Subversion Repositories rtftextcontroller

// ============================================================================

//        __

//   \\__/ o\    (C) 2006-2022  Robert Finch, Waterloo

//    \  __ /    All rights reserved.

//     \/_//     robfinch@finitron.ca

//       ||

//

//      rfTextController.sv

//              text controller

//

// BSD 3-Clause License

// Redistribution and use in source and binary forms, with or without

// modification, are permitted provided that the following conditions are met:

//

// 1. Redistributions of source code must retain the above copyright notice, this

//    list of conditions and the following disclaimer.

//

// 2. Redistributions in binary form must reproduce the above copyright notice,

//    this list of conditions and the following disclaimer in the documentation

//    and/or other materials provided with the distribution.

//

// 3. Neither the name of the copyright holder nor the names of its

//    contributors may be used to endorse or promote products derived from

//    this software without specific prior written permission.

//

// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"

// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE

// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE

// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER 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.

//

//

//      Text Controller

//

//      FEATURES

//

//      This core requires an external timing generator to provide horizontal

//      and vertical sync signals, but otherwise can be used as a display

//  controller on it's own. However, this core may also be embedded within

//  another core such as a VGA controller.

//

//      Window positions are referenced to the rising edge of the vertical and

//      horizontal sync pulses.

//

//      The core includes an embedded dual port RAM to hold the screen

//      characters.

//

//  The controller expects a 64kB memory region to be reserved.

//

//  Memory Map:

//  0000-3FFF   display ram

//  DF00-DFFF   controller registers

//  E000-FFFF   character bitmap ram

//

//--------------------------------------------------------------------

// Registers

//

// 00h

//      7 - 0                    cccccccc  number of columns (horizontal displayed number of characters)

//      15- 8                    rrrrrrrr        number of rows (vertical displayed number of characters)

//  19-16                dddd  character output delay

//      43-32       nnnn nnnnnnnn  window left       (horizontal sync position - reference for left edge of displayed)

//      59-48       nnnn nnnnnnnn  window top        (vertical sync position - reference for the top edge of displayed)

// 01h

//       4- 0               nnnnn  maximum scan line (char ROM max value is 7)

//  11- 8                                                          wwww  pixel size - width

//  15-12                                                          hhhh  pixel size - height

//  24                      r  reset state bit

//  32                      e  controller enable

//  40                      m  multi-color mode

//  48-52               nnnnn  yscroll

//  56-60               nnnnn  xscroll

// 02h

//      23- 0   cccccccc cccccccc  color code for transparent background RGB 8,8,8 (only RGB 7,7,7 used)

//  63-32   cccc...cccc        border color ZRGB 8,8,8,8

// 03h

//      23- 0   cccccccc cccccccc  tile color code 1

//  55-32   cccccccc cccccccc  tile color code 2

// 04h

//   4- 0               eeeee    cursor end

//   7- 5                 bbb  blink control

//                             BP: 00=no blink

//                             BP: 01=no display

//                             BP: 10=1/16 field rate blink

//                             BP: 11=1/32 field rate blink

//  12- 8               sssss  cursor start

//  15-14                                                                        tt      cursor image type (box, underline, sidebar, asterisk

//  47-32   aaaaaaaa aaaaaaaa    cursor position

// 05h

//  15- 0   aaaaaaaa aaaaaaaa  start address (index into display memory)

// 07h

//      150 - - aaaaaaaa aaaaaaaa  light pen position

//--------------------------------------------------------------------

//

// ============================================================================

//`define USE_CLOCK_GATE

`define INTERNAL_RAMS   1'b1

module rfTextController_x12(

        rst_i, clk_i, cs_i,

        cti_i, cyc_i, stb_i, ack_o, wr_i, adr_i, dat_i, dat_o,

        txt_clk_o, txt_cyc_o, txt_stb_o, txt_ack_i, txt_we_o, txt_sel_o, txt_adr_o, txt_dat_o, txt_dat_i,

        cbm_clk_o, cbm_cyc_o, cbm_stb_o, cbm_ack_i, cbm_we_o, cbm_sel_o, cbm_adr_o, cbm_dat_o, cbm_dat_i,

        lp_i,

        dot_clk_i, hsync_i, vsync_i, blank_i, border_i, zrgb_i, zrgb_o, xonoff_i

);

parameter num = 4'd1;

parameter COLS = 8'd64;

parameter ROWS = 8'd32;

