mips_sys

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
LIBRARY ieee;
USE ieee.std_logic_1164.all;
USE ieee.numeric_std.all;
USE work.mips_types.all;
ENTITY e_mips_decoder IS
    PORT (
        i_instr:  IN  std_logic_vector(31 DOWNTO 0);
        o_reg_s:  OUT std_logic_vector( 4 DOWNTO 0);
        o_reg_t:  OUT std_logic_vector( 4 DOWNTO 0);
        o_reg_d:  OUT std_logic_vector( 4 DOWNTO 0);
        o_imm_a:  OUT std_logic_vector( 4 DOWNTO 0);
        o_imm_16: OUT std_logic_vector(15 DOWNTO 0);
        o_imm_26: OUT std_logic_vector(25 DOWNTO 0);
        o_op:     OUT t_op;
        o_link:   OUT t_link;
        o_cmp:    OUT t_cmp;
        o_alu:    OUT t_alu;
        o_imm:    OUT t_imm;
        o_ldst:   OUT t_ldst
    );
END ENTITY e_mips_decoder;
ARCHITECTURE a_mips_decoder OF e_mips_decoder IS
    TYPE t_enc_type IS (enc_reg, enc_imm, enc_jmp);
    SIGNAL s_opcode:   std_logic_vector(5 DOWNTO 0);
    SIGNAL s_ext_op:   std_logic_vector(4 DOWNTO 0);
    SIGNAL s_func:     std_logic_vector(5 DOWNTO 0);
    SIGNAL s_enc_type: t_enc_type;
BEGIN
    s_opcode <= i_instr(31 DOWNTO 26);
    s_ext_op <= i_instr(20 DOWNTO 16);
    s_func   <= i_instr( 5 DOWNTO  0);
    p_enc_type: PROCESS(s_opcode)
    BEGIN
        CASE s_opcode IS
            WHEN "000000" => s_enc_type <= enc_reg;
            WHEN "000010" => s_enc_type <= enc_jmp;
            WHEN "000011" => s_enc_type <= enc_jmp;
            WHEN OTHERS   => s_enc_type <= enc_imm;
        END CASE;
    END PROCESS p_enc_type;
    p_reg_s: PROCESS(i_instr, s_enc_type)
    BEGIN
        CASE s_enc_type IS
 
 
הההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההההה
XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX