mac: Add tx_active output

trashernet/trashernet_mac.vhd

@@ -215,6 +215,8 @@ begin
 		phy_in.tx_data_en <= '1' when tx_state /= IDLE else '0';
 		crc_clear         <= '1' when tx_state = HEADER else '0';
 		phy_in.tx_data    <= sr(sr'low);
+
+		mac_out.tx_active <= phy_out.tx_active;
 	end block tx;
 
 end architecture rtl;

trashernet/trashernet_pkg.vhd

@@ -59,6 +59,7 @@ package trashernet_pkg is
 		rx_mac_data       : byte;       -- Ethernet data (after Ethertype)
 		rx_mac_valid      : std_logic;  -- `rx_mac` values (headers + data) are valid
 		tx_mac_data_ack   : std_logic;  -- The byte on `tx_mac_data` has been latched. Update to next word.
+		tx_active         : std_logic;  -- Transmission in progress
 
 		rx_mac_crc_ok     : std_logic;  -- End of packet, CRC OK (strobe independent from other rx_mac fields)
 		rx_mac_crc_error  : std_logic;  -- End of packet, CRC invalid