// Syscon

input  rst_i;                   // reset

input  clk_i;                   // clock

// Slave signals

input  cs_i;            // circuit select

input  [2:0] cti_i;

input  cyc_i;                   // valid bus cycle

input  stb_i;           // data strobe

output ack_o;                   // data acknowledge

input  wr_i;                    // write

input  [15:0] adr_i;    // address

input  [11:0] dat_i;    // data input

output reg [11:0] dat_o;        // data output

// Master Signals

output txt_clk_o;

output reg txt_cyc_o;

output reg txt_stb_o;

input txt_ack_i;

output txt_we_o;

output [7:0] txt_sel_o;

output reg [16:0] txt_adr_o;

output [63:0] txt_dat_o;

input [63:0] txt_dat_i;

output cbm_clk_o;                       // character bitmap data fetch clock

output reg cbm_cyc_o;

output reg cbm_stb_o;

input cbm_ack_i;

output cbm_we_o;

output [7:0] cbm_sel_o;

output reg [15:0] cbm_adr_o;

output [63:0] cbm_dat_o;

input [63:0] cbm_dat_i;

input lp_i;                             // light pen

// Video signals

input dot_clk_i;                // video dot clock

input hsync_i;                  // end of scan line

input vsync_i;                  // end of frame

input blank_i;                  // blanking signal

input border_i;                 // border area

input [31:0] zrgb_i;            // input pixel stream

output reg [31:0] zrgb_o;       // output pixel stream

input xonoff_i;

reg controller_enable;

reg [31:0] bkColor32, bkColor32d;       // background color

reg [31:0] fgColor32, fgColor32d;       // foreground color

wire [1:0] pix;                         // pixel value from character generator 1=on,0=off

reg por;

wire vclk;

assign txt_clk_o = vclk;

assign txt_we_o = por;

assign txt_sel_o = 8'hFF;

assign cbm_clk_o = vclk;

assign cbm_we_o = 1'b0;

assign cbm_sel_o = 8'hFF;

reg [63:0] rego;

reg [4:0] yscroll;

reg [5:0] xscroll;

reg [11:0] windowTop;

reg [11:0] windowLeft;

reg [ 7:0] numCols;

reg [ 7:0] numRows;

reg [ 7:0] charOutDelay;

reg [ 1:0] mode;

reg [ 4:0] maxRowScan;

reg [ 5:0] maxScanpix;

reg [1:0] tileWidth;            // width of tile in bytes (0=1,1=2,2=4,3=8)

reg [ 4:0] cursorStart, cursorEnd;

reg [15:0] cursorPos;

reg [1:0] cursorType;

reg [15:0] startAddress;

reg [ 2:0] rBlink;

reg [3:0] bdrCode;

wire [23:0] bdrColor;           // Border color

reg [ 3:0] pixelWidth;  // horizontal pixel width in clock cycles

reg [ 3:0] pixelHeight; // vertical pixel height in scan lines

reg mcm;                                                                // multi-color mode

wire [11:0] hctr;               // horizontal reference counter (counts clocks since hSync)

wire [11:0] scanline;   // scan line

reg [ 7:0] row;         // vertical reference counter (counts rows since vSync)

reg [ 7:0] col;         // horizontal column

reg [ 4:0] rowscan;     // scan line within row

reg [ 5:0] colscan;     // pixel column number within cell

wire nxt_row;                   // when to increment the row counter

wire nxt_col;                   // when to increment the column counter

reg [ 5:0] bcnt;                // blink timing counter

wire blink;

reg  iblank;

reg [4:0] maxScanlinePlusOne;

wire nhp;                               // next horizontal pixel

wire ld_shft = nxt_col & nhp;

