diff --git a/reg_tb.vhdl b/reg_tb.vhdl
new file mode 100644
index 0000000..c6ebd3e
--- /dev/null
+++ b/reg_tb.vhdl
@@ -0,0 +1,188 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
+use ieee.math_real.uniform;
+use ieee.math_real.floor;
+
+entity reg_tb is
+end reg_tb;
+
+architecture Structurel of reg_tb is
+
+    -- useful stuff
+    function bit_to_integer (s : std_logic) return integer is
+    begin
+    if s = '1' then
+      return 1;
+    else
+      return 0;
+    end if;
+    end function;
+
+
+    -- port 1 write priority
+    signal wdata1_tb : std_logic_vector(31 downto 0);
+    signal wadr1_tb  : std_logic_vector(3 downto 0);
+    signal wen1_tb   : std_logic;
+
+    -- port 2 write
+    signal wdata2_tb : std_logic_vector(31 downto 0);
+    signal wadr2_tb  : std_logic_vector(3 downto 0);
+    signal wen2_tb   : std_logic;
+
+    -- write cspr port
+    signal wcry_tb    : std_logic; -- write c
+    signal wzero_tb   : std_logic; -- write z
+    signal wneg_tb    : std_logic; -- write n
+    signal wovr_tb    : std_logic; -- write v
+    signal cspr_wb_tb : std_logic; -- write write back
+
+    -- read port 1 32 bits
+    signal reg_rd1_tb : std_logic_vector(31 downto 0);
+    signal radr1_tb   : std_logic_vector(3 downto 0); --
+    signal reg_v1_tb  : std_logic;
+
+    -- read port 2 32 bits
+    signal reg_rd2_tb : std_logic_vector(31 downto 0);
+    signal radr2_tb   : std_logic_vector(3 downto 0);
+    signal reg_v2_tb  : std_logic;
+
+    -- read port 3 32 bits
+    signal reg_rd3_tb : std_logic_vector(31 downto 0);
+    signal radr3_tb   : std_logic_vector(3 downto 0);
+    signal reg_v3_tb  : std_logic;
+
+    -- read cspr port
+    signal reg_cry_tb  : std_logic;-- read c
+    signal reg_zero_tb : std_logic;-- read z
+    signal reg_neg_tb  : std_logic;-- read n
+    signal reg_cznv_tb : std_logic;-- read czn validity
+    signal reg_ovr_tb  : std_logic;-- read v
+    signal reg_vv_tb   : std_logic;-- read v validity
+
+    -- invalidate port 
+    signal inval_adr1_tb : std_logic_vector(3 downto 0);
+    signal inval1_tb     : std_logic;
+
+    signal inval_adr2_tb : std_logic_vector(3 downto 0);
+    signal inval2_tb     : std_logic;
+
+    signal inval_czn_tb : std_logic;
+    signal inval_ovr_tb : std_logic;
+
+    -- pc
+    signal reg_pc_tb  : std_logic_vector(31 downto 0);
+    signal reg_pcv_tb : std_logic;
+    signal inc_pc_tb  : std_logic;
+
+    -- global interface
+    signal ck_tb      : std_logic;
+    signal reset_n_tb : std_logic;
+    signal vdd_tb     : bit;
+    signal vss_tb     : bit;
+
+begin
+    reg_0 : entity work.reg(behavioral)
+        port map(
+            -- write port 1 priority
+            wdata1 => wdata1_tb;
+            wadr1  => wadr1_tb;
+            wen1   => wen1_tb;
+            
+            -- write port 2
+            wdata2 => wdata2_tb;
+            wadr2  => wadr2_tb;
+            wen2   => wen2_tb;
+            
+            -- write cspr port
+            wcry    => wcry_tb;
+            wzero   => wzero_tb;
+            wneg    => wneg_tb;
+            wovr    => wovr_tb;
+            cspr_wb => cspr_wb_tb;
+            
+            -- read port 1 32 bits
+            reg_rd1 => reg_rd1_tb;
+            radr1   => radr1_tb;
+            reg_v1  => reg_v1_tb;
+            
+            -- read port 2 32 bits
+            reg_rd2 => reg_rd2_tb;
+            radr2   => radr2_tb;
+            reg_rd1_tb
+            reg_v2 => reg_v2_tb;
+            
+            -- read port 3 32 bits
+            reg_rd3 => reg_rd3_tb;
+            radr3   => radr3_tb;
+            reg_v3  => reg_v3_tb;
+            
+            -- read cspr port
+            reg_cry  => reg_cry_tb;
+            reg_zero => reg_zero_tb;
+            reg_neg  => reg_neg_tb;
+            reg_cznv => reg_cznv_tb;
+            reg_ovr  => reg_ovr_tb;
+            reg_vv   => reg_vv_tb;
+            
+            -- invalidate port 
+            inval_adr1 => inval_adr1_tb;
+            inval1     => inval1_tb;
+
+            inval_adr2 => inval_adr2_tb;
+            inval2     => inval2_tb;
+
+            inval_czn => inval_czn_tb;
+            inval_ovr => inval_ovr_tb;
+            -- pc
+            reg_pc  => reg_pc_tb;
+            reg_pcv => reg_pcv_tb;
+            inc_pc  => inc_pc_tb;
+            
+            -- global interface
+            ck      => ck_tb;
+            reset_n => reset_n_tb;
+            vdd     => vdd_tb;
+            vss     => vss_tb
+        );
+
+    process
+        variable seed1 : positive;
+        variable seed2 : positive;
+        variable x     : real;
+        variable y     : integer;
+
+    begin
+
+        vdd_tb <= '1';
+        vss_tb <= '0';
+        reset_n_tb <= '1';
+        
+        -- init clock
+        ck_tb <= '0';
+        
+        -- set seeds for random number
+        seed1 := 1;
+        seed2 := 1;
+        wait for 1 ns;
+
+        reset_n_tb <= '0';
+        ck_tb      <= '1';
+        wait for 1 ns;
+
+        for_registers : for i in 0 to 15 loop
+            radr1_tb <= std_logic_vector(to_unsigned(i, radr1_tb'length));
+            report "[debug] radr1_tb = " & integer'image(to_integer(unsigned(radr1_tb)));
+            radr2_tb <= std_logic_vector(to_unsigned(i, radr2_tb'length));
+            radr3_tb <= std_logic_vector(to_unsigned(i, radr3_tb'length));
+        end loop for_registers;
+        
+        wait for 1 ns;
+        
+        assert (bit_to_integer(v_tb) = bit_to_integer(vv)) report "reg_tb: [error] in v flag" severity error;
+        
+        wait;
+    end process;
+end structurel;
+