src/parser.vhd

   1 library ieee;
   2 use ieee.std_logic_1164.all;
   3 use ieee.numeric_std.all;
   4 use work.gen_pkg.all;
   5
   6 entity parser is
   7         port
   8         (
   9                 sys_clk : in std_logic;
  10                 sys_res_n : in std_logic;
  11                 -- History
  12                 p_rw : out std_logic;
  13                 p_spalte : out hspalte;
  14                 p_rget : out std_logic;
  15                 p_rdone : in std_logic;
  16                 p_read : in hbyte;
  17                 p_wtake : out std_logic;
  18                 p_wdone : in std_logic;
  19                 p_write : out hbyte;
  20                 p_finished : out std_logic;
  21                 -- ALU
  22                 opcode : out alu_ops;
  23                 op1 : out csigned;
  24                 op2 : out csigned;
  25                 op3 : in csigned;
  26                 do_calc : out std_logic;
  27                 calc_done : in std_logic;
  28                 -- TODO: calc_error : in std_logic;
  29                 -- Scanner
  30                 do_it : in std_logic;
  31                 finished : out std_logic
  32         );
  33 end entity parser;
  34
  35 architecture beh of parser is
  36         type PARSER_STATE is (SIDLE, SREAD_CHAR1, SREAD_CHAR2, SWRITE_CHAR);
  37         signal state_int, state_next : PARSER_STATE;
  38         signal z_int, z_next : csigned;
  39         signal rbyte_int, rbyte_next : hbyte;
  40         signal p_write_int, p_write_next : hbyte;
  41         signal p_rget_int, p_rget_next : std_logic;
  42         signal p_wtake_int, p_wtake_next : std_logic;
  43         signal p_finished_int, p_finished_next : std_logic;
  44 begin
  45         p_write <= p_write_int;
  46         p_rget <= p_rget_int;
  47         p_wtake <= p_wtake_int;
  48         p_finished <= p_finished_int;
  49
  50         process(sys_clk, sys_res_n)
  51         begin
  52                 if sys_res_n = '0' then
  53                         state_int <= SIDLE;
  54                         z_int <= (others => '0');
  55                         rbyte_int <= (others => '0');
  56                         -- out ports
  57                         p_rw <= '0';
  58                         p_spalte <= (others => '0');
  59                         p_rget_int <= '0';
  60                         p_write_int <= (others => '0');
  61                         p_wtake_int <= '0';
  62                         p_finished_int <= '0';
  63                         opcode <= ALU_NOP;
  64                         op1 <= (others => '0');
  65                         op2 <= (others => '0');
  66                         do_calc <= '0';
  67                         finished <= '0';
  68                 elsif rising_edge(sys_clk) then
  69                         -- internal
  70                         state_int <= state_next;
  71                         z_int <= z_next;
  72                         rbyte_int <= rbyte_next;
  73                         -- out ports
  74                         p_rget_int <= p_rget_next;
  75                         p_write_int <= p_write_next;
  76                         p_wtake_int <= p_wtake_next;
  77                         p_finished_int <= p_finished_next;
  78                 end if;
  79         end process;
  80
  81         -- next state
  82         process(state_int, do_it, p_rdone, p_wdone, p_read)
  83         begin
  84                 state_next <= state_int;
  85
  86                 case state_int is
  87                         when SIDLE =>
  88                                 if do_it = '1' then
  89                                         state_next <= SREAD_CHAR1;
  90                                 end if;
  91                         when SREAD_CHAR1 =>
  92                                 if p_rdone = '1' then
  93                                         state_next <= SREAD_CHAR2;
  94                                 end if;
  95                         when SREAD_CHAR2 =>
  96                                 if p_wdone = '1' then
  97                                         state_next <= SWRITE_CHAR;
  98                                 end if;
  99                         when SWRITE_CHAR =>
 100                                 if rbyte_int = hbyte(to_unsigned(character'pos(character'val(0)), 8)) then
 101                                         if do_it = '0' then
 102                                                 state_next <= SIDLE;
 103                                         end if;
 104                                 else
 105                                         state_next <= SREAD_CHAR1;
 106                                 end if;
 107                 end case;
 108         end process;
 109
 110         process(state_int, p_read, p_write_int, z_int, rbyte_int, p_rget_int)
 111         begin
 112                 -- internal
 113                 z_next <= z_int;
 114                 rbyte_next <= rbyte_int;
 115                 -- signals
 116                 p_rget_next <= '0';
 117                 p_write_next <= p_write_int;
 118                 p_wtake_next <= '0';
 119                 p_finished_next <= '0';
 120
 121                 case state_int is
 122                         when SIDLE =>
 123                                 z_next <= (others => '0');
 124                                 rbyte_next <= (others => '0');
 125                                 p_write_next <= (others => '0');
 126                         when SREAD_CHAR1 =>
 127                                 p_rget_next <= '1';
 128                                 p_write_next <= (others => '0');
 129                         when SREAD_CHAR2 =>
 130                                 rbyte_next <= p_read;
 131                                 p_wtake_next <= '1';
 132                                 p_write_next <= p_read;
 133                         when SWRITE_CHAR =>
 134                                 if rbyte_int = hbyte(to_unsigned(character'pos(character'val(0)), 8)) then
 135                                         p_finished_next <= '1';
 136                                 end if;
 137                 end case;
 138         end process;
 139 end architecture beh;