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130 lines
2.9 KiB
Verilog
130 lines
2.9 KiB
Verilog
module PIXEL_GEN(
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// control
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reset,
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pixel_code,
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graph_pixel,
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pixel_clock,
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pixel_8p_2bit, // 64x64x4
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pixel_4p_2bit, // 128x64x4 128x96x4 128x192x4
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pixel_4p_1bit, // 128x64x2 128x96x2 128x192x2
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pixel_2p_1bit // 256x192x2
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);
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input reset;
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input [7:0] pixel_code;
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input [8:0] graph_pixel; // pixel number on the current line
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input pixel_clock;
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output reg [1:0] pixel_8p_2bit;
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output reg [1:0] pixel_4p_2bit;
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output reg pixel_4p_1bit;
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output reg pixel_2p_1bit;
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reg [7:0] latched_8p_2bit_data;
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reg [7:0] latched_4p_2bit_data;
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reg [7:0] latched_4p_1bit_data;
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reg [7:0] latched_2p_1bit_data;
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// 移位寄存器有四种模式
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// 每2个点 移 1 位
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// 每4个点 移 2 位
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// 每4个点 移 1 位
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// 每8个点 移 2 位
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// serialize the GRAPH MODE data
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always @ (posedge pixel_clock or posedge reset) begin
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if (reset)
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begin
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pixel_8p_2bit <= 2'b00;
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latched_8p_2bit_data <= 8'h00;
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end
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else begin
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case(graph_pixel[4:0])
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5'b00101:
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latched_8p_2bit_data[7:0] <= pixel_code;
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default:
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if(graph_pixel[3:0]==3'b110)
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{pixel_8p_2bit,latched_8p_2bit_data[7:2]} <= latched_8p_2bit_data[7:0];
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endcase
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end
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end
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// 延时：图形模式 128x64 4色
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// 1、(001)锁存 vram 地址，2、(010)读取 vram 3、(011)锁存 vram 数据 4、(100)空 5、(101)数据锁存至移位寄存器
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// 6、(110)移位得到点阵 7、(111)建立调色板，锁存色彩
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// serialize the GRAPH MODE data
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always @ (posedge pixel_clock or posedge reset) begin
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if (reset)
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begin
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pixel_4p_2bit <= 2'b00;
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latched_4p_2bit_data <= 8'h00;
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end
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else begin
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case(graph_pixel[3:0])
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4'b0101:
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latched_4p_2bit_data[7:0] <= pixel_code;
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default:
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if(graph_pixel[1:0]==2'b10)
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{pixel_4p_2bit,latched_4p_2bit_data[7:2]} <= latched_4p_2bit_data[7:0];
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endcase
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end
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end
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// serialize the GRAPH MODE data
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always @ (posedge pixel_clock or posedge reset) begin
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if (reset)
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begin
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pixel_4p_1bit <= 2'b00;
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latched_4p_1bit_data <= 8'h00;
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end
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else begin
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case(graph_pixel[4:0])
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5'b00101:
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latched_4p_1bit_data[7:0] <= pixel_code;
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default:
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if(graph_pixel[1:0]==2'b10)
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{pixel_4p_1bit,latched_4p_1bit_data[7:1]} <= latched_4p_1bit_data[7:0];
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endcase
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end
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end
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// 延时：图形模式 256x192 2色
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// 1、(001)锁存 vram 地址，2、(010)读取 vram 3、(011)锁存 vram 数据 4、(100)空 5、(101)数据锁存至移位寄存器
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// 6、(110)移位得到点阵 7、(111)建立调色板，锁存色彩
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// serialize the GRAPH MODE data
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always @ (posedge pixel_clock or posedge reset) begin
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if (reset)
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begin
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pixel_2p_1bit <= 1'b0;
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latched_2p_1bit_data <= 8'h00;
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end
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else begin
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case(graph_pixel[3:0])
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4'b0101:
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latched_2p_1bit_data[7:0] <= pixel_code;
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default:
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if(graph_pixel[0]==1'b0)
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{pixel_2p_1bit,latched_2p_1bit_data[7:1]} <= latched_2p_1bit_data[7:0];
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endcase
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end
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end
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endmodule //PIXEL_GEN
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