cr_file.vhdl

   1 library ieee;
   2 use ieee.std_logic_1164.all;
   3 use ieee.numeric_std.all;
   4
   5 library work;
   6 use work.common.all;
   7
   8 entity cr_file is
   9     port(
  10         clk   : in std_logic;
  11
  12         d_in  : in Decode2ToCrFileType;
  13         d_out : out CrFileToDecode2Type;
  14
  15         w_in  : in WritebackToCrFileType
  16         );
  17 end entity cr_file;
  18
  19 architecture behaviour of cr_file is
  20     signal crs : std_ulogic_vector(31 downto 0) := (others => '0');
  21     signal crs_updated : std_ulogic_vector(31 downto 0);
  22     signal xerc : xer_common_t := xerc_init;
  23     signal xerc_updated : xer_common_t;
  24 begin
  25     cr_create_0: process(all)
  26         variable hi, lo : integer := 0;
  27         variable cr_tmp : std_ulogic_vector(31 downto 0) := (others => '0');
  28     begin
  29         cr_tmp := crs;
  30
  31         for i in 0 to 7 loop
  32             if w_in.write_cr_mask(i) = '1' then
  33                 lo := i*4;
  34                 hi := lo + 3;
  35                 cr_tmp(hi downto lo) := w_in.write_cr_data(hi downto lo);
  36             end if;
  37         end loop;
  38
  39         crs_updated <= cr_tmp;
  40
  41         if w_in.write_xerc_enable = '1' then
  42             xerc_updated <= w_in.write_xerc_data;
  43         else
  44             xerc_updated <= xerc;
  45         end if;
  46
  47     end process;
  48
  49     -- synchronous writes
  50     cr_write_0: process(clk)
  51     begin
  52         if rising_edge(clk) then
  53             if w_in.write_cr_enable = '1' then
  54                 report "Writing " & to_hstring(w_in.write_cr_data) & " to CR mask " & to_hstring(w_in.write_cr_mask);
  55                 crs <= crs_updated;
  56             end if;
  57             if w_in.write_xerc_enable = '1' then
  58                 report "Writing XERC";
  59                 xerc <= xerc_updated;
  60             end if;
  61         end if;
  62     end process;
  63
  64     -- asynchronous reads
  65     cr_read_0: process(all)
  66     begin
  67         -- just return the entire CR to make mfcrf easier for now
  68         if d_in.read = '1' then
  69             report "Reading CR " & to_hstring(crs_updated);
  70         end if;
  71         d_out.read_cr_data <= crs_updated;
  72         d_out.read_xerc_data <= xerc_updated;
  73     end process;
  74 end architecture behaviour;