hw/measurement_register.vhd

   1 library ieee;
   2 use ieee.std_logic_1164.all;
   3 use ieee.std_logic_arith.all;
   4 use ieee.std_logic_unsigned.all;
   5 use ieee.numeric_std.all;
   6 use work.lx_rocon_pkg.all;
   7
   8 -- Transaction measurement register
   9
  10 entity measurement_register is
  11         generic
  12         (
  13                 id_g   : std_logic_vector(31 downto 0) := (others => '0')
  14         );
  15         port
  16         (
  17                 -- Clock
  18                 clk_i    : in std_logic;
  19                 -- Reset
  20                 reset_i  : in std_logic;
  21                 -- Chip enable
  22                 ce_i     : in std_logic;
  23                 -- Switch
  24                 switch_i : in std_logic;
  25                 -- Data bus
  26                 data_i   : in std_logic_vector(31 downto 0);
  27                 data_o   : out std_logic_vector(31 downto 0);
  28                 -- Bus signals
  29                 bls_i    : in std_logic_vector(3 downto 0)
  30         );
  31 end measurement_register;
  32
  33 architecture Behavioral of measurement_register is
  34         signal value_s : std_logic_vector(31 downto 0);
  35 begin
  36
  37         data_o <= value_s when switch_i = '1' else id_g;
  38
  39 -- Write waits for clock
  40 memory_bus_write:
  41         process
  42         begin
  43
  44                 wait until clk_i'event and clk_i = '1';
  45
  46                 if reset_i = '1' then
  47                         value_s <= (others => '0');
  48                 else
  49
  50                         if ce_i = '1' and bls_i /= "0000" then
  51
  52                                 if bls_i(0) = '1' then
  53                                         value_s(7 downto 0)   <= data_i(7 downto 0);
  54                                 end if;
  55                                 if bls_i(1) = '1' then
  56                                         value_s(15 downto 8)  <= data_i(15 downto 8);
  57                                 end if;
  58                                 if bls_i(2) = '1' then
  59                                         value_s(23 downto 16) <= data_i(23 downto 16);
  60                                 end if;
  61                                 if bls_i(3) = '1' then
  62                                         value_s(31 downto 24) <= data_i(31 downto 24);
  63                                 end if;
  64
  65                         end if;
  66                 end if;
  67
  68         end process;
  69
  70 end Behavioral;
  71