// display and timing signals

reg [15:0] txtAddr;             // index into memory

reg [15:0] penAddr;

wire [23:0] screen_ram_out;             // character code

wire [23:0] txtBkColor; // background color code

wire [23:0] txtFgColor; // foreground color code

wire [5:0] txtZorder;

reg  [3:0] txtTcCode;   // transparent color code

wire [23:0] txtTcColor;

reg [3:0] tileCode1;

reg [3:0] tileCode2;

wire [23:0] tileColor1;

wire [23:0] tileColor2;

reg  bgt, bgtd;

wire [11:0] tdat_o;

wire [8:0] chdat_o;

wire [2:0] scanindex = rowscan[2:0];

//--------------------------------------------------------------------

// bus interfacing

// Address Decoding

// I/O range Dx

//--------------------------------------------------------------------

// Register the inputs

reg cs_rom, cs_reg, cs_text, cs_any;

reg [15:0] radr_i;

reg [11:0] rdat_i;

reg rwr_i;

always_ff @(posedge clk_i)

        cs_rom <= cs_i && cyc_i && stb_i && (adr_i[15:8] > 8'hDF);

always_ff @(posedge clk_i)

        cs_reg <= cs_i && cyc_i && stb_i && (adr_i[15:8] == 8'hDF);

always_ff @(posedge clk_i)

        cs_text <= cs_i && cyc_i && stb_i && (adr_i[15:8] < 8'hDF);

always_ff @(posedge clk_i)

        cs_any <= cs_i && cyc_i && stb_i;

always_ff @(posedge clk_i)

        rwr_i <= wr_i;

always_ff @(posedge clk_i)

        radr_i <= adr_i;

always_ff @(posedge clk_i)

        rdat_i <= dat_i;

// Register outputs

always @(posedge clk_i)

if (cs_i)

        casez({cs_rom,cs_reg,cs_text})

        3'b1??: dat_o <= {3'b0,chdat_o};

        3'b01?: dat_o <= rego;

        3'b001: dat_o <= tdat_o;

        default:        dat_o <= 12'h0;

        endcase

else

        dat_o <= 12'h0;

//always @(posedge clk_i)

//      if (cs_text) begin

//              $display("TC WRite: %h %h", adr_i, dat_i);

//              $stop;

//      end

// - there is a four cycle latency for reads, an ack is generated

//   after the synchronous RAM read

// - writes can be acknowledged right away.

ack_gen #(

        .READ_STAGES(5),

        .WRITE_STAGES(1),

        .REGISTER_OUTPUT(1)

)

uag1 (

        .rst_i(rst_i),

        .clk_i(clk_i),

        .ce_i(1'b1),

        .i(cs_any),

        .we_i(cs_any & rwr_i),

        .o(ack_o),

        .rid_i(0),

        .wid_i(0),

        .rid_o(),

        .wid_o()

);

//--------------------------------------------------------------------

//--------------------------------------------------------------------

`ifdef USE_CLOCK_GATE

BUFHCE ucb1 (.I(dot_clk_i), .CE(controller_enable), .O(vclk));

`else

assign vclk = dot_clk_i;

`endif

//--------------------------------------------------------------------

// Video Memory

//--------------------------------------------------------------------

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// Address Calculation:

//  - Simple: the row times the number of  cols plus the col plus the

//    base screen address

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

reg [15:0] rowcol;

always_ff @(posedge vclk)

        txtAddr <= startAddress + rowcol + col;

// Register read-back memory

// Allows reading back of register values by shadowing them with ram

wire [5:0] rrm_adr = radr_i[5:0];

wire [11:0] rrm_o;

regReadbackMem #(.WID(12)) rrm0L

(

  .wclk(clk_i),

  .adr(rrm_adr),

  .wce(cs_reg),

  .we(rwr_i),

  .i(rdat_i[11:0]),

  .o(rrm_o[11:0])

