--
-- Dalton Project
-- Roman Lysecky and Puneet Mehra
-- 07/14/98
-- Version 1.2
-- Notes: Only a subset of MIPS instructions have been implemented.
-- Instruction do not follow the correct MIPS format.
--
--**************************************************************************--
library IEEE;
use IEEE.STD_LOGIC_1164.all;
use IEEE.STD_LOGIC_ARITH.all;
--**************************************************************************--
entity MIPS is
port( clk : in STD_LOGIC;
rst : in STD_LOGIC;
cs : in STD_LOGIC;
data : inout UNSIGNED(31 downto 0);
addr : out UNSIGNED(22 downto 0);
rd : out STD_LOGIC;
wr : out STD_LOGIC;
rdy : in STD_LOGIC;
adr : out UNSIGNED(31 downto 0) );
end MIPS;
--**************************************************************************--
architecture BHV_MIPS of MIPS is
--
-- type declarations
--
subtype REG_TYPE is UNSIGNED(31 downto 0);
type REG_FILE_TYPE is array(0 to 31) of REG_TYPE;
type STATE_TYPE is ( IF_S, IF2_S, IF3_S, IDE_S, MEM_S, MEM_READ1_S,
MEM_READ2_S, WB_S );
--
-- constant declarations
--
constant Z_32 : UNSIGNED(31 downto 0) :=
"ZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZZ";
constant Z_23 : UNSIGNED(22 downto 0) :=
"ZZZZZZZZZZZZZZZZZZZZZZZ";
constant C0_32 : UNSIGNED(31 downto 0) :=
"00000000000000000000000000000000";
constant C0_23 : UNSIGNED(22 downto 0) :=
"00000000000000000000000";
constant C1_32 : UNSIGNED(31 downto 0) :=
"00000000000000000000000000000001";
constant C1_23 : UNSIGNED(22 downto 0) :=
"00000000000000000000001";
constant C14_23 : UNSIGNED(22 downto 0) :=
"00000000000000000001110";
constant C4_32 : UNSIGNED(31 downto 0) :=
"00000000000000000000000000000100";
constant C2P1B_32 : UNSIGNED(31 downto 0) :=
"10000000000000000000000000000000";
constant LI : UNSIGNED(3 downto 0) := "0000";
constant MOV : UNSIGNED(3 downto 0) := "0001";
constant LOAD : UNSIGNED(3 downto 0) := "0010";
constant STORE : UNSIGNED(3 downto 0) := "0011";
constant GE : UNSIGNED(3 downto 0) := "0100";
constant JNZ : UNSIGNED(3 downto 0) := "0101";
constant ADD : UNSIGNED(3 downto 0) := "0110";
constant JMP : UNSIGNED(3 downto 0) := "0111";
constant NOP : UNSIGNED(3 downto 0) := "1000";
constant SHFL : UNSIGNED(3 downto 0) := "1001";
constant SHFR : UNSIGNED(3 downto 0) := "1010";
constant EQ : UNSIGNED(3 downto 0) := "1011";
constant STOREI : UNSIGNED(3 downto 0) := "1100";
--
-- signal declarations
--
signal state : STATE_TYPE;
signal reg_file : REG_FILE_TYPE;
signal pc_reg : UNSIGNED(22 downto 0);
signal inst_reg : REG_TYPE;
signal reg_write, mem_write, mem_read : STD_LOGIC;
signal reg_data, mem_data : UNSIGNED(31 downto 0);
signal mem_addr : UNSIGNED(22 downto 0);
signal reg_num : UNSIGNED(4 downto 0);
signal init : STD_LOGIC;
begin
process(clk, rst, cs, init)
variable reg_data1,
reg_data2, add_result : UNSIGNED(31 downto 0);
begin
if( rst = '1' ) then
state <= IF_S;
data <= Z_32;
addr <= Z_23;
rd <= 'Z';
wr <= 'Z';
init <= '0';
pc_reg <= C0_23;
reg_file(0) <= C0_32;
reg_data1 := C0_32;
reg_data2 := C0_32;
add_result := C0_32;
adr <= add_result;
elsif( cs = '0' ) then
state <= IF_S;
data <= Z_32;
addr <= Z_23;
rd <= 'Z';
wr <= 'Z';
init <= '1';
adr <= add_result;
elsif( cs = '1' and init = '1' ) then
--
-- capture state
--
data <= Z_32;
addr <= C0_23;
rd <= '0';
wr <= '0';
init <= '0';
state <= IF_S;
adr <= add_result;
elsif( clk'event and clk = '1' ) then
--
-- steady state
--
data <= Z_32;
addr <= Z_23;
rd <= '0';
wr <= '0';
adr <= add_result;
case( state ) is
when IF_S =>
reg_write <= '0';
mem_write <= '0';
mem_read <= '0';
if( rdy = '1' ) then
addr <= pc_reg;
data <= Z_32;
rd <= '1';
state <= IF2_S;
else
state <= IF_S;
end if;
when IF2_S =>
reg_write <= '0';
mem_write <= '0';
mem_read <= '0';
state <= IF3_S;
when IF3_S =>
reg_write <= '0';
mem_write <= '0';
mem_read <= '0';
if( rdy = '1' ) then
inst_reg <= data;
pc_reg <= pc_reg + C1_23;
