cpu/src/writeback_stage_b.vhd

   1 library IEEE;
   2 use IEEE.std_logic_1164.all;
   3 use IEEE.numeric_std.all;
   4
   5 use work.common_pkg.all;
   6 use work.core_pkg.all;
   7
   8 use work.mem_pkg.all;
   9 use work.extension_pkg.all;
  10
  11 architecture behav of writeback_stage is
  12
  13 signal data_ram_read : word_t;
  14
  15 signal wb_reg, wb_reg_nxt : writeback_rec;
  16
  17 signal ext_uart,ext_timer,ext_gpmp :  extmod_rec;
  18
  19
  20
  21 begin
  22
  23
  24         data_ram : r_w_ram
  25                 generic map (
  26                         DATA_ADDR_WIDTH,
  27                         WORD_WIDTH
  28                 )
  29
  30                 port map (
  31                         clk,
  32                         wb_reg_nxt.address(DATA_ADDR_WIDTH+1 downto 2),
  33                         wb_reg_nxt.address(DATA_ADDR_WIDTH+1 downto 2),
  34                         wb_reg_nxt.dmem_write_en,
  35                         ram_data,
  36                         data_ram_read
  37                 );
  38
  39
  40 syn: process(clk, reset)
  41
  42 begin
  43
  44         if (reset = RESET_VALUE) then
  45                 wb_reg.address <= (others => '0');
  46                 wb_reg.dmem_en <= '0';
  47                 wb_reg.dmem_write_en <= '0';
  48                 wb_reg.hword <= '0';
  49                 wb_reg.byte_s <= '0';
  50         elsif rising_edge(clk) then
  51                 wb_reg <= wb_reg_nxt;
  52         end if;
  53
  54 end process;
  55
  56 --      type writeback_rec is record
  57 --              address : in word_t;            --ureg
  58 --              dmem_en : in std_logic;         --ureg (jump addr in mem or in address)
  59 --              dmem_write_en : in std_logic;   --ureg
  60 --              hword_hl : in std_logic         --ureg
  61 --      end record;
  62
  63
  64
  65 shift_input: process(data_ram_read, address, dmem_en, dmem_write_en, hword, wb_reg, result, byte_s, alu_jmp, br_pred)
  66
  67 begin
  68         wb_reg_nxt.address <= address;
  69         wb_reg_nxt.dmem_en <= dmem_en;
  70         wb_reg_nxt.dmem_write_en <= dmem_write_en;
  71         wb_reg_nxt.hword <= hword;
  72         wb_reg_nxt.byte_s <= byte_s;
  73
  74         regfile_val <= result; --(others => '0');
  75
  76         if (wb_reg.dmem_en = '1' and wb_reg.dmem_write_en = '0') then   -- ram read operation --alu_jmp = '0' and
  77                 regfile_val <= data_ram_read;
  78                 if (wb_reg.hword = '1') then
  79                         regfile_val <= (others => '0');
  80                         if (wb_reg.address(1) = '1') then
  81                                 regfile_val(15 downto 0) <= data_ram_read(31 downto 16);
  82                         else
  83                                 regfile_val(15 downto 0) <= data_ram_read(15 downto 0);
  84                         end if;
  85                 end if;
  86                 if (wb_reg.byte_s = '1') then
  87                         regfile_val <= (others => '0');
  88                         case wb_reg.address(1 downto 0) is
  89                                 when "00" => regfile_val(7 downto 0) <= data_ram_read(7 downto 0);
  90                                 when "01" => regfile_val(7 downto 0) <= data_ram_read(15 downto 8);
  91                                 when "10" => regfile_val(7 downto 0) <= data_ram_read(23 downto 16);
  92                                 when "11" => regfile_val(7 downto 0) <= data_ram_read(31 downto 24);
  93                                 when others => null;
  94                         end case;
  95                 end if;
  96         end if;
  97
  98         --jump <= (alu_jmp xor br_pred) and (write_en or wb_reg.dmem_en);
  99         jump <= (alu_jmp xor br_pred);-- and (write_en or wb_reg.dmem_en);
 100
 101 --      if alu_jmp = '0' and br_pred = '1' and write_en = '0' then
 102 --              jump <= '1';
 103 --      end if;
 104
 105         jump_addr <= result;
 106         if ((alu_jmp and wb_reg.dmem_en) = '1') then
 107                 jump_addr <= data_ram_read;
 108         end if;
 109
 110 end process;
 111
 112 --                      result : in gp_register_t;      --reg  (alu result or jumpaddr)
