could you add swap command to this code? (FFO MEMORY N VHDL)

library IEEE; use IEEE.std_logic_1164.all; use IEEE.std_logic_unsigned.all; entity FIFO_LOGIC is generic (N: integer := 3); port (CLK, PUSH, POP, INIT: in std_logic; ADD: out std_logic_vector(N-1 downto 0); FULL, EMPTY, WE, NOPUSH, NOPOP: buffer std_logic); end entity FIFO_LOGIC; architecture RTL of FIFO_LOGIC is signal WPTR, RPTR: std_logic_vector(N-1 downto 0); signal LASTOP: std_logic; begin SYNC: process (CLK) begin if (CLK'event and CLK = '1') then if (INIT = '1') then -- initialization -- WPTR <= (others => '0'); RPTR <= (others => '0'); LASTOP <= '0'; elsif (POP = '1' and EMPTY = '0') then -- pop -- RPTR <= RPTR + 1; LASTOP <= '0'; elsif (PUSH = '1' and FULL = '0') then -- push -- WPTR <= WPTR + 1; LASTOP <= '1'; end if; -- otherwise all Fs hold their value -- end if; end process SYNC; COMB: process (PUSH, POP, WPTR, RPTR, LASTOP, FULL, EMPTY) begin -- full and empty flags -- if (RPTR = WPTR) then if (LASTOP = '1') then FULL <= '1'; EMPTY <= '0'; else FULL <= '0'; EMPTY <= '1'; end if; else FULL <= '0'; EMPTY <= '0'; end if; SEQUENTIAL LOGIC MODELING EXAMPLE USING 2-PROCESS MODELING STYLE C. E. Stroud, ECE Dept., Auburn Univ. 3 8/06 -- address, write enable and nopush/nopop logic -- if (POP = '0' and PUSH = '0') then -- no operation -- ADD <= RPTR; WE <= '0'; NOPUSH <= '0'; NOPOP <= '0'; elsif (POP = '0' and PUSH = '1') then -- push only -- ADD <= WPTR; NOPOP <= '0'; if (FULL = '0') then -- valid write condition -- WE <= '1'; NOPUSH <= '0'; else -- no write condition -- WE <= '0'; NOPUSH <= '1'; end if; elsif (POP = '1' and PUSH = '0') then -- pop only -- ADD <= RPTR; NOPUSH <= '0'; WE <= '0'; if (EMPTY = '0') then -- valid read condition -- NOPOP <= '0'; else NOPOP <= '1'; -- no red condition -- end if; else -- push and pop at same time if (EMPTY = 0) then -- valid pop -- ADD <= RPTR; WE <= '0'; NOPUSH <= '1'; NOPOP <= '0'; else ADD <= wptr; WE <= 1; NOPUSH <= 0; NOPOP <= 1; end if; end if; end process COMB; end architecture RTL;