From 1e84f090b7b379416a8ca0d9b7d925e85f28bcf2 Mon Sep 17 00:00:00 2001
From: Davide <davidecavagnola@gmail.com>
Date: Wed, 9 Apr 2025 12:52:28 +0200
Subject: [PATCH] Implement state machine in depacketizer for packet processing
 and add top auto-set option in project configuration

---
 LAB2/src/depacketizer.vhd | 67 ++++++++++++++++++++++++++++++++++++++-
 LAB2/vivado/lab2/lab2.xpr |  1 +
 2 files changed, 67 insertions(+), 1 deletion(-)

diff --git a/LAB2/src/depacketizer.vhd b/LAB2/src/depacketizer.vhd
index 7f979bd..8544297 100644
--- a/LAB2/src/depacketizer.vhd
+++ b/LAB2/src/depacketizer.vhd
@@ -26,10 +26,75 @@ end entity depacketizer;
 
 architecture rtl of depacketizer is
 
-   
+    -- Enumeration for the state machine
+    -- IDLE: Waiting for the start of a new packet
+    -- STREAMING: Actively processing and forwarding packet data
+    type state_type is (IDLE, STREAMING);
+    signal state : state_type := IDLE;
 
+    -- Buffer to handle backpressure
+    signal buffer_in : std_logic_vector(7 downto 0) := (others => '0');
+    signal buffer_valid  : std_logic := '0'; -- Indicates if buffer_in contains valid data
 begin
 
+    depacketizer_fsm: process(clk)
+    begin
+        if rising_edge(clk) then
+            if aresetn = '0' then
+                -- Reset: back to idle and clear everything
+                state         <= IDLE;
+                s_axis_tready <= '0';
+                m_axis_tvalid <= '0';
+                m_axis_tlast  <= '0';
+                m_axis_tdata  <= (others => '0');
+                buffer_in    <= (others => '0');
+                buffer_valid  <= '0';
 
+            else
+                -- Defaults for each clock cycle
+                s_axis_tready <= '1';
+                m_axis_tvalid <= '0';
+                m_axis_tlast  <= '0';
+
+                case state is
+
+                    when IDLE =>
+                        -- Wait for start of a new packet
+                        if s_axis_tvalid = '1' then
+                            if s_axis_tdata = std_logic_vector(to_unsigned(HEADER, 8)) then
+                                state <= STREAMING;
+                            end if;
+                        end if;
+
+                    when STREAMING =>
+                        if s_axis_tvalid = '1' then
+                            -- End of packet detected
+                            if s_axis_tdata = std_logic_vector(to_unsigned(FOOTER, 8)) then
+                                state        <= IDLE;
+                                m_axis_tlast <= '1';  -- Let receiver know packet ends
+                            else
+                                -- Valid payload: send to output
+                                if buffer_valid = '1' then
+                                    if m_axis_tready = '1' then
+                                        m_axis_tdata  <= buffer_in;
+                                        m_axis_tvalid <= '1';
+                                        buffer_valid  <= '0'; -- Clear the buffer
+                                    end if;
+                                else
+                                    if m_axis_tready = '1' then
+                                        m_axis_tdata  <= s_axis_tdata;
+                                        m_axis_tvalid <= '1';
+                                    else
+                                        buffer_in    <= s_axis_tdata;
+                                        buffer_valid  <= '1'; -- Mark buffer as valid
+                                    end if;
+                                end if;
+                            end if;
+                        end if;
+
+                end case;
+            end if;
+        end if;
+    end process;
 
 end architecture;
diff --git a/LAB2/vivado/lab2/lab2.xpr b/LAB2/vivado/lab2/lab2.xpr
index 6f047fd..5017af4 100644
--- a/LAB2/vivado/lab2/lab2.xpr
+++ b/LAB2/vivado/lab2/lab2.xpr
@@ -136,6 +136,7 @@
       <Config>
         <Option Name="DesignMode" Val="RTL"/>
         <Option Name="TopModule" Val="lab_2_wrapper"/>
+        <Option Name="TopAutoSet" Val="TRUE"/>
       </Config>
     </FileSet>
     <FileSet Name="constrs_1" Type="Constrs" RelSrcDir="$PSRCDIR/constrs_1" RelGenDir="$PGENDIR/constrs_1">