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/////////////////////////////////////////////////////////////////////
////                                                             ////
////  WISHBONE rev.B2 compliant enhanced VGA/LCD Core            ////
////  Wishbone slave interface                                   ////
////                                                             ////
////  Author: Richard Herveille                                  ////
////          richard@asics.ws                                   ////
////          www.asics.ws                                       ////
////                                                             ////
////  Downloaded from: http://www.opencores.org/projects/vga_lcd ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
////                                                             ////
//// Copyright (C) 2001, 2002 Richard Herveille                  ////
////                    richard@asics.ws                         ////
////                                                             ////
//// This source file may be used and distributed without        ////
//// restriction provided that this copyright statement is not   ////
//// removed from the file and that any derivative work contains ////
//// the original copyright notice and the associated disclaimer.////
////                                                             ////
////     THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY     ////
//// EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED   ////
//// TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS   ////
//// FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL THE AUTHOR      ////
//// OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,         ////
//// INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES    ////
//// (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE   ////
//// GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR        ////
//// BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF  ////
//// LIABILITY, WHETHER IN  CONTRACT, STRICT LIABILITY, OR TORT  ////
//// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT  ////
//// OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE         ////
//// POSSIBILITY OF SUCH DAMAGE.                                 ////
////                                                             ////
/////////////////////////////////////////////////////////////////////
 
//  CVS Log
//
//  $Id: vga_wb_slave.v,v 1.8 2002-03-04 11:01:59 rherveille Exp $
//
//  $Date: 2002-03-04 11:01:59 $
//  $Revision: 1.8 $
//  $Author: rherveille $
//  $Locker:  $
//  $State: Exp $
//
// Change History:
//               $Log: not supported by cvs2svn $
//               Revision 1.7  2002/02/25 06:13:44  rherveille
//               Fixed dat_o incomplete sensitivity list.
//
//               Revision 1.6  2002/02/07 05:42:10  rherveille
//               Fixed some bugs discovered by modified testbench
//               Removed / Changed some strange logic constructions
//               Started work on hardware cursor support (not finished yet)
//               Changed top-level name to vga_enh_top.v
//
 
 
`include "timescale.v"
`include "vga_defines.v"
 
module vga_wb_slave(clk_i, rst_i, arst_i, adr_i, dat_i, dat_o, sel_i, we_i, stb_i, cyc_i, ack_o, err_o, inta_o,
		bl, csl, vsl, hsl, pc, cd, vbl, cbsw, vbsw, ven, avmp, acmp, 
		cursor0_res, cursor0_en, cursor0_xy, cursor0_ba, cursor0_ld, cc0_adr_i, cc0_dat_o, 
		cursor1_res, cursor1_en, cursor1_xy, cursor1_ba, cursor1_ld, cc1_adr_i, cc1_dat_o,
		vbsint_in, cbsint_in, hint_in, vint_in, luint_in, sint_in,
		Thsync, Thgdel, Thgate, Thlen, Tvsync, Tvgdel, Tvgate, Tvlen, VBARa, VBARb, clut_acc, clut_ack, clut_q);
 
	//
	// inputs & outputs
	//
 
	// wishbone slave interface
	input         clk_i;
	input         rst_i;
	input         arst_i;
	input  [11:2] adr_i;
	input  [31:0] dat_i;
	output [31:0] dat_o;
	reg [31:0] dat_o;
	input  [ 3:0] sel_i;
	input         we_i;
	input         stb_i;
	input         cyc_i;
	output        ack_o;
	reg ack_o;
	output        err_o;
	reg err_o;
	output        inta_o;
	reg inta_o;
 
	// control register settings
	output bl;         // blanking level
	output csl;        // composite sync level
	output vsl;        // vsync level
	output hsl;        // hsync level
	output pc;         // pseudo color
	output [1:0] cd;   // color depth
	output [1:0] vbl;  // video memory burst length
	output cbsw;       // clut bank switch enable
	output vbsw;       // video memory bank switch enable
	output ven;        // video system enable
 
