+constant EXTWORDL : integer := log2c(4);
+constant BYTEADDR : integer := log2c(4);
+constant PCOUNT : integer := log2c(4);
+constant EXTWORDS : integer := EXTWORDL + BYTEADDR;
+
+subtype ext_addrid_t is std_logic_vector(gp_register_t'high - EXTWORDS downto 0);
+subtype ext_addr_t is std_logic_vector((gp_register_t'high-BYTEADDR) downto 0);
+subtype pointer_count is std_logic_vector(PCOUNT-1 downto 0);
+