第18课: NES PPU基础

// 第18课: NES PPU基础 module nes_ppu_basics ( input wire clk, input wire rst_n, output reg hsync, output reg vsync, output reg [7:0] pixel_r, pixel_g, pixel_b, output reg pixel_valid, output reg [8:0] scan_x, output reg [7:0] scan_y, output reg frame_done ); localparam H_VISIBLE=256, V_VISIBLE=240, H_TOTAL=341, V_TOTAL=262; localparam H_SYNC_START=257, V_SYNC_START=241; reg [1:0] frame_buf [0:255][0:239]; integer x,y; reg [23:0] palette [0:3]; initial begin palette[0]=24'h000000;palette[1]=24'h555555;palette[2]=24'hAAAAAA;palette[3]=24'hFFFFFF; for(y=0;y<240;y=y+1) for(x=0;x<256;x=x+1) frame_buf[x][y]=((x/16+y/16)%2==0)?2'd3:2'd0; end always @(posedge clk or negedge rst_n) begin if(!rst_n) begin hsync<=0;vsync<=0;pixel_r<=0;pixel_g<=0;pixel_b<=0;pixel_valid<=0;scan_x<=0;scan_y<=0;frame_done<=0; end else begin frame_done<=0; if(scan_x<H_TOTAL-1) scan_x<=scan_x+1; else begin scan_x<=0; if(scan_y<V_TOTAL-1) scan_y<=scan_y+1; else begin scan_y<=0;frame_done<=1;end end hsync<=(scan_x>=H_SYNC_START); vsync<=(scan_y>=V_SYNC_START&&scan_y<V_SYNC_START+3); if(scan_x<H_VISIBLE&&scan_y<V_VISIBLE) begin pixel_valid<=1; pixel_r<=palette[frame_buf[scan_x][scan_y]][23:16];pixel_g<=palette[frame_buf[scan_x][scan_y]][15:8];pixel_b<=palette[frame_buf[scan_x][scan_y]][7:0]; end else begin pixel_valid<=0;pixel_r<=0;pixel_g<=0;pixel_b<=0; end end end endmodule

/* verilator lint_off WIDTHEXPAND */ /* verilator lint_off WIDTHTRUNC */ /* verilator lint_off UNOPTFLAT */ module tb; reg clk,rst_n; wire hsync,vsync,pixel_valid,frame_done; wire [7:0] pixel_r,pixel_g,pixel_b; wire [8:0] scan_x; wire [7:0] scan_y; nes_ppu_basics uut (.clk(clk),.rst_n(rst_n),.hsync(hsync),.vsync(vsync),.pixel_r(pixel_r),.pixel_g(pixel_g),.pixel_b(pixel_b),.pixel_valid(pixel_valid),.scan_x(scan_x),.scan_y(scan_y),.frame_done(frame_done)); always clk = #10 ~clk; initial begin $dumpfile("ppu.vcd");$dumpvars(0,tb);clk=0;rst_n=0;repeat(5)@(posedge clk);rst_n=1; $display("=== NES PPU基础仿真 ===");$display("256x240帧缓冲正确");$display(""); $display("--- PPU时序参数 ---");$display(" 分辨率: 256x240");$display(" 水平总像素: 341");$display(" 垂直总行数: 262");$display(" H同步起始: 像素257");$display(" V同步起始: 行241");$display(""); $display("--- 帧缓冲检查 ---");$display(" 总像素: 256x240 = %0d",256*240); begin integer cx,cy,white_count=0,black_count=0; for(cy=0;cy<240;cy=cy+1) for(cx=0;cx<256;cx=cx+1) if(uut.frame_buf[cx][cy]==2'd3) white_count=white_count+1; else black_count=black_count+1; $display(" 白色像素: %0d",white_count);$display(" 黑色像素: %0d",black_count); if(white_count+black_count==256*240) $display(" ✅ 256x240帧缓冲大小正确"); if(white_count>0&&black_count>0) $display(" ✅ 棋盘格模式正确(有黑有白)"); end repeat(20)@(posedge clk);$display(" scan_x=%0d scan_y=%0d pixel_valid=%0d",scan_x,scan_y,pixel_valid); if(pixel_valid) $display(" ✅ PPU输出有效像素"); $display("");$display("--- 画面预览(16x12 缩略) ---"); begin integer py,px;for(py=0;py<12;py=py+1) begin $write(" ");for(px=0;px<16;px=px+1) if(uut.frame_buf[px*16][py*20]==2'd3) $write("██");else $write(" ");$write("\n");end end $display("");$display("✅ 256x240帧缓冲正确验证通过!");$display("🏆 成就解锁: 256x240帧缓冲正确!");$finish; end endmodule

# 编译 verilator --cc *.sv --exe sim_main.cpp --top-module tb --timing --trace \ --build -j 4 -o sim \ -Wno-WIDTHEXPAND -Wno-WIDTHTRUNC -Wno-UNOPTFLAT \ -Wno-TIMESCALEMOD -Wno-STMTDLY -Wno-WIDTH \ -Wno-UNSIGNED -Wno-SELRANGE -Wno-BLKSEQ # 运行 ./obj_dir/sim # 查看波形(可选) gtkwave sim.vcd