);

wire [23:0] lfsr_o;

lfsr #(24) ulfsr1(rst_i, dot_clk_i, 1'b1, 1'b0, lfsr_o);

assign m_dat_o = lfsr_o;

/*

wire pe_cs;

edge_det u1(.rst(rst_i), .clk(clk_i), .ce(1'b1), .i(cs_text), .pe(pe_cs), .ne(), .ee() );

reg [14:0] ctr;

always @(posedge clk_i)

        if (pe_cs) begin

                if (cti_i==3'b000)

                        ctr <= adr_i[16:3];

                else

                        ctr <= adr_i[16:3] + 12'd1;

                cnt <= 3'b000;

        end

        else if (cs_text && cnt[2:0]!=3'b100 && cti_i!=3'b000) begin

                ctr <= ctr + 2'd1;

                cnt <= cnt + 3'd1;

        end

reg [13:0] radr;

always @(posedge clk_i)

        radr <= pe_cs ? adr_i[16:3] : ctr;

*/

// text screen RAM

wire [13:0] bram_adr = radr_i[13:0];

`ifdef INTERNAL_RAMS

rfTextControllerRam_x12 screen_ram1

(

  .clka(clk_i),

  .ena(cs_text),

  .wea(rwr_i),

  .addra({radr_i[12:0],radr_i[13]}),

  .dina(rdat_i),

  .douta(tdat_o),

  .clkb(vclk),

  .enb(ld_shft|por),

  .web(por),

  .addrb(txtAddr[12:0]),

  .dinb({12'hE6,lfsr_o[11:0]}),

  .doutb(screen_ram_out)

);

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// Character bitmap ROM

// - room for 512 8x8 characters

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

wire [63:0] char_bmp;           // character ROM output

char_ram charRam0

(

        .clk_i(clk_i),

        .cs_i(cs_rom),

        .we_i(1'b0),

        .adr_i(radr_i[14:0]),

        .dat_i(rdat_i),

        .dat_o(chdat_o),

        .dot_clk_i(vclk),

        .ce_i(ld_shft),

        .char_code_i(screen_ram_out[8:0]),

        .maxscanline_i(maxScanlinePlusOne),

        .scanline_i(rowscan[4:0]),

        .bmp_o(char_bmp)

);

//assign char_bmp[63:9] = 55'h0;

`else

reg [63:0] char_bmp;            // character ROM output

`endif

reg [63:0] txt_dati;

reg [31:0] bmp_ndx;

`ifdef INTERNAL_RAMS

`else

always_ff @(posedge vclk)

        bmp_ndx <= (maxScanlinePlusOne * txt_dati[15:0] + rowscan[4:0]) << tileWidth;

always_ff @(posedge vclk)

begin

        if (ld_shft) begin

                txt_cyc_o <= 1'b1;

                txt_stb_o <= 1'b1;

                txt_adr_o <= {txtAddr[13:0],3'b0};

                cbm_cyc_o <= 1'b1;

                cbm_stb_o <= 1'b1;

                cbm_adr_o <= {bmp_ndx[31:3],3'b0};

        end

        if (txt_ack_i) begin

                txt_cyc_o <= 1'b0;

                txt_stb_o <= 1'b0;

                txt_dati <= txt_dat_i;

        end

        if (cbm_ack_i) begin

                cbm_cyc_o <= 1'b0;

                cbm_stb_o <= 1'b0;

                case(tileWidth)

                2'd0:   char_bmp <= cbm_dat_i >> {bmp_ndx[2:0],3'b0};

                2'd1:   char_bmp <= cbm_dat_i >> {bmp_ndx[2:1],4'b0};

                2'd2: char_bmp <= cbm_dat_i >> {bmp_ndx[2],5'b0};

