vhdl program of a digital clock & who have ideas to add button pls

two button one to switch and other to increment
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library ieee ;
use ieee.std_logic_1164.all ;
use ieee.std_logic_unsigned.all;
use ieee.numeric_std.all;
use ieee.std_logic_arith.all;
entity horloge is
port (clk1 : in std_logic;
      scan : out std_logic_vector(5 downto 0);
      seg1 : out std_logic_vector(6 downto 0));
end horloge;

--Les entrés sorties interne de l’architecteur --

architecture data_flow of horloge is
signal S1,S2,M1,M2,H1,H2 : std_logic_vector (3 downto 0);
signal tps : std_logic_vector (23 downto 0);
signal s : std_logic_vector(3 downto 0);
signal count : integer range 0 to 5;
signal count1 : integer :=1;
signal clk2   : std_logic :='0';

  --deviseur de frequence (utilisé une fréquence de 1MHz et un conteur 
pour assurer l’affichage contenue sur les afficheurs 7seg) --

begin
process(clk1)
begin
if(clk1'event and clk1='1') then
count1 <=count1+1;
if(count1=500000) then
  clk2<= not clk2;
  count1<= 1;
end if ;
 count <=count+1;
  if (count=5) then
   count<=0;
end if ;
case count is
when 0 => S <= tps (3 downto 0) ;
   scan<="100000";
when 1 => S <= tps (7 downto 4) ;
   scan<="010000";
when 2 => S <= tps (11 downto 8) ;
   scan<="001000";
when 3 => S <= tps (15 downto 12) ;
   scan<="000100";
when 4 => S <= tps (19 downto 16) ;
   scan<="000010";
when 5 => S <= tps (23 downto 20) ;
   scan<="000001";
end case;
end if;
end process;

-- lincrementation (ce code on a incrémenté les secondes, Les minutes et 
les heures) --

process (clk2)
begin
if clk2'event and clk2= '1' then
      S1<=S1+1;
     if S1>"1000" then
           s2<=S2+1;
           S1<="0000";
      if S2>"0100" then
           s1<="0000";
           S2<="0000";
           M1<=M1+1;
      if M1>"1000" then
           M2<= M2+1;
           M1<="0000";
      if M2>"0100" then
           H1<= H1+1;
           M1<="0000";
           M2<="0000";
      if H1>"1000" then
           H2<= H2+1;
           M1<="0000";
       if H2>"0100" then
           H1<="0000";
           H2<="0000";
end if ;
end if ;
end if ;
end if ;
end if ;
end if ;
  tps<= S1&S2&M1&M2&H1&H2;
end if ;
end process;

-- l'afficheur 7seg --
seg1<= "1111110" when S="0000" else
       "0110000" when S="0001" else
       "1101101" when S="0010" else
       "1111001" when S="0011" else
       "0110011" when S="0100" else
       "1011011" when S="0101" else
       "1011111" when S="0110" else
       "1110000" when S="0111" else
       "1111111" when S="1000" else
       "1111011" when S="1001" else
       "1111110";
end data_flow;