Subversion Repositories z80soc

library IEEE;

use IEEE.std_logic_1164.all;

use IEEE.std_logic_unsigned.all;

use IEEE.numeric_std.all;

ENTITY video is

        PORT(   CLOCK_25                : IN STD_LOGIC;

                        VRAM_DATA               : IN STD_LOGIC_VECTOR(7 DOWNTO 0);

                        VRAM_ADDR               : OUT STD_LOGIC_VECTOR(12 DOWNTO 0);

                        VRAM_CLOCK              : OUT STD_LOGIC;

                        VRAM_WREN               : OUT STD_LOGIC;

                        VGA_R,

                        VGA_G,

                        VGA_B                   : OUT STD_LOGIC;

                        VGA_HS,

                        VGA_VS                  : OUT STD_LOGIC);

END video;

ARCHITECTURE A OF video IS

        -- Added for VDU support

        constant vid_width              : std_logic_vector := "001010000"; -- 80 columns

        signal Clock_video              : std_logic;

        signal VGA_R_sig                : std_logic;

        signal VGA_G_sig                : std_logic;

        signal VGA_B_sig                : std_logic;

        signal pixel_row_sig    : std_logic_vector(9 downto 0);

        signal pixel_column_sig : std_logic_vector(9 downto 0);

        signal pixel_clock_sig  : std_logic;

        signal char_addr_sig    : std_logic_vector(7 downto 0);

        signal font_row_sig             : std_logic_vector(2 downto 0);

        signal font_col_sig             : std_logic_vector(2 downto 0);

        signal pixel_sig                : std_logic;

        signal video_on_sig             : std_logic;

COMPONENT VGA_SYNC

        PORT(   clock_25Mhz                                                     : IN    STD_LOGIC;

                        red, green, blue                                        : IN    STD_LOGIC;

                        red_out, green_out, blue_out            : OUT   STD_LOGIC;

                        horiz_sync_out, vert_sync_out,

                        video_on, pixel_clock                           : OUT   STD_LOGIC;

                        pixel_row, pixel_column                         : OUT   STD_LOGIC_VECTOR(9 DOWNTO 0));

END COMPONENT;

COMPONENT charrom

        port (

                        clk                                     : IN    STD_LOGIC;

                        character_address                       : IN    STD_LOGIC_VECTOR(7 DOWNTO 0);

                        font_row, font_col              : IN    STD_LOGIC_VECTOR(2 DOWNTO 0);

                        rom_mux_output                  : OUT   STD_LOGIC);

END COMPONENT;

BEGIN

        VGA_R_sig <= '0';

        VGA_G_sig <= '0';

        VGA_B_sig <= pixel_sig;

        -- Fonts ROM read

        VRAM_WREN <= '1'; -- port b is always set for read (High)

        VRAM_CLOCK <= pixel_clock_sig;

        VRAM_ADDR <= (pixel_row_sig(9 downto 4) * "0101000" + pixel_column_sig(9 downto 4));

        -- Fonts ROM read

        char_addr_sig <= VRAM_DATA;

        font_row_sig(2 downto 0) <= pixel_row_sig(3 downto 1);

        font_col_sig(2 downto 0) <= pixel_column_sig(3 downto 1);

        vga_sync_inst : vga_sync

                port map (

                        clock_25Mhz                     => CLOCK_25,

                        red                                     => VGA_R_sig,

                        green                                   => VGA_G_sig,

                        blue                                    => VGA_B_sig,

                        red_out                         => VGA_R,

                        green_out                       => VGA_G,

                        blue_out                                => VGA_B,

                        horiz_sync_out          => VGA_HS,

                        vert_sync_out           => VGA_VS,

                        video_on                                => video_on_sig,

                        pixel_clock                     => pixel_clock_sig,

                        pixel_row                       => pixel_row_sig,

                        pixel_column            => pixel_column_sig

        );

        char_rom_inst : charrom

                port map (

                        clk                                     => pixel_clock_sig,

                        character_address       => char_addr_sig,

                        font_row                                => font_row_sig,

                        font_col                                => font_col_sig,

                        rom_mux_output          => pixel_sig

        );

END A;