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;