library work;
use work.common.all;
+use work.crhelpers.all;
entity writeback is
- port (
- clk : in std_ulogic;
+ port (
+ clk : in std_ulogic;
- e_in : in Execute2ToWritebackType;
- l_in : in Loadstore2ToWritebackType;
- m_in : in MultiplyToWritebackType;
+ e_in : in Execute1ToWritebackType;
+ l_in : in Loadstore1ToWritebackType;
+ fp_in : in FPUToWritebackType;
- w_out : out WritebackToRegisterFileType;
- c_out : out WritebackToCrFileType;
+ w_out : out WritebackToRegisterFileType;
+ c_out : out WritebackToCrFileType;
- complete_out : out std_ulogic
- );
+ complete_out : out instr_tag_t
+ );
end entity writeback;
architecture behaviour of writeback is
- type reg_internal_type is record
- complete : std_ulogic;
- end record;
- type reg_type is record
- w : WritebackToRegisterFileType;
- c : WritebackToCrFileType;
- end record;
- signal r, rin : reg_type;
- signal r_int, rin_int : reg_internal_type;
begin
- writeback_0: process(clk)
- begin
- if rising_edge(clk) then
- r <= rin;
- r_int <= rin_int;
- end if;
- end process;
-
- writeback_1: process(all)
- variable x: std_ulogic_vector(0 downto 0);
- variable y: std_ulogic_vector(0 downto 0);
- variable z: std_ulogic_vector(0 downto 0);
- variable v : reg_type;
- variable v_int : reg_internal_type;
- begin
- v := r;
- v_int := r_int;
-
- x := "" & e_in.valid;
- y := "" & l_in.valid;
- z := "" & m_in.valid;
- assert (to_integer(unsigned(x)) + to_integer(unsigned(y)) + to_integer(unsigned(z))) <= 1;
-
- x := "" & e_in.write_enable;
- y := "" & l_in.write_enable;
- z := "" & m_in.write_reg_enable;
- assert (to_integer(unsigned(x)) + to_integer(unsigned(y)) + to_integer(unsigned(z))) <= 1;
-
- assert not(e_in.write_cr_enable = '1' and m_in.write_cr_enable = '1');
-
- v.w := WritebackToRegisterFileInit;
- v.c := WritebackToCrFileInit;
-
- v_int.complete := '0';
- if e_in.valid = '1' or l_in.valid = '1' or m_in.valid = '1' then
- v_int.complete := '1';
- end if;
-
- if e_in.write_enable = '1' then
- v.w.write_reg := e_in.write_reg;
- v.w.write_data := e_in.write_data;
- v.w.write_enable := '1';
- end if;
-
- if e_in.write_cr_enable = '1' then
- v.c.write_cr_enable := '1';
- v.c.write_cr_mask := e_in.write_cr_mask;
- v.c.write_cr_data := e_in.write_cr_data;
- end if;
-
- if l_in.write_enable = '1' then
- v.w.write_reg := l_in.write_reg;
- v.w.write_data := l_in.write_data;
- v.w.write_enable := '1';
- end if;
-
- if m_in.write_reg_enable = '1' then
- v.w.write_enable := '1';
- v.w.write_reg := m_in.write_reg_nr;
- v.w.write_data := m_in.write_reg_data;
- end if;
-
- if m_in.write_cr_enable = '1' then
- v.c.write_cr_enable := '1';
- v.c.write_cr_mask := m_in.write_cr_mask;
- v.c.write_cr_data := m_in.write_cr_data;
- end if;
-
- -- Update registers
- rin <= v;
- rin_int <= v_int;
-
- -- Update outputs
- complete_out <= r_int.complete;
- w_out <= r.w;
- c_out <= r.c;
- end process;
+ writeback_0: process(clk)
+ variable x : std_ulogic_vector(0 downto 0);
+ variable y : std_ulogic_vector(0 downto 0);
+ variable w : std_ulogic_vector(0 downto 0);
+ begin
+ if rising_edge(clk) then
+ -- Do consistency checks only on the clock edge
+ x(0) := e_in.valid;
+ y(0) := l_in.valid;
+ w(0) := fp_in.valid;
+ assert (to_integer(unsigned(x)) + to_integer(unsigned(y)) +
+ to_integer(unsigned(w))) <= 1 severity failure;