                2'd3:   char_bmp <= cbm_dat_i;

                endcase

        end

end

`endif

/*

syncRam4kx9 charRam0

(

  .clka(clk_i),    // input wire clka

  .ena(cs_rom),      // input wire ena

  .wea(1'b0),//rwr_i),      // input wire [0 : 0] wea

  .addra(bram_adr),  // input wire [11 : 0] addra

  .dina(rdat_i[8:0]),    // input wire [8 : 0] dina

  .douta(chdat_o),  // output wire [8 : 0] douta

  .clkb(vclk),    // input wire clkb

  .enb(ld_shft),      // input wire enb

  .web(1'b0),      // input wire [0 : 0] web

  .addrb({screen_ram_out[8:0],scanline[2:0]}),  // input wire [11 : 0] addrb

  .dinb(9'h0),    // input wire [8 : 0] dinb

  .doutb(char_bmp)  // output wire [8 : 0] doutb

);

*/

// pipeline delay - sync color with character bitmap output

reg [5:0] txtZorder1;

wire [3:0] txtBkCode1 = screen_ram_out[15:12];

wire [3:0] txtFgCode1 = screen_ram_out[19:16];

rfColorROM ucr1(vclk, ld_shft, {1'b0,txtBkCode1}, txtBkColor);

rfColorROM ucr2(vclk, ld_shft, {1'b0,txtFgCode1}, txtFgColor);

rfColorROM ucr3(vclk, 1'b1, {1'b0,txtTcCode}, txtTcColor);

rfColorROM ucr4(vclk, 1'b1, {1'b0,bdrCode}, bdrColor);

rfColorROM ucr5(vclk, ld_shft, {1'b0,tileCode1}, tileColor1);

rfColorROM ucr6(vclk, ld_shft, {1'b0,tileCode2}, tileColor2);

always @(posedge vclk)

        if (ld_shft) txtZorder1 <= 6'h3F;

//--------------------------------------------------------------------

// Light Pen

//--------------------------------------------------------------------

wire lpe;

edge_det u1 (.rst(rst_i), .clk(clk_i), .ce(1'b1), .i(lp_i), .pe(lpe), .ne(), .ee() );

always @(posedge clk_i)

        if (rst_i)

                penAddr <= 32'h0000_0000;

        else begin

                if (lpe)

                        penAddr <= txtAddr;

        end

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// Register read port

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

always @*

        if (cs_reg) begin

                case(radr_i[5:0])

                6'd56:    rego <= {8'h00,penAddr[15:12]};

                6'd57:    rego <= penAddr[11:0];

                default:        rego <= rrm_o;

                endcase

        end

        else

                rego <= 12'h000;

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

// Register write port

//- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

always @(posedge clk_i)

        if (rst_i) begin

          por <= 1'b1;

          mcm <= 1'b0;

          controller_enable <= 1'b1;

    xscroll              <= 6'd0;

    yscroll              <= 5'd0;

    txtTcCode    <= 4'hE;

    bdrCode      <= 4'hE;

    startAddress <= 16'h0000;

    cursorStart  <= 5'd00;

    cursorEnd    <= 5'd31;

    cursorPos    <= 16'h0003;

    cursorType   <= 2'b00;

// 104x63

/*

                windowTop    <= 12'd26;

                windowLeft   <= 12'd260;

                pixelWidth   <= 4'd0;

                pixelHeight  <= 4'd1;           // 525 pixels (408 with border)

*/

// 52x31

/*

                // 84x47

                windowTop    <= 12'd16;

                windowLeft   <= 12'd90;

                pixelWidth   <= 4'd1;           // 681 pixels

                pixelHeight  <= 4'd1;           // 384 pixels

*/

                // 48x29

                if (num==4'd1) begin

      windowTop    <= 12'd4058;//12'd16;

      windowLeft   <= 12'd3956;//12'd3930;//12'd86;

      pixelWidth   <= 4'd0;             // 800 pixels

      pixelHeight  <= 4'd0;             // 600 pixels

      numCols      <= COLS;

      numRows      <= ROWS;

      maxRowScan  <= 5'd17;

      maxScanpix   <= 6'd11;

      rBlink       <= 3'b111;           // 01 = non display

      charOutDelay <= 8'd5;

                end

                else if (num==4'd2) begin

      windowTop    <= 12'd4032;//12'd16;

      windowLeft   <= 12'd3720;//12'd86;

      pixelWidth   <= 4'd0;        // 800 pixels

      pixelHeight  <= 4'd0;        // 600 pixels

      numCols      <= 40;

      numRows      <= 25;

      maxRowScan  <= 5'd7;

      maxScanpix   <= 6'd7;

      rBlink       <= 3'b111;        // 01 = non display

      charOutDelay <= 8'd6;

                end

        end

        else begin

                if (bcnt > 6'd10)