	// hardware cursor settings
	output         cursor0_res;  // cursor0 resolution
	output         cursor0_en;   // cursor0 enable
	output [31: 0] cursor0_xy;   // cursor0 location
	output [31:11] cursor0_ba;   // cursor0 base address
	output         cursor0_ld;   // reload cursor0 from video memory
	input  [ 3: 0] cc0_adr_i;    // cursor0 color register address
	output [15: 0] cc0_dat_o;    // cursor0 color register data
	output         cursor1_res;  // cursor1 resolution
	output         cursor1_en;   // cursor1 enable
	output [31: 0] cursor1_xy;   // cursor1 location
	output [31:11] cursor1_ba;   // cursor1 base address
	output         cursor1_ld;   // reload cursor1 from video memory
	input  [ 3: 0] cc1_adr_i;    // cursor1 color register address
	output [15: 0] cc1_dat_o;    // cursor1 color register data
 
	reg [31: 0] cursor0_xy;
	reg [31:11] cursor0_ba;
	reg         cursor0_ld;
	reg [31: 0] cursor1_xy;
	reg [31:11] cursor1_ba;
	reg         cursor1_ld;
 
	// status register inputs
	input avmp;          // active video memory page
	input acmp;          // active clut memory page
	input vbsint_in;     // bank switch interrupt request
	input cbsint_in;     // clut switch interrupt request
	input hint_in;       // hsync interrupt request
	input vint_in;       // vsync interrupt request
	input luint_in;      // line fifo underrun interrupt request
	input sint_in;       // system error interrupt request
 
	// Horizontal Timing Register
	output [ 7:0] Thsync;
	output [ 7:0] Thgdel;
	output [15:0] Thgate;
	output [15:0] Thlen;
 
	// Vertical Timing Register
	output [ 7:0] Tvsync;
	output [ 7:0] Tvgdel;
	output [15:0] Tvgate;
	output [15:0] Tvlen;
 
	// video base addresses
	output [31:2] VBARa;
	reg [31:2] VBARa;
	output [31:2] VBARb;
	reg [31:2] VBARb;
 
	// color lookup table signals
	output        clut_acc;
	input         clut_ack;
	input  [23:0] clut_q;
 
 
	//
	// variable declarations
	//
	parameter REG_ADR_HIBIT = 7;
 
	wire [REG_ADR_HIBIT:0] REG_ADR  = adr_i[REG_ADR_HIBIT : 2];
	wire                   CLUT_ADR = adr_i[11];
 
	parameter [REG_ADR_HIBIT : 0] CTRL_ADR  = 6'b00_0000;
	parameter [REG_ADR_HIBIT : 0] STAT_ADR  = 6'b00_0001;
	parameter [REG_ADR_HIBIT : 0] HTIM_ADR  = 6'b00_0010;
	parameter [REG_ADR_HIBIT : 0] VTIM_ADR  = 6'b00_0011;
	parameter [REG_ADR_HIBIT : 0] HVLEN_ADR = 6'b00_0100;
	parameter [REG_ADR_HIBIT : 0] VBARA_ADR = 6'b00_0101;
	parameter [REG_ADR_HIBIT : 0] VBARB_ADR = 6'b00_0110;
	parameter [REG_ADR_HIBIT : 0] C0XY_ADR  = 6'b00_1100;
	parameter [REG_ADR_HIBIT : 0] C0BAR_ADR = 6'b00_1101;
	parameter [REG_ADR_HIBIT : 0] CCR0_ADR  = 6'b01_0???;
	parameter [REG_ADR_HIBIT : 0] C1XY_ADR  = 6'b01_1100;
	parameter [REG_ADR_HIBIT : 0] C1BAR_ADR = 6'b01_1101;
	parameter [REG_ADR_HIBIT : 0] CCR1_ADR  = 6'b10_0???;
 
 
	reg [31:0] ctrl, stat, htim, vtim, hvlen;
	wire hint, vint, vbsint, cbsint, luint, sint;
	wire hie, vie, vbsie, cbsie;
	wire acc, acc32, reg_acc, reg_wacc;
	wire cc0_acc, cc1_acc;
	wire [31:0] ccr0_dat_o, ccr1_dat_o;
 
 
	reg [31:0] reg_dato; // data output from registers
 
	//
	// Module body
	//
 
	assign acc      =  cyc_i & stb_i;
	assign acc32    = (sel_i == 4'b1111);
	assign clut_acc =  CLUT_ADR & acc & acc32;
	assign reg_acc  = !CLUT_ADR & acc & acc32;
	assign reg_wacc =  reg_acc & we_i;
 
	assign cc0_acc  = CCR0_ADR & acc & acc32;
	assign cc1_acc  = CCR1_ADR & acc & acc32;
 
	always@(posedge clk_i)
		ack_o <= #1 ((reg_acc & acc32) | clut_ack) & !ack_o;
 
	always@(posedge clk_i)
		err_o <= #1 acc & !acc32 & !err_o;
 
