Metavalue cleanup for fetch1.vhdl

Signed-off-by: Michael Neuling <mikey@neuling.org>

diff --git a/fetch1.vhdl b/fetch1.vhdl
index af1dd6bda0b0d95b43273f7cb7efd5e3c140ef19..c6d26d7955565b664bbe1c3d10eaf59069972419 100644 (file)
--- a/fetch1.vhdl
+++ b/fetch1.vhdl
@@ -123,15 +123,22 @@ begin
                 raddr := unsigned(r.nia(BTC_ADDR_BITS + 1 downto 2)) +
                          to_unsigned(2, BTC_ADDR_BITS);
                 if advance_nia = '1' then
-                    btc_rd_data <= btc_memory(to_integer(raddr));
-                    btc_rd_valid <= btc_valids(to_integer(raddr));
+                   if is_X(raddr) then
+                       btc_rd_data <= (others => 'X');
+                       btc_rd_valid <= 'X';
+                   else
+                       btc_rd_data <= btc_memory(to_integer(raddr));
+                       btc_rd_valid <= btc_valids(to_integer(raddr));
+                   end if;
                 end if;
                 if btc_wr = '1' then
+                   assert not is_X(btc_wr_addr) report "Writing to unknown address" severity FAILURE;
                     btc_memory(to_integer(unsigned(btc_wr_addr))) <= btc_wr_data;
                 end if;
                 if inval_btc = '1' or rst = '1' then
                     btc_valids <= (others => '0');
                 elsif btc_wr = '1' then
+                   assert not is_X(btc_wr_addr) report "Writing to unknown address" severity FAILURE;
                     btc_valids(to_integer(unsigned(btc_wr_addr))) <= '1';
                 end if;
             end if;