                        por <= 1'b0;

                if (cs_reg & rwr_i) begin       // register write ?

                        $display("TC Write: r%d=%h", rrm_adr, rdat_i);

                        case(radr_i[5:0])

                        6'd0:   numCols <= rdat_i[7:0];

                        6'd1:   numRows <= rdat_i[7:0];

                        6'd2:   charOutDelay <= rdat_i;

                        6'd4:   ;

                        6'd5:   windowLeft[11:0] <= rdat_i;

                        6'd6:   ;

                        6'd7:   windowTop[11:0] <= rdat_i;

                        6'd8:   maxRowScan <= rdat_i[4:0];

                        6'd9:

                                begin

                                                pixelHeight <= rdat_i[7:4];

                                                pixelWidth  <= rdat_i[3:0];     // horizontal pixel width

                                end

                        6'd11:  por <= rdat_i[0];

                        6'd12:  controller_enable <= rdat_i[0];

                        6'd13:  mcm <= rdat_i[0];

                        6'd14:  yscroll <= rdat_i[4:0];

                        6'd15:  xscroll <= rdat_i[5:0];

                        6'd16:  txtTcCode <= rdat_i[7:0];

                        6'd20:  bdrCode <= rdat_i[7:0];

                        6'd24:  tileCode1 <= rdat_i[7:0];

                        6'd28:  tileCode2 <= rdat_i[7:0];

                        6'd31:  maxScanpix <= rdat_i[5:0];

                        6'd32:

                                begin

                                                cursorEnd <= rdat_i[4:0];       // scan line sursor starts on

                                                rBlink      <= rdat_i[7:5];

                                end

                        6'd33:

                                        begin

                                                cursorStart <= rdat_i[4:0];     // scan line cursor ends on

                                                cursorType  <= rdat_i[7:6];

                                        end

                        6'd34:  cursorPos[15:12] <= rdat_i[3:0];

                        6'd35:  cursorPos[11: 0] <= rdat_i;

                        6'd40:  startAddress[15:12] <= rdat_i[3:0];

                        6'd41:  startAddress[11: 0] <= rdat_i;

                        default: ;

                        endcase

                end

        end

//--------------------------------------------------------------------

//--------------------------------------------------------------------

// "Box" cursor bitmap

reg [7:0] curout;

always @*

        case({cursorType,scanindex})

        // Box cursor

        5'b00_000:      curout = 8'b11111110;

        5'b00_001:      curout = 8'b10000010;

        5'b00_010:      curout = 8'b10000010;

        5'b00_011:      curout = 8'b10000010;

        5'b00_100:      curout = 8'b10000010;

        5'b00_101:      curout = 8'b10000010;

        5'b00_110:      curout = 8'b10010010;

        5'b00_111:      curout = 8'b11111110;

        // vertical bar cursor

        5'b01_000:      curout = 8'b11000000;

        5'b01_001:      curout = 8'b10000000;

        5'b01_010:      curout = 8'b10000000;

        5'b01_011:      curout = 8'b10000000;

        5'b01_100:      curout = 8'b10000000;

        5'b01_101:      curout = 8'b10000000;

        5'b01_110:      curout = 8'b10000000;

        5'b01_111:      curout = 8'b11000000;

        // underline cursor

        5'b10_000:      curout = 8'b00000000;

        5'b10_001:      curout = 8'b00000000;

        5'b10_010:      curout = 8'b00000000;

        5'b10_011:      curout = 8'b00000000;

