Ripple carry adder in vhdl - vhdl

Question

hi i' trying to do a 4 bit ripple carry adder with VHDL. The problem is that i'm trying to do a testbench to simulate it in ModelSim, but it doesn't work. This is the code and also the code reported by ModelSim:
Full adder code:
library ieee;
use ieee.std_logic_1164.all;
entity fullAdder is
port( -- Input of the full-adder
a : in std_logic;
-- Input of the full-adder
b : in std_logic;
-- Carry input
c_i : in std_logic;
-- Output of the full-adder
o : out std_logic;
-- Carry output
c_o : out std_logic
);
end fullAdder;
architecture data_flow of fullAdder is
begin
o <= a xor b xor c_i;
c_o <= (a and b) or (b and c_i) or (c_i and a);
end data_flow;
Ripple carry adder code:
library ieee;
use ieee.std_logic_1164.all;
entity Ripple_Carry_Adder is
Port (
A: in std_logic_vector (3 downto 0);
B:in std_logic_vector (3 downto 0);
Cin:in std_logic;
S:out std_logic_vector(3 downto 0);
Cout:out std_logic
);
end Ripple_Carry_Adder;
architecture data_flow2 of Ripple_Carry_Adder is
component fullAdder
Port(
A:in std_logic;
B:in std_logic;
Cin:in std_logic;
S:out std_logic;
Cout:out std_logic
);
end component;
signal c1,c2,c3:STD_LOGIC;
begin
FA1:fullAdder port map(A(0),B(0), Cin, S(0), c1);
FA2:fullAdder port map(A(1),B(1), c1, S(1), c2);
FA3:fullAdder port map(A(2),B(2), c2, S(2), c3);
FA4:fullAdder port map(A(3),B(3), c3, S(3), Cout);
end data_flow2;
code of Ripple carry adder testbench:
library IEEE;
use IEEE.STD_LOGIC_1164.ALL;
use IEEE.STD_LOGIC_UNSIGNED.ALL;
use IEEE.NUMERIC_STD.ALL;
ENTITY ripple_carry_adder_tb is
end ripple_carry_adder_tb;
ARCHITECTURE behavior OF ripple_carry_adder_tb is
constant T_CLK : time := 10 ns; -- Clock period
constant T_RESET : time := 25 ns; -- Period before the reset deassertion
COMPONENT Ripple_Carry_Adder
PORT (
A:in std_logic_vector(3 downto 0);
B:in std_logic_vector(3 downto 0);
Cin:in std_logic;
S:out std_logic_vector(3 downto 0);
Cout:out std_logic
);
END COMPONENT;
signal A_tb:std_logic_vector(3 downto 0):="0000";
signal B_tb:std_logic_vector(3 downto 0):="0000";
signal Cin_tb:std_logic:='0';
signal S_tb:std_logic_vector(3 downto 0);
signal Cout_tb:std_logic;
signal clk_tb : std_logic := '0'; -- clock signal, intialized to '0'
signal rst_tb : std_logic := '0'; -- reset signal
signal end_sim : std_logic := '1';
BEGIN
clk_tb <= (not(clk_tb) and end_sim) after T_CLK / 2; -- The clock toggles after T_CLK / 2 when end_sim is high. When end_sim is forced low, the clock stops toggling and the simulation ends.
rst_tb <= '1' after T_RESET;
RP_1: Ripple_Carry_Adder PORT MAP(A=>A_tb,B=>B_tb,Cin=>Cin_tb,S=>S_tb,Cout=>Cout_tb);
d_process: process(clk_tb, rst_tb) -- process used to make the testbench signals change synchronously with the rising edge of the clock
variable t : integer := 0; -- variable used to count the clock cycle after the reset
begin
if(rst_tb = '0') then
A_tb <= "0000";
B_tb <= "0000";
Cin_tb<='0';
t := 0;
elsif(rising_edge(clk_tb)) then
A_tb<=A_tb+1;
B_tb<=B_tb+1;
t := t + 1;
if (t>32) then
end_sim <= '0';
end if;
end if;
end process;
END;
and this is errors reported by ModelSim when i trying to start simulation:
# ** Fatal: (vsim-3817) Port "c_i" of entity "fulladder" is not in the component being instantiated.
# Time: 0 ns Iteration: 0 Instance: /ripple_carry_adder_tb/RP_1/FA1 File:
C:/Users/utente/Desktop/full_adder.vhd Line: 11
# FATAL ERROR while loading design
# Error loading design
Why doesn't work? Thanks