step time simulation

library ieee;

use ieee.std_logic_1164 .all;

use ieee.std_logic_arith.all;

use ieee.std_logic_unsigned.all;

use ieee.math_real.all;

entity triangle_generator is

 generic(AMP: real;

  OFFSET: real;

  FREQ: real;

  PHASE :real);

 port(wave1: out real);

end triangle_generator;

architecture archi of triangle_generator is

signal tmp1 : real := 0.0;

begin

 P1:process

 constant delta   : real := 1000.0e-12;

 constant fin  : time := 1000 ps;

 variable angle   : real := 0.0;

 variable t    : real := 0.0;

 variable PHASE_RAD : real := 0.0;

 begin

   PHASE_RAD := (math_2_pi * PHASE)/360.0;

  loop

   angle   := math_2_pi * FREQ * t;

   t := t + delta;

   tmp1 <= OFFSET+(AMP/2.0)*(2.0/math_pi)*arcsin(sin(angle));

   wait for fin;

  end loop;

  wait;

 end process P1;

 wave1 <= tmp1;

end archi;