From 1871adac6dfe53049f8ecebe100419db79e2600e Mon Sep 17 00:00:00 2001
From: Greek <e1128193@student.tuwien.ac.at>
Date: Tue, 7 Dec 2021 11:16:47 +0100
Subject: [PATCH] Add a Verbatim Key Hash Generator

Add a Key Hash Generator that just generates a Key Hash with the
verbatim contents of the Type Key Fields.
This is the case for all Types with a combined Key Field size less than
16 Bytes.
---
 src/verbatim_key_hash_generator.vhd | 80 +++++++++++++++++++++++++++++
 1 file changed, 80 insertions(+)
 create mode 100644 src/verbatim_key_hash_generator.vhd

diff --git a/src/verbatim_key_hash_generator.vhd b/src/verbatim_key_hash_generator.vhd
new file mode 100644
index 0000000..9d22550
--- /dev/null
+++ b/src/verbatim_key_hash_generator.vhd
@@ -0,0 +1,80 @@
+library ieee;
+use ieee.std_logic_1164.all;
+use ieee.numeric_std.all;
+
+use work.rtps_package.all;
+use work.rtps_config_package.all;
+
+architecture arch of key_hash_generator is
+    
+    constant MAX_CNT_BOUND : natural := (KEY_HASH_WIDTH/data_in'length);
+    
+    type STAGE_TYPE is (IDLE, GEN_KEY_HASH, FINALIZE);
+    
+    signal stage, stage_next : STAGE_TYPE;
+    signal cnt, cnt_next : natural range 0 to MAX_CNT_BOUND-1;
+    signal kh, kh_next : std_logic_vector(KEY_HASH_WIDTH-1 downto 0);
+    
+begin
+    key_hash    <= kh;
+    
+    kh_prc : process(all)
+    begin
+        -- DEFAULT
+        stage_next      <= stage;
+        kh_next         <= kh;
+        cnt_next        <= cnt;
+        -- DEFAULT Unregistered
+        ack         <= '0';
+        ready_in    <= '0';
+        done        <= '0';
+        
+        case (stage) is
+            when IDLE =>
+                if (start = '1') then
+                    ack         <= '1';
+                    stage_next  <= GEN_KEY_HASH;
+                    -- Reset
+                    kh_next     <= (others => '0');
+                    cnt_next    <= 0;
+                end if;
+            when GEN_KEY_HASH =>
+                ready_in    <= '1';
+                -- Input Guard
+                if (valid_in = '1') then
+                    kh_next <= write_sub_vector(kh, data_in, cnt, TRUE);
+                    
+                    -- Last Word
+                    if (last_word_in = '1') then
+                        stage_next  <= FINALIZE;
+                    elsif (cnt = MAX_CNT_BOUND-1) then
+                        -- Reset (Prevent overflow)
+                        cnt_next    <= 0;
+                    else
+                        cnt_next    <= cnt + 1;
+                    end if;
+                end if;
+            when FINALIZE =>
+                done        <= '1';
+                stage_next  <= IDLE;
+            when others =>
+                null;
+        end case;
+    end process;
+    
+    sync_prc : process(clk)
+    begin
+        if rising_edge(clk) then
+            if (reset = '1') then
+                stage       <= IDLE;
+                cnt         <= 0;
+                kh          <= (others => '0');
+            else
+                stage       <= stage_next;
+                cnt         <= cnt_next;
+                kh          <= kh_next;
+            end if;
+        end if;
+    end process;
+    
+end architecture;
\ No newline at end of file