state <= IDE_S;
else
state <= IF3_S;
end if;
when IDE_S =>
reg_write <= '0';
mem_write <= '0';
mem_read <= '0';
case( inst_reg(31 downto 28) ) is
when LI =>
reg_write <= '1';
mem_write <= '0';
mem_read <= '0';
reg_data <= "000000000"
& inst_reg(22 downto 0);
reg_num <= inst_reg(27 downto 23);
state <= MEM_S;
when MOV =>
reg_write <= '1';
mem_write <= '0';
mem_read <= '0';
reg_data <= reg_file(
conv_integer(inst_reg(22 downto 18)));
reg_num <= inst_reg(27 downto 23);
state <= MEM_S;
when LOAD =>
reg_write <= '1';
mem_write <= '0';
mem_read <= '1';
reg_num <= inst_reg(27 downto 23);
mem_addr <= inst_reg(22 downto 0);
state <= MEM_S;
when STORE =>
reg_write <= '0';
mem_write <= '1';
mem_read <= '0';
mem_addr <= inst_reg(22 downto 0);
mem_data <= reg_file(
conv_integer(inst_reg(27 downto 23)));
state <= MEM_S;
when STOREI =>
reg_write <= '0';
mem_write <= '1';
mem_read <= '0';
mem_addr <= reg_file(conv_integer
(inst_reg(22 downto 18)))
(22 downto 0);
mem_data <= reg_file(
conv_integer(inst_reg(27 downto 23)));
state <= MEM_S;
when GE =>
reg_write <= '1';
mem_write <= '0';
mem_read <= '0';
reg_num <= inst_reg(27 downto 23);
if(reg_file(conv_integer
(inst_reg(22 downto 18))) >= reg_file(
conv_integer(inst_reg(17 downto 13)))) then
reg_data <= C1_32;
else
reg_data <= C0_32;
end if;
state <= MEM_S;
when EQ =>
reg_write <= '1';
mem_write <= '0';
mem_read <= '0';
reg_num <= inst_reg(27 downto 23);
if(reg_file(conv_integer
(inst_reg(22 downto 18))) = reg_file(
conv_integer(inst_reg(17 downto 13)))) then
reg_data <= C1_32;
else
reg_data <= C0_32;
end if;
state <= MEM_S;
when JNZ =>
reg_write <= '0';
mem_write <= '0';
mem_read <= '0';
if( reg_file(conv_integer(
inst_reg(27 downto 23))) /= C0_23 ) then
pc_reg <= inst_reg(22 downto 0);
end if;
state <= MEM_S;
when ADD =>
reg_write <= '1';
mem_write <= '0';
mem_read <= '0';
reg_num <= inst_reg(27 downto 23);
reg_data1 := reg_file(
conv_integer(inst_reg(22 downto 18)));
reg_data2 := reg_file(
conv_integer(inst_reg(17 downto 13)));
add_result := reg_data1 + reg_data2;
reg_data <= add_result;
--reg_file(
-- conv_integer(inst_reg(22 downto 18)))
-- + reg_file(conv_integer
-- (inst_reg(17 downto 13)));
state <= MEM_S;
when JMP =>
reg_write <= '0';
mem_write <= '0';
mem_read <= '0';
pc_reg <= inst_reg(22 downto 0);
state <= MEM_S;
when NOP =>
reg_write <= '0';
mem_write <= '0';
mem_read <= '0';
state <= MEM_S;
when SHFL =>
reg_write <= '1';
mem_write <= '0';
mem_read <= '0';
reg_num <= inst_reg(27 downto 23);
reg_data <= SHL(reg_file(
conv_integer(inst_reg(27 downto 23))),
inst_reg(22 downto 18));
state <= MEM_S;
when SHFR =>
reg_write <= '1';
mem_write <= '0';
mem_read <= '0';
reg_num <= inst_reg(27 downto 23);
reg_data <= SHR(reg_file(
conv_integer(inst_reg(27 downto 23))),
inst_reg(22 downto 18));
state <= MEM_S;
when others =>
null;
end case;
when MEM_S =>
if(rdy='1' and mem_read = '1') then
data <= Z_32;
addr <= mem_addr;
rd <= '1';
mem_read <= '0';
mem_write <= '0';
state <= MEM_READ1_S;
elsif(rdy='1' and mem_write='1') then
data <= mem_data;
addr <= mem_addr;
wr <= '1';
mem_read <= '0';
mem_write <= '0';
state <= WB_S;
elsif( rdy = '1' ) then
state <= WB_S;
else
state <= MEM_S;
end if;
when MEM_READ1_S =>
state <= MEM_READ2_S;
when MEM_READ2_S =>
if( rdy = '1' ) then
reg_data <= data;
state <= WB_S;
else
state <= MEM_READ2_S;
end if;
when WB_S =>
if( reg_write = '1' ) then
reg_file(conv_integer(reg_num))
<= reg_data;
reg_write <= '0';
end if;
state <= IF_S;
when others =>
state <= IF_S;
end case;
end if;
end process;
end BHV_MIPS;
--**************************************************************************--
configuration CFG_MIPS of MIPS is
for BHV_MIPS
end for;
end CFG_MIPS;
--**************************************************************************--
-- end of file --
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