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[/] [socgen/] [trunk/] [Projects/] [opencores.org/] [logic/] [ip/] [vga_char_ctrl/] [rtl/] [verilog/] [char_gen] - Blame information for rev 134

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Line No. Rev Author Line
1 131 jt_eaton 
 
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module `VARIANT`CHAR_GEN
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(
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input wire           clk,
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input wire           reset,
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input wire [13:0]    char_write_addr,
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input wire [7:0]     char_write_data,
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input wire           char_write_enable,
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input wire [13:0]    char_read_addr,               // character address "0" is upper left character
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input wire [2:0]     subchar_line,               // line number within 8 line block
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input wire [2:0]     subchar_pixel,               // pixel position within 8 pixel block
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input wire [7:0]     ascii_code,
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18 134 jt_eaton 
input wire [7:0]            char_gen_rom_data,
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output reg           pixel_on
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                         );
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reg                   latch_data;
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reg                   latch_low_data;
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reg                   shift_high;
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reg                   shift_low;
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reg [3:0]             latched_low_char_data;
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reg [7:0]             latched_char_data;
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// LATCH THE CHARTACTER DATA FROM THE CHAR GEN ROM AND CREATE A SERIAL CHAR DATA STREAM
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always @ (posedge clk )begin
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               if (reset) begin
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                    latch_data <= 1'b0;
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                    end
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               else if (subchar_pixel == 3'b110) begin
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                    latch_data <= 1'b1;
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                    end
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               else if (subchar_pixel == 3'b111) begin
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                    latch_data <= 1'b0;
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                    end
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               end
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always @ (posedge clk )begin
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               if (reset) begin
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                    latch_low_data <= 1'b0;
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                    end
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               else if (subchar_pixel == 3'b010) begin
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                    latch_low_data <= 1'b1;
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                    end
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               else if (subchar_pixel == 3'b011) begin
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                    latch_low_data <= 1'b0;
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                    end
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               end
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always @ (posedge clk )begin
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               if (reset) begin
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                    shift_high <= 1'b1;
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                    end
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               else if (subchar_pixel == 3'b011) begin
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                    shift_high <= 1'b0;
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                    end
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               else if (subchar_pixel == 3'b111) begin
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                    shift_high <= 1'b1;
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                    end
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               end
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always @ (posedge clk )begin
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               if (reset) begin
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                    shift_low <= 1'b0;
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                    end
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               else if (subchar_pixel == 3'b011) begin
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                    shift_low <= 1'b1;
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                    end
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               else if (subchar_pixel == 3'b111) begin
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                    shift_low <= 1'b0;
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                    end
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               end
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// serialize the CHARACTER MODE data
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always @ (posedge clk ) begin
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     if (reset)
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           begin
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               pixel_on              <= 1'b0;
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               latched_low_char_data <= 4'h0;
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               latched_char_data     <= 8'h00;
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          end
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     else if (shift_high)
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          begin
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               pixel_on              <= latched_char_data [7];
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               latched_char_data [7] <= latched_char_data [6];
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               latched_char_data [6] <= latched_char_data [5];
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               latched_char_data [5] <= latched_char_data [4];
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               latched_char_data [4] <= latched_char_data [7];
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                    if(latch_low_data) begin
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                         latched_low_char_data [3:0] <= latched_char_data [3:0];
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                         end
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                    else begin
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                         latched_low_char_data [3:0] <= latched_low_char_data [3:0];
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                         end
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               end
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     else if (shift_low)
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          begin
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               pixel_on                  <= latched_low_char_data [3];
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               latched_low_char_data [3] <= latched_low_char_data [2];
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               latched_low_char_data [2] <= latched_low_char_data [1];
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               latched_low_char_data [1] <= latched_low_char_data [0];
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               latched_low_char_data [0] <= latched_low_char_data [3];
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               if  (latch_data)   latched_char_data [7:0] <= char_gen_rom_data[7:0];
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               else               latched_char_data [7:0] <= latched_char_data [7:0];
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          end
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      else
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          begin
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          latched_low_char_data [3:0]  <= latched_low_char_data [3:0];
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          latched_char_data [7:0]      <= latched_char_data [7:0];
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          pixel_on                     <= pixel_on;
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          end
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     end
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endmodule //CHAR_GEN
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