alu: bessere testbench

[hwmod.git] / src / alu.vhd

diff --git a/src/alu.vhd b/src/alu.vhd
index de0b6a6aa32c4c0d95cce84bfe13a4edfb032a28..2d9e4a7523ea95df162b0c83e6fd07bf4c385385 100644 (file)
--- a/src/alu.vhd
+++ b/src/alu.vhd
@@ -13,7 +13,6 @@ entity alu is
                op2 : in csigned;
                op3 : out csigned;
                do_calc : in std_logic;
-               ack : in std_logic;
                calc_done : out std_logic
        );
 end entity alu;
@@ -34,25 +33,27 @@ begin
        end process;
 
        -- next state
-       process(state, opcode, done_intern)
+       process(state, opcode, done_intern, do_calc)
        begin
                -- set a default value for next state
                state_next <= state;
                -- next state berechnen
                case state is
                        when SIDLE =>
-                               case opcode is
-                                       when ADD =>
-                                               state_next <= SADD;
-                                       when SUB =>
-                                               state_next <= SSUB;
-                                       when MUL =>
-                                               state_next <= SMUL;
-                                       when DIV =>
-                                               state_next <= SDIV;
-                                       when others =>
-                                               state_next <= SIDLE;
-                               end case;
+                               if do_calc = '1' then
+                                       case opcode is
+                                               when ADD =>
+                                                       state_next <= SADD;
+                                               when SUB =>
+                                                       state_next <= SSUB;
+                                               when MUL =>
+                                                       state_next <= SMUL;
+                                               when DIV =>
+                                                       state_next <= SDIV;
+                                               when others =>
+                                                       state_next <= SIDLE;
+                                       end case;
+                               end if;
                        when SADD =>
                                if done_intern = '1' then
                                        state_next <= SDONE;
@@ -70,7 +71,7 @@ begin
                                        state_next <= SDONE;
                                end if;
                        when SDONE =>
-                               if ack = '1' then
+                               if do_calc = '0' then
                                        state_next <= SIDLE;
                                end if;
                end case;
@@ -78,6 +79,8 @@ begin
 
        -- output
        process(state)
+       variable tmperg : csigned;
+       variable multmp : signed(((2*CBITS)-1) downto 0);
        begin
                op3 <= (others => '0');
                calc_done <= '0';
@@ -86,20 +89,23 @@ begin
                        when SIDLE =>
                                done_intern <= '0';
                        when SADD =>
-                               op3 <= op1 + op2;
+                               tmperg := op1 + op2;
                                done_intern <= '1';
                        when SSUB =>
-                               op3 <= op1 - op2;
+                               tmperg := op1 - op2;
                                done_intern <= '1';
                        when SMUL =>
-                               op3 <= op1 * op2;
+                               multmp := op1 * op2;
+                               tmperg(CBITS-1) := multmp((2*CBITS)-1);
+                               tmperg((CBITS-2) downto 0) := multmp((CBITS-2) downto 0);
                                done_intern <= '1';
                        when SDIV =>
-                               op3 <= op1 / op2;
+                               tmperg := op1 / op2;
                                done_intern <= '1';
                        when SDONE =>
                                done_intern <= '1';
                                calc_done <= '1';
+                               op3 <= tmperg;
                end case;
        end process;
 end architecture beh;