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  1. // ZX-Evo Base Configuration (c) NedoPC 2008,2009,2010,2011,2012,2013,2014
  2. //
  3. // mix up border and pixels, add palette and blanks
  4.  
  5. /*
  6.     This file is part of ZX-Evo Base Configuration firmware.
  7.  
  8.     ZX-Evo Base Configuration firmware is free software:
  9.     you can redistribute it and/or modify it under the terms of
  10.     the GNU General Public License as published by
  11.     the Free Software Foundation, either version 3 of the License, or
  12.     (at your option) any later version.
  13.  
  14.     ZX-Evo Base Configuration firmware is distributed in the hope that
  15.     it will be useful, but WITHOUT ANY WARRANTY; without even
  16.     the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
  17.     See the GNU General Public License for more details.
  18.  
  19.     You should have received a copy of the GNU General Public License
  20.     along with ZX-Evo Base Configuration firmware.
  21.     If not, see <http://www.gnu.org/licenses/>.
  22. */
  23.  
  24. `include "../include/tune.v"
  25.  
  26. module video_palframe(
  27.  
  28.         input  wire        clk, // 28MHz clock
  29.  
  30.  
  31.         input  wire        hpix,
  32.         input  wire        vpix,
  33.  
  34.         input  wire        hblank,
  35.         input  wire        vblank,
  36.  
  37.         input  wire        hsync_start,
  38.         input  wire        vsync,
  39.  
  40.         input  wire [ 3:0] pixels,
  41.         input  wire [ 3:0] border,
  42.  
  43.         input  wire        border_sync,
  44.         input  wire        border_sync_ena,
  45.  
  46.         // ulaplus related
  47.         input  wire [ 1:0] up_palsel,
  48.         input  wire [ 2:0] up_paper,
  49.         input  wire [ 2:0] up_ink,
  50.         input  wire        up_pixel,
  51.  
  52.         input  wire        up_ena,
  53.         input  wire        up_palwr,
  54.         input  wire [ 5:0] up_paladdr,
  55.         input  wire [ 7:0] up_paldata,
  56.  
  57.         input  wire        atm_palwr,
  58.         input  wire [ 5:0] atm_paldata,
  59.  
  60.  
  61.         output wire [ 5:0] palcolor, // just for palette readback
  62.  
  63.         output wire [ 5:0] color
  64. );
  65.         reg [7:0] palette_read;
  66.  
  67.         wire [ 3:0] zxcolor;
  68.         wire [ 5:0] up_color;
  69.         wire [ 8:0] palette_color;
  70.  
  71.         reg [3:0] synced_border;
  72.  
  73.         reg vsync_r;
  74.         reg [1:0] ctr_14;
  75.         reg ctr_h;
  76.         reg ctr_v;
  77.  
  78.  
  79.         always @(posedge clk)
  80.         if( border_sync )
  81.                 synced_border <= border;
  82.  
  83.         assign zxcolor = (hpix&vpix) ? pixels : (border_sync_ena ? synced_border : border);
  84.  
  85.         assign up_color = (hpix&vpix) ? {up_palsel,~up_pixel,up_pixel?up_ink:up_paper} : {3'd0,border[2:0]};
  86.  
  87.         assign palette_color = up_ena ? {3'b100,up_color} : {5'd0,zxcolor};
  88.  
  89.  
  90.         // palette
  91.         reg [7:0] palette [0:511]; // let quartus instantiate it as RAM
  92.  
  93.         always @(posedge clk)
  94.         begin
  95.                 if( atm_palwr || up_palwr )
  96.                 begin : palette_write
  97.                         reg [8:0] pal_addr;
  98.                         pal_addr = atm_palwr ? { 5'd0, zxcolor } : { 3'b100, up_paladdr };
  99.  
  100.                         palette[pal_addr] <= atm_palwr ? {atm_paldata[3:2],1'b0,atm_paldata[5:4],1'b0,atm_paldata[1:0]} : up_paldata;
  101.                 end
  102.  
  103.                 palette_read <= palette[palette_color];
  104.         end
  105.  
  106.  
  107.         assign palcolor = {palette_read[4:3],palette_read[7:6], palette_read[1:0]};
  108.  
  109.  
  110.  
  111.  
  112.         // make 3bit palette
  113.         always @(posedge clk)
  114.                 vsync_r <= vsync;
  115.         //
  116.         wire vsync_start = vsync && !vsync_r;
  117.         //
  118.         initial ctr_14 = 2'b00;
  119.         always @(posedge clk)
  120.                 ctr_14 <= ctr_14+2'b01;
  121.         //
  122.         initial ctr_h = 1'b0;
  123.         always @(posedge clk) if( hsync_start )
  124.                 ctr_h <= ~ctr_h;
  125.         //
  126.         initial ctr_v = 1'b0;
  127.         always @(posedge clk) if( vsync_start )
  128.                 ctr_v <= ~ctr_v;
  129.  
  130.  
  131.         wire plus1 = ctr_14[1] ^ ctr_h ^ ctr_v;
  132.  
  133.  
  134.  
  135.         wire [1:0] red;
  136.         wire [1:0] grn;
  137.         wire [1:0] blu;
  138.  
  139.         video_palframe_mk3bit red_color
  140.         (
  141.                 .plus1    (plus1            ),
  142.                 .color_in (palette_read[7:5]),
  143.                 .color_out(red              )
  144.         );
  145.         //
  146.         video_palframe_mk3bit grn_color
  147.         (
  148.                 .plus1    (plus1            ),
  149.                 .color_in (palette_read[4:2]),
  150.                 .color_out(grn              )
  151.         );
  152.         //
  153.         assign blu = palette_read[1:0];
  154.  
  155.         assign color = (hblank | vblank) ? 6'd0 : {grn,red,blu};
  156.  
  157.  
  158. endmodule
  159.  
  160. module video_palframe_mk3bit
  161. (
  162.         input  wire       plus1,
  163.  
  164.         input  wire [2:0] color_in,
  165.         output reg  [1:0] color_out
  166. );
  167.  
  168.         always @*
  169.         case( color_in )
  170.                 3'b000:  color_out <= 2'b00;
  171.                 3'b001:  color_out <= plus1 ? 2'b01 : 2'b00;
  172.                 3'b010:  color_out <= 2'b01;
  173.                 3'b011:  color_out <= plus1 ? 2'b10 : 2'b01;
  174.                 3'b100:  color_out <= 2'b10;
  175.                 3'b101:  color_out <= plus1 ? 2'b11 : 2'b10;
  176.                 default: color_out <= 2'b11;
  177.         endcase
  178.  
  179. endmodule
  180.  
  181.