Subversion Repositories ag_6502

`timescale 1ns / 1ps
//////////////////////////////////////////////////////////////////////////////////
// Company:   BMSTU
// Engineer:  Oleg Odintsov
// 
// Create Date:    20:41:53 01/18/2012 
// Design Name: 
// Module Name:    videoctl 
// Project Name:    Agat Hardware Project
// Target Devices: 
// Tool versions: 
// Description: 
//
// Dependencies: 
//
// Revision: 
// Revision 0.01 - File Created
// Additional Comments: 
//
//////////////////////////////////////////////////////////////////////////////////
 
module video_counters(
		input clk,
		output reg video_vsync = 1,
		output reg video_hsync = 1,
		output video_on,
		output reg [10:1] hpos = 0,
		output reg [9:1] vpos = 0);
 
	integer hcnt = 0, vcnt = 0;
 
	reg video_von = 0, video_hon = 0;
	assign video_on = video_von & video_hon;
 
	always @(posedge video_hsync) begin
		vcnt <= vcnt + 1;
		vpos <= video_von?vpos + 1: 0;
		case (vcnt)
		2: video_vsync = 1;
		31: video_von = 1;
		511: video_von = 0;
		521: begin vcnt <=0; video_vsync = 0; end
		endcase
	end
 
	always @(posedge clk) begin
		if (!video_hon) hcnt <= hcnt - 1;
		else hpos <= hpos + 1;
 
		if (hpos == 639) video_hon <= 0;
 
		if (hpos == 640) begin
			if (!hcnt) begin
				hcnt <= 96;
				video_hsync <= 0;
				hpos <= 0;
			end
		end else if (!hcnt) begin
			if (!video_hsync) begin
				video_hsync <= 1;
				hcnt <= 48;
			end else if (!video_hon) begin
				video_hon <= 1;
				hcnt <= 16;
			end
		end
	end
endmodule