library ieee;use ieee.std_logic_1164.all;use ieee.numeric_std.all;use work.Constants.all; entity Analyser is    port (reset, clk : in  std_logic;       analyse : in std_logic;		 store : in std_logic;		 		 debounced: out std_logic;           keychanged : out std_logic;       released : out std_logic;              sample_col : in col;       sample_row_number : in row_number;              conv_col : out col_number;       conv_row : out row_number              );    end Analyser;architecture Analyser_arc of Analyser is   function ones_in_column(inp: col) return col_number isvariable number : col_number;begin    number := 0;    for i in inp'range loop       if inp(i)='1' then number := number+1;       end if;    end loop;    return number;end ones_in_column;function ones_in_row(inp: row) return row_number isvariable number : row_number;begin    number := 0;    for i in inp'range loop       if inp(i)='1' then number := number + 1;       end if;    end loop;    return number;end ones_in_row;function priority_encode(inp: col) return col_number isvariable tmp: col_number;begin    if inp(5)='1' then tmp:= 5;    elsif inp(4)='1' then tmp:= 4;    elsif inp(3)='1' then tmp:= 3;    elsif inp(2)='1' then tmp:= 2;    elsif inp(1)='1' then tmp:= 1;    else tmp:= 0;    end if;    return tmp;end priority_encode;--reduce or function to look for key press in a columnfunction key_pressed(inp : row) return std_logic is   variable tmp: std_logic;begin    tmp:='0';    for i in inp'range loop       tmp := tmp or inp(i);    end loop;    return tmp;end key_pressed;--function that checks whether the new key specified by col_number and row_number is valid--large input is necessary to make it a legal functionfunction valid_key(colnum: col_number; rownum: row_number; row0:row; row1:row; row2:row; row3:row; row4:row; row5:row; keysdown: key_number) return std_logic isvariable colpress : col;variable rowpress : row;variable valid :std_logic;  begin    valid := '1'; --valid until proven otherwise    colpress := "000000";    rowpress := "000000000000";        colpress(0):= key_pressed(row0);    colpress(1):= key_pressed(row1);    colpress(2):= key_pressed(row2);    colpress(3):= key_pressed(row3);    colpress(4):= key_pressed(row4);    colpress(5):= key_pressed(row5);        for i in number_of_cols-1 downto 0 loop    	rowpress(i) := row0(i) or row1(i)  or row2(i)  or row3(i)  or row4(i)  or row5(i);    end loop;        --add virtual key        colpress(colnum) := '1';    rowpress(rownum) := '1';              if (keysdown >= max_keys_pressed) then  --too many keys pressed       valid := '0';    elsif (keysdown = 2) then --check for ghosting       if (ones_in_column(colpress)=2 and ones_in_row(rowpress)=2) then           valid := '0';       end if;    end if;           return valid;end valid_key;signal debounce_state : col;signal keysdown : natural range 0 to max_keys_pressed ;signal next_keysdown : natural range 0 to max_keys_pressed;signal keychange : std_logic;signal release : std_logic;signal conv_col_number : col_number;signal conv_row_number : row_number;signal previous_sample : col; --last sampled columnsignal row0 : row;signal row1 : row;	signal row2 : row;signal row3 : row;signal row4 : row;signal row5 : row;begin    			--look for valid keychange	detector: process ( conv_col_number, conv_row_number, keysdown, row0, row1, row2, row3, row4, row5, sample_row_number, previous_sample)	variable colpress : col_number;		begin	colpress := 0;	if ((row0(sample_row_number) xor previous_sample(0))='1') then	--change detected	--keychange if valid or !pressed_down			keychange <= (not previous_sample(0)) or valid_key(0, sample_row_number, row0, row1, row2, row3, row4, row5, keysdown);			release <= not previous_sample(0);		 			colpress := 0;	elsif((row1(sample_row_number) xor previous_sample(1))='1') then			keychange <= (not previous_sample(1)) or valid_key(1, sample_row_number, row0, row1, row2, row3, row4, row5, keysdown);			release <= not previous_sample(1);		 			colpress := 1;	elsif((row2(sample_row_number) xor previous_sample(2))='1') then			keychange <= (not previous_sample(2)) or valid_key(2, sample_row_number, row0, row1, row2, row3, row4, row5, keysdown);			release <= not previous_sample(2);		 			colpress := 2;	elsif((row3(sample_row_number) xor previous_sample(3))='1') then			keychange <= (not previous_sample(3)) or valid_key(3, sample_row_number, row0, row1, row2, row3, row4, row5, keysdown);			release <= not previous_sample(3);		 			colpress := 3;	elsif((row4(sample_row_number) xor previous_sample(4))='1') then			keychange <= (not previous_sample(4)) or valid_key(4, sample_row_number, row0, row1, row2, row3, row4, row5, keysdown);			release <= not previous_sample(4);		 			colpress := 4;	elsif ((row5(sample_row_number) xor previous_sample(5))='1') then			keychange <= (not previous_sample(5)) or valid_key(5, sample_row_number, row0, row1, row2, row3, row4, row5, keysdown);			release <= not previous_sample(5);		 			colpress := 5;	else			keychange <= '0';			release <= '0';	end if;		conv_col_number <= colpress;	conv_row_number <= sample_row_number;	end process;	next_keysdown <= keysdown+1 when keychange='1' and release='0'							else						  keysdown-1 when keychange='1' and release='1'						  	else						  keysdown;						  	storer:process 	begin	wait until rising_edge(clk);	if (reset='1') then	   row0 <= "000000000000";		row1 <= "000000000000";		row2 <= "000000000000";		row3 <= "000000000000";		row4 <= "000000000000";		row5 <= "000000000000";		keychanged <= '0';		released <= '0';		keysdown <= 0;		conv_col <= 0;		conv_row <= 0; 	elsif (store='1') then  		 	if (debounce_state = "000000") then       		 	keychanged <= keychange;				   released <= release;				   keysdown <= next_keysdown;			      conv_col <= conv_col_number;	     	         conv_row <= conv_row_number;				   if (keychange='1') then 								case conv_col_number is							when 0 => row0(conv_row_number) <= previous_sample(0);							when 1 => row1(conv_row_number) <= previous_sample(1);							when 2 => row2(conv_row_number) <= previous_sample(2);							when 3 => row3(conv_row_number) <= previous_sample(3);							when 4 => row4(conv_row_number) <= previous_sample(4);							when 5 => row5(conv_row_number) <= previous_sample(5);							when others => null;						end case; 	 				   end if;			else			   keychanged <= '0';           	released <= '0';  		   end if;	else	  keychanged <= '0';	  released <= '0';	end if;	end process;	--debouncing	debouncer: process	variable counter : natural range 0 to debounce_count;	begin	wait until rising_edge(clk);		if (reset = '1') then	   debounce_state <= (others=> '0');	   previous_sample <= (others => '0');		counter := debounce_count;		debounced <= '0';	else		if (analyse='1') then	 		if (counter > 0 and counter < debounce_count) then            counter := counter - 1;	 	      debounce_state <= debounce_state or (previous_sample xor sample_col);	 	      debounced <= '0';	 	   end if;	 	   	 	 	if (counter = debounce_count) then	 		   previous_sample <= sample_col; 	 		   counter := counter -1 ;	 		end if;	 			 		if (counter = 0) then	 		   debounced <= '1';			end if; 			  		else 		   counter := debounce_count;		   debounced <= '0';		   debounce_state <= (others=> '0');		end if;		 	end if;	end process;	end Analyser_arc;