 113 --                      result_addr : in gp_addr_t;     --reg
 114 --                      address : in word_t;            --ureg
 115 --                      alu_jmp : in std_logic;         --reg
 116 --                      br_pred : in std_logic;         --reg
 117 --                      write_en : in std_logic;        --reg  (register file)
 118 --                      dmem_en : in std_logic;         --ureg (jump addr in mem or in result)
 119 --                      dmem_write_en : in std_logic;   --ureg
 120 --                      hword : in std_logic            --ureg
 121
 122
 123
 124 out_logic: process(write_en, result_addr, wb_reg, alu_jmp)
 125
 126 begin
 127         reg_we <= (write_en or (wb_reg.dmem_en and not(wb_reg.dmem_write_en))) and not(alu_jmp);
 128         reg_addr <= result_addr;
 129 end process;
 130
 131
 132 addr_de_mult: process(wb_reg_nxt.address, ram_data, wb_reg)
 133
 134 begin
 135
 136   ext_uart.sel <='0';
 137   ext_uart.wr_en <= '0';
 138   ext_uart.byte_en <= (others => '0');
 139   ext_uart.data <= (others => '0');
 140   ext_uart.addr <= (others => '0');
 141
 142   ext_timer.sel <='0';
 143   ext_timer.wr_en <= '0';
 144   ext_timer.byte_en <= (others => '0');
 145   ext_timer.data <= (others => '0');
 146   ext_timer.addr <= (others => '0');
 147
 148   ext_gpmp.sel <='0';
 149   ext_gpmp.wr_en <= '0';
 150   ext_gpmp.byte_en <= (others => '0');
 151   ext_gpmp.data <= (others => '0');
 152   ext_gpmp.addr <= (others => '0');
 153                                                  -- wenn ich hier statt dem 4rer die konstante nehme dann gibts an fehler wegen nicht lokaler variable -.-
 154  case wb_reg_nxt.address(wb_reg_nxt.address'high downto 4) is
 155         when EXT_UART_ADDR =>
 156                 ext_uart.sel <='1';
 157                 ext_uart.wr_en <= wb_reg_nxt.dmem_write_en;
 158                 ext_uart.data <= ram_data;
 159                 ext_uart.addr <= wb_reg_nxt.address(wb_reg_nxt.address'high downto BYTEADDR);
 160                 case wb_reg.address(1 downto 0) is
 161                                 when "00" => ext_uart.byte_en <= "0001";
 162                                 when "01" => ext_uart.byte_en <= "0010";
 163                                 when "10" => ext_uart.byte_en <= "0100";
 164                                 when "11" => ext_uart.byte_en <= "1000";
 165                                 when others => null;
 166                         end case;
 167         when EXT_TIMER_ADDR =>
 168                 ext_timer.sel <='1';
 169                 ext_timer.wr_en <= wb_reg_nxt.dmem_write_en;
 170                 ext_timer.data <= ram_data;
 171                 ext_timer.addr <= wb_reg_nxt.address(wb_reg_nxt.address'high downto BYTEADDR);
 172                 case wb_reg.address(1 downto 0) is
 173                                 when "00" => ext_timer.byte_en <= "0001";
 174                                 when "01" => ext_timer.byte_en <= "0010";
 175                                 when "10" => ext_timer.byte_en <= "0100";
 176                                 when "11" => ext_timer.byte_en <= "1000";
 177                                 when others => null;
 178                         end case;
 179         when EXT_GPMP_ADDR =>
 180                 ext_gpmp.sel <='1';
 181                 ext_gpmp.wr_en <= wb_reg_nxt.dmem_write_en;
 182                 ext_gpmp.data <= ram_data;
 183                 ext_gpmp.addr <= wb_reg_nxt.address(wb_reg_nxt.address'high downto BYTEADDR);
 184                 case wb_reg.address(1 downto 0) is
 185                                 when "00" => ext_gpmp.byte_en <= "0001";
 186                                 when "01" => ext_gpmp.byte_en <= "0010";
 187                                 when "10" => ext_gpmp.byte_en <= "0100";
 188                                 when "11" => ext_gpmp.byte_en <= "1000";
 189                                 when others => null;
 190                         end case;
 191         -- hier kann man weiter extensions adden :) Konstanten sind im extension pkg definiert
 192         when others => null;
 193  end case;
 194
 195 end process;
 196
 197 end behav;
 198