+
+ x(0) := e_in.write_enable or e_in.exc_write_enable;
+ y(0) := l_in.write_enable;
+ w(0) := fp_in.write_enable;
+ assert (to_integer(unsigned(x)) + to_integer(unsigned(y)) +
+ to_integer(unsigned(w))) <= 1 severity failure;
+
+ w(0) := e_in.write_cr_enable;
+ x(0) := (e_in.write_enable and e_in.rc);
+ y(0) := fp_in.write_cr_enable;
+ assert (to_integer(unsigned(w)) + to_integer(unsigned(x)) +
+ to_integer(unsigned(y))) <= 1 severity failure;
+
+ assert not (e_in.valid = '1' and e_in.instr_tag.valid = '0') severity failure;
+ assert not (l_in.valid = '1' and l_in.instr_tag.valid = '0') severity failure;
+ assert not (fp_in.valid = '1' and fp_in.instr_tag.valid = '0') severity failure;
+ end if;
+ end process;
+
+ writeback_1: process(all)
+ variable cf: std_ulogic_vector(3 downto 0);
+ variable zero : std_ulogic;
+ variable sign : std_ulogic;
+ variable scf : std_ulogic_vector(3 downto 0);
+ begin
+ w_out <= WritebackToRegisterFileInit;
+ c_out <= WritebackToCrFileInit;
+
+ complete_out <= instr_tag_init;
+ if e_in.valid = '1' then
+ complete_out <= e_in.instr_tag;
+ elsif l_in.valid = '1' then
+ complete_out <= l_in.instr_tag;
+ elsif fp_in.valid = '1' then
+ complete_out <= fp_in.instr_tag;
+ end if;
+
+ if e_in.exc_write_enable = '1' then
+ w_out.write_reg <= e_in.exc_write_reg;
+ w_out.write_data <= e_in.exc_write_data;
+ w_out.write_enable <= '1';
+ else
+ if e_in.write_enable = '1' then
+ w_out.write_reg <= e_in.write_reg;
+ w_out.write_data <= e_in.write_data;
+ w_out.write_enable <= '1';
+ end if;
+
+ if e_in.write_cr_enable = '1' then
+ c_out.write_cr_enable <= '1';
+ c_out.write_cr_mask <= e_in.write_cr_mask;
+ c_out.write_cr_data <= e_in.write_cr_data;
+ end if;
+
+ if e_in.write_xerc_enable = '1' then
+ c_out.write_xerc_enable <= '1';
+ c_out.write_xerc_data <= e_in.xerc;
+ end if;
+
+ if fp_in.write_enable = '1' then
+ w_out.write_reg <= fp_in.write_reg;
+ w_out.write_data <= fp_in.write_data;
+ w_out.write_enable <= '1';
+ end if;
+
+ if fp_in.write_cr_enable = '1' then
+ c_out.write_cr_enable <= '1';
+ c_out.write_cr_mask <= fp_in.write_cr_mask;
+ c_out.write_cr_data <= fp_in.write_cr_data;
+ end if;
+
+ if l_in.write_enable = '1' then
+ w_out.write_reg <= l_in.write_reg;
+ w_out.write_data <= l_in.write_data;
+ w_out.write_enable <= '1';
+ end if;
+
+ if l_in.rc = '1' then
+ -- st*cx. instructions
+ scf(3) := '0';
+ scf(2) := '0';
+ scf(1) := l_in.store_done;
+ scf(0) := l_in.xerc.so;
+ c_out.write_cr_enable <= '1';
+ c_out.write_cr_mask <= num_to_fxm(0);
+ c_out.write_cr_data(31 downto 28) <= scf;
+ end if;
+
+ -- Perform CR0 update for RC forms
+ -- Note that loads never have a form with an RC bit, therefore this can test e_in.write_data
+ if e_in.rc = '1' and e_in.write_enable = '1' then
+ zero := not (or e_in.write_data(31 downto 0));
+ if e_in.mode_32bit = '0' then
+ sign := e_in.write_data(63);
+ zero := zero and not (or e_in.write_data(63 downto 32));
+ else
+ sign := e_in.write_data(31);
+ end if;
+ c_out.write_cr_enable <= '1';
+ c_out.write_cr_mask <= num_to_fxm(0);
+ cf(3) := sign;
+ cf(2) := not sign and not zero;
+ cf(1) := zero;
+ cf(0) := e_in.xerc.so;
+ c_out.write_cr_data(31 downto 28) <= cf;
+ end if;
+ end if;
+ end process;
end;
projects / microwatt.git / blobdiff