Recursive Function:
Functions are normally used non-recursively. If a function is called concurrently from two locations, both the results are nondeterministic because both calls operate on the same variable space.➢ We used keyword “automatic” to declare a recursive function.
➢ We define the top module and then the function.
➢ A condition is applied that if operand >=2, then fact=fact(operand1)*operand , otherwise fact=1; (this is known as recursive call).
➢ Now, we have to call the function, that is, the number whose factorial we wants to display.
Verilog Code for Recursive Function:
//deine a factorial with recursive fn
module top; //define fn
function automatic integer factorial;
input [31:0] oper;
integer i;
begin
if (oper>=2)
factorial=factorial(oper-1)*oper;
// recursive call
else
factorial=1;
end
endfunction
//call the function
integer result;
initial
begin
result=factorial(7);
$display("factorial of 7 is %0d",result);
end
endmodule
OUTPUT:
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