 
	// generate registers
	always@(posedge clk_i or negedge arst_i)
	begin : gen_regs
		if(!arst_i)
			begin
				htim       <= #1 0;
				vtim       <= #1 0;
				hvlen      <= #1 0;
				VBARa      <= #1 0;
				VBARb      <= #1 0;
				cursor0_xy <= #1 0;
				cursor0_ba <= #1 0;
				cursor1_xy <= #1 0;
				cursor1_ba <= #1 0;
			end
		else if (rst_i)
			begin
				htim       <= #1 0;
				vtim       <= #1 0;
				hvlen      <= #1 0;
				VBARa      <= #1 0;
				VBARb      <= #1 0;
				cursor0_xy <= #1 0;
				cursor0_ba <= #1 0;
				cursor1_xy <= #1 0;
				cursor1_ba <= #1 0;
			end
		else if (reg_wacc)
			case (adr_i)	// synopsis full_case parallel_case
				HTIM_ADR  : htim       <= #1 dat_i;
				VTIM_ADR  : vtim       <= #1 dat_i;
				HVLEN_ADR : hvlen      <= #1 dat_i;
				VBARA_ADR : VBARa      <= #1 dat_i[31: 2];
				VBARB_ADR : VBARb      <= #1 dat_i[31: 2];
				C0XY_ADR  : cursor0_xy <= #1 dat_i[31: 0];
				C0BAR_ADR : cursor0_ba <= #1 dat_i[31:11];
				C1XY_ADR  : cursor1_xy <= #1 dat_i[31: 0];
				C1BAR_ADR : cursor1_ba <= #1 dat_i[31:11];
			endcase
	end
 
	always@(posedge clk_i)
		begin
			cursor0_ld <= #1 reg_wacc && (adr_i == C0BAR_ADR);
			cursor1_ld <= #1 reg_wacc && (adr_i == C1BAR_ADR);
		end
 
	// generate control register
	always@(posedge clk_i or negedge arst_i)
		if (!arst_i)
			ctrl <= #1 0;
		else if (rst_i)
			ctrl <= #1 0;
		else if (reg_wacc & (REG_ADR == CTRL_ADR) )
			ctrl <= #1 dat_i;
		else
			begin
				ctrl[6] <= #1 ctrl[6] & !cbsint_in;
				ctrl[5] <= #1 ctrl[5] & !vbsint_in;
			end
 
 
	// generate status register
	always@(posedge clk_i or negedge arst_i)
		if (!arst_i)
			stat <= #1 0;
		else if (rst_i)
			stat <= #1 0;
		else
			begin
				`ifdef VGA_HWC1
					stat[21] <= #1 1'b1;
				`else
					stat[21] <= #1 1'b0;
				`endif
				`ifdef VGA_HWC0
					stat[20] <= #1 1'b1;
				`else
					stat[20] <= #1 1'b0;
				`endif
 
				stat[17] <= #1 acmp;
				stat[16] <= #1 avmp;
 
				if (reg_wacc & (REG_ADR == STAT_ADR) )
					begin
						stat[7] <= #1 cbsint_in | (stat[7] & !dat_i[7]);
						stat[6] <= #1 vbsint_in | (stat[6] & !dat_i[6]);
						stat[5] <= #1 hint_in   | (stat[5] & !dat_i[5]);
						stat[4] <= #1 vint_in   | (stat[4] & !dat_i[4]);
						stat[1] <= #1 luint_in  | (stat[3] & !dat_i[1]);
						stat[0] <= #1 sint_in   | (stat[0] & !dat_i[0]);
					end
				else
					begin
						stat[7] <= #1 stat[7] | cbsint_in;
						stat[6] <= #1 stat[6] | vbsint_in;
						stat[5] <= #1 stat[5] | hint_in;
						stat[4] <= #1 stat[4] | vint_in;
						stat[1] <= #1 stat[1] | luint_in;
						stat[0] <= #1 stat[0] | sint_in;
					end
			end
 