        5'b10_100:      curout = 8'b00000000;

        5'b10_101:      curout = 8'b00000000;

        5'b10_110:      curout = 8'b00000000;

        5'b10_111:      curout = 8'b11111111;

        // Asterisk

        5'b11_000:      curout = 8'b00000000;

        5'b11_001:      curout = 8'b00000000;

        5'b11_010:      curout = 8'b00100100;

        5'b11_011:      curout = 8'b00011000;

        5'b11_100:      curout = 8'b01111110;

        5'b11_101:      curout = 8'b00011000;

        5'b11_110:      curout = 8'b00100100;

        5'b11_111:      curout = 8'b00000000;

        endcase

//-------------------------------------------------------------

// Video Stuff

//-------------------------------------------------------------

wire pe_hsync;

wire pe_vsync;

edge_det edh1

(

        .rst(rst_i),

        .clk(vclk),

        .ce(1'b1),

        .i(hsync_i),

        .pe(pe_hsync),

        .ne(),

        .ee()

);

edge_det edv1

(

        .rst(rst_i),

        .clk(vclk),

        .ce(1'b1),

        .i(vsync_i),

        .pe(pe_vsync),

        .ne(),

        .ee()

);

// Horizontal counter:

//

/*

HVCounter uhv1

(

        .rst(rst_i),

        .vclk(vclk),

        .pixcce(1'b1),

        .sync(hsync_i),

        .cnt_offs(windowLeft),

        .pixsz(pixelWidth),

        .maxpix(maxScanpix),

        .nxt_pix(nhp),

        .pos(col),

        .nxt_pos(nxt_col),

        .ctr(hctr)

);

*/

// Vertical counter:

//

/*

HVCounter uhv2

(

        .rst(rst_i),

        .vclk(vclk),

        .pixcce(pe_hsync),

        .sync(vsync_i),

        .cnt_offs(windowTop),

        .pixsz(pixelHeight),

        .maxpix(maxRowScan),

        .nxt_pix(),

        .pos(row),

        .nxt_pos(nxt_row),

        .ctr(scanline)

);

*/

// We generally don't care about the exact reset point, unless debugging in

// simulation. The counters will eventually cycle to a proper state. A little

// bit of logic / routing can be avoided by omitting the reset.

`ifdef SIM

wire sym_rst = rst_i;

`else

wire sym_rst = 1'b0;

`endif

// Raw scanline counter

vid_counter #(12) u_vctr (.rst(sym_rst), .clk(vclk), .ce(pe_hsync), .ld(pe_vsync), .d(windowTop), .q(scanline), .tc());

vid_counter #(12) u_hctr (.rst(sym_rst), .clk(vclk), .ce(1'b1), .ld(pe_hsync), .d(windowLeft), .q(hctr), .tc());

// Vertical pixel height counter, synchronized to scanline #0

reg [3:0] vpx;

wire nvp = vpx==pixelHeight;

always @(posedge vclk)

if (sym_rst)

        vpx <= 4'b0;

else begin

        if (pe_hsync) begin

                if (scanline==12'd0)

                        vpx <= 4'b0;

                else if (nvp)

                        vpx <= 4'd0;

                else

                        vpx <= vpx + 4'd1;

        end

end

reg [3:0] hpx;

assign nhp = hpx==pixelWidth;

always @(posedge vclk)

if (sym_rst)

        hpx <= 4'b0;

else begin

        if (hctr==12'd0)

                hpx <= 4'b0;

        else if (nhp)

                hpx <= 4'd0;

        else

                hpx <= hpx + 4'd1;

end

// The scanline row within a character bitmap

always @(posedge vclk)

if (sym_rst)

        rowscan <= 5'd0;

else begin

        if (pe_hsync & nvp) begin

                if (scanline==12'd0)

                        rowscan <= yscroll;

                else if (rowscan==maxRowScan)

