history/display: backspace logic

[hwmod.git] / src / display.vhd

diff --git a/src/display.vhd b/src/display.vhd
index ed8cac9a8e755afa053b2438b4a9e77982778b28..8b0a9cc1748b0e257f24cb6ef1b36141304a01e3 100644 (file)
--- a/src/display.vhd
+++ b/src/display.vhd
@@ -13,6 +13,7 @@ entity display is
                -- History
                d_new_eingabe : in std_logic;
                d_new_result : in std_logic;
+               d_new_bs : in std_logic;
                d_zeile : out hzeile;
                d_spalte : out hspalte;
                d_get : out std_logic;
@@ -26,8 +27,9 @@ entity display is
 end entity display;
 
 architecture beh of display is
-       type DISPLAY_STATE is (SIDLE, S_NEW_RESULT, S_NEW_INPUT, S_COUNTUP, S_GETCH,
-       S_CR1, S_NL1, S_PUTCH1, S_PUTCH2, S_WAIT, S_NOP1);
+       type DISPLAY_STATE is (SIDLE, S_NEW_BS, S_BACK, S_BLANK, S_NEW_RESULT,
+               S_NEW_INPUT, S_COUNTUP, S_GETCH, S_CR1, S_NL1, S_PUTCH1, S_PUTCH2,
+               S_WAIT, S_NOP1);
        signal state_int, state_next : DISPLAY_STATE;
        signal d_zeile_int, d_zeile_next : hzeile;
        signal d_spalte_int, d_spalte_next : hspalte;
@@ -68,8 +70,8 @@ begin
        end process;
 
        -- next state
-       process(state_int, d_new_result, d_new_eingabe, d_done, free, d_spalte_int,
-               d_char, istate_int)
+       process(state_int, d_new_result, d_new_eingabe, d_new_bs, d_done, free,
+               d_spalte_int, d_char, istate_int)
        begin
                state_next <= state_int;
                istate_next <= istate_int;
@@ -77,16 +79,36 @@ begin
                case state_int is
                        when SIDLE =>
                                istate_next <= b"111"; -- default: immer wieder ins SIDLE;
-                               if d_new_eingabe = '1' then
+                               if d_new_bs = '1' then
+                                       state_next <= S_NEW_BS;
+                               elsif d_new_eingabe = '1' then
                                        state_next <= S_NEW_INPUT;
                                end if;
                                if d_new_result = '1' then
                                        state_next <= S_NEW_RESULT;
                                end if;
+
                        when S_NEW_RESULT =>
                                state_next <= S_CR1;
                        when S_NEW_INPUT =>
                                state_next <= S_COUNTUP;
+
+                       when S_NEW_BS =>
+                               state_next <= S_BACK;
+                       when S_BACK =>
+                               if free = '0' then
+                                       state_next <= S_WAIT;
+                                       case istate_int is
+                                               when b"111" => istate_next <= b"001"; -- => danach S_BLANK und wieder hierher
+                                               when others => istate_next <= b"111"; -- => danach SIDLE
+                                       end case;
+                               end if;
+                       when S_BLANK =>
+                               if free = '0' then
+                                       state_next <= S_WAIT;
+                                       istate_next <= b"010"; -- => danach S_BACK
+                               end if;
+
                        when S_CR1 =>
                                if free = '0' then
                                        state_next <= S_WAIT;
@@ -97,6 +119,7 @@ begin
                                        state_next <= S_WAIT;
                                        istate_next <= b"111"; -- => wieder nach SIDLE
                                end if;
+
                        when S_COUNTUP =>
                                state_next <= S_GETCH;
                        when S_GETCH =>
@@ -117,6 +140,8 @@ begin
                                if free = '1' then
                                        case istate_int is
                                                when b"000" => state_next <= S_NL1;
+                                               when b"001" => state_next <= S_BLANK;
+                                               when b"010" => state_next <= S_BACK;
                                                when others => state_next <= SIDLE;
                                        end case;
                                end if;
@@ -136,20 +161,33 @@ begin
                case state_int is
                        when SIDLE =>
                                null;
-                       when S_NEW_INPUT =>
-                               null;
                        when S_NEW_RESULT =>
                                d_spalte_next <= (others => '0');
                                case d_zeile_int is
                                        when "11111" => d_zeile_next <= "00000";
                                        when others => d_zeile_next <= std_logic_vector(unsigned(d_zeile_int) + 1);
                                end case;
+                       when S_NEW_INPUT =>
+                               null;
+
+                       when S_NEW_BS =>
+                               -- underflow check schon im history modul
+                               d_spalte_next <= std_logic_vector(unsigned(d_spalte_int) - 1);
+                       when S_BACK =>
+                               -- einen schritt zurueck
+                               command_next <= COMMAND_SET_CURSOR_COLUMN;
+                               command_data_next <= x"ffffff" & '0' & std_logic_vector(unsigned(d_spalte_int));
+                       when S_BLANK =>
+                               command_next <= COMMAND_SET_CHAR;
+                               command_data_next <= x"ffffff" & x"20"; -- white space
+
                        when S_CR1 =>
                                command_next <= COMMAND_SET_CHAR;
                                command_data_next <= x"ffffff" & x"0d"; -- carrige return
                        when S_NL1 =>
                                command_next <= COMMAND_SET_CHAR;
                                command_data_next <= x"ffffff" & x"0a"; -- newline
+
                        when S_COUNTUP =>
                                d_get_next <= '1';
                                d_spalte_next <= std_logic_vector(unsigned(d_spalte_int) + 1);