 
	// decode control register
	assign cursor1_res = ctrl[25];
	assign cursor1_en  = ctrl[24];
	assign cursor0_res = ctrl[23];
	assign cursor0_en  = ctrl[20];
	assign bl          = ctrl[15];
	assign csl         = ctrl[14];
	assign vsl         = ctrl[13];
	assign hsl         = ctrl[12];
	assign pc          = ctrl[11];
	assign cd          = ctrl[10:9];
	assign vbl         = ctrl[8:7];
	assign cbsw        = ctrl[6];
	assign vbsw        = ctrl[5];
	assign cbsie       = ctrl[4];
	assign vbsie       = ctrl[3];
	assign hie         = ctrl[2];
	assign vie         = ctrl[1];
	assign ven         = ctrl[0];
 
	// decode status register
	assign cbsint = stat[7];
	assign vbsint = stat[6];
	assign hint   = stat[5];
	assign vint   = stat[4];
	assign luint  = stat[1];
	assign sint   = stat[0];
 
	// decode Horizontal Timing Register
	assign Thsync = htim[31:24];
	assign Thgdel = htim[23:16];
	assign Thgate = htim[15:0];
	assign Thlen  = hvlen[31:16];
 
	// decode Vertical Timing Register
	assign Tvsync = vtim[31:24];
	assign Tvgdel = vtim[23:16];
	assign Tvgate = vtim[15:0];
	assign Tvlen  = hvlen[15:0];
 
 
	`ifdef VGA_HWC0
		// hookup cursor0 color registers
		vga_cur_cregs cregs0(
			.clk_i(clk_i),
			.rst_i(rst_i),
			.arst_i(arst_i),
			.hsel_i(cc0_acc),
			.hadr_i(adr_i[4:2]),
			.hwe_i(we_i),
			.hdat_i(dat_i),
			.hdat_o(ccr0_dat_o), // host access
			.hack_o(),
			.cadr_i(cc0_adr_i),
			.cdat_o(cc0_dat_o)   // cursor processor access
		);
	`else
		assign ccr0_dat_0 = 32'h0;
	`endif
 
	`ifdef VGA_HWC1
		// hookup cursor1 color registers
		vga_cur_cregs cregs1(
			.clk_i(clk_i),
			.rst_i(rst_i),
			.arst_i(arst_i),
			.hsel_i(cc1_acc),
			.hadr_i(adr_i[4:2]),
			.hwe_i(we_i),
			.hdat_i(dat_i),
			.hdat_o(ccr1_dat_o), // host access
			.hack_o(),
			.cadr_i(cc1_adr_i),
			.cdat_o(cc1_dat_o)   // cursor processor access
		);
	`else
		assign ccr1_dat_o = 32'h0;
	`endif
 
 
	// assign output
	always@(REG_ADR or ctrl or stat or htim or vtim or hvlen or VBARa or VBARb or acmp or
		cursor0_xy or cursor0_ba or cursor1_xy or cursor1_ba)
	casez (REG_ADR) // synopsis full_case parallel_case
		CTRL_ADR  : reg_dato = ctrl;
		STAT_ADR  : reg_dato = stat;
		HTIM_ADR  : reg_dato = htim;
		VTIM_ADR  : reg_dato = vtim;
		HVLEN_ADR : reg_dato = hvlen;
		VBARA_ADR : reg_dato = {VBARa, 2'b0};
		VBARB_ADR : reg_dato = {VBARb, 2'b0};
		C0XY_ADR  : reg_dato = cursor0_xy;
		C0BAR_ADR : reg_dato = {cursor0_ba, 11'h0};
		CCR0_ADR  : reg_dato = ccr0_dat_o;
		C1XY_ADR  : reg_dato = cursor1_xy;
		C1BAR_ADR : reg_dato = {cursor1_ba, 11'h0};
		CCR1_ADR  : reg_dato = ccr1_dat_o;
		default   : reg_dato = 32'h0000_0000;
	endcase
 
	always@(posedge clk_i)
		dat_o <= #1 reg_acc ? reg_dato : {8'h0, clut_q};
 
	// generate interrupt request signal
	always@(posedge clk_i)
		inta_o <= #1 (hint & hie) | (vint & vie) | (vbsint & vbsie) | (cbsint & cbsie) | luint | sint;
endmodule