                        rowscan <= 5'd0;

                else

                        rowscan <= rowscan + 5'd1;

        end

end

assign nxt_col = colscan==maxScanpix;

always @(posedge vclk)

if (sym_rst)

        colscan <= 6'd0;

else begin

        if (nhp) begin

                if (hctr==12'd0)

                        colscan <= xscroll;

                else if (nxt_col)

                        colscan <= 6'd0;

                else

                        colscan <= colscan + 2'd1;

        end

end

// The screen row

always @(posedge vclk)

if (sym_rst)

        row <= 8'd0;

else begin

        if (pe_hsync & nvp) begin

                if (scanline==12'd0)

                        row <= 8'd0;

                else if (rowscan==maxRowScan)

                        row <= row + 8'd1;

        end

end

// The screen column

always @(posedge vclk)

if (sym_rst)

        col <= 8'd0;

else begin

        if (hctr==12'd0)

                col <= 8'd0;

        else if (nhp) begin

                if (nxt_col)

                        col <= col + 8'd1;

        end

end

// More useful, the offset of the start of the text display on a line.

always @(posedge vclk)

if (sym_rst)

        rowcol <= 16'd0;

else begin

        if (pe_hsync & nvp) begin

                if (scanline==12'd0)

                        rowcol <= 8'd0;

                else if (rowscan==maxRowScan)

                        rowcol <= rowcol + numCols;

        end

end

// Takes 3 clock for scanline to become stable, but should be stable before any

// chars are displayed.

reg [13:0] rxmslp1;

always @(posedge vclk)

        maxScanlinePlusOne <= maxRowScan + 4'd1;

//always @(posedge vclk)

//      rxmslp1 <= row * maxScanlinePlusOne;

//always @(posedge vclk)

//      scanline <= scanline - rxmslp1;

// Blink counter

//

always @(posedge vclk)

if (sym_rst)

        bcnt <= 6'd0;

else begin

        if (pe_vsync)

                bcnt <= bcnt + 6'd1;

end

reg blink_en;

always @(posedge vclk)

        blink_en <= (cursorPos+4==txtAddr) && (rowscan[4:0] >= cursorStart) && (rowscan[4:0] <= cursorEnd);

VT151 ub2

(

        .e_n(!blink_en),

        .s(rBlink),

        .i0(1'b1), .i1(1'b0), .i2(bcnt[4]), .i3(bcnt[5]),

        .i4(1'b1), .i5(1'b0), .i6(bcnt[4]), .i7(bcnt[5]),

        .z(blink),

        .z_n()

);

always @(posedge vclk)

        if (ld_shft)

                bkColor32 <= {txtZorder1,2'b00,txtBkColor};

always @(posedge vclk)

        if (nhp)

                bkColor32d <= bkColor32;

always @(posedge vclk)

        if (ld_shft)

                fgColor32 <= {txtZorder1,2'b00,txtFgColor};

always @(posedge vclk)

        if (nhp)

                fgColor32d <= fgColor32;

always @(posedge vclk)

        if (ld_shft)

                bgt <= txtBkCode1==txtTcCode;

always @(posedge vclk)

        if (nhp)

                bgtd <= bgt;

// Convert character bitmap to pixels

reg [63:0] charout1;

always @(posedge vclk)

        charout1 <= blink ? (char_bmp ^ curout) : char_bmp;

// Convert parallel to serial

ParallelToSerial ups1

(

        .rst(rst_i),

        .clk(vclk),

        .mcm(mcm),

        .ce(nhp),

        .ld(ld_shft),

        .a(maxScanpix[5:3]),

        .qin(2'b0),

        .d(charout1),

        .qh(pix)

);

/*

always_ff @(posedge vclk)

if (rst_i) begin

        pix <= 64'd0;

end

else begin

        if (nhp) begin

                if (ld_shft)

                        pix <= charout1;

                else begin

                        if (mcm)

                                pix <= {2'b00,pix[63:2]};

                        else

                                pix <= {1'b0,pix[63:1]};

                end

        end

end

*/

reg [1:0] pix1;

always_ff @(posedge vclk)

        if (nhp)

    pix1 <= pix[1:0];