinatorial process.
The function may only generate combinatorial.
If your signal "return_value_orsome siganl" is clocked somewhere else, the function shall return its value befor the clock edge.
Typically, the function shal work a your global clock frequency. (post synthesis timing report).

be careful if you use different functions to affect your signal "return_value_orsome siganl" in the other states : in synthesis, this will complexify the logic equations, and so you can obtain a very bad maximum frequency value...

I hope this will help you

 

[sarath51]

Re: fuction call within state machine.execution time of func

Function should not have any timing delay etc, so it should get assigned in the same clock cycle