116 lines
3.4 KiB
Systemverilog
116 lines
3.4 KiB
Systemverilog
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module yayacemu (
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input wire clk_in,
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input int pc_in,
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output int pc_out
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);
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import "DPI-C" function void init_screen();
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wire [31:0] vram [0:2047];
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bit [7:0] memory [0:4095];
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wire [7:0] registers [0:15];
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logic [7:0] index_reg;
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logic rom_ready;
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int pc;
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rom_loader rl (memory, rom_ready);
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chip8_cpu cpu (memory, clk_in, vram, index_reg, registers, pc_in, pc_out);
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chip8_gpu gpu (vram);
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initial begin
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init_screen();
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end
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endmodule
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module chip8_cpu(
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input bit [7:0] memory [0:4095],
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input wire clk_in,
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output wire [31:0] vram [0:2047],
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output wire [7:0] index_reg,
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output wire [7:0] registers [0:15],
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input int pc_in,
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output int pc_out
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);
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logic [15:0] opcode;
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logic [15:0] scratch;
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logic [31:0] x_cord;
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logic [31:0] y_cord;
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logic [7:0] size;
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logic [31:0] screen_pixel;
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logic [7:0] sprite_pixel;
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int i;
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int r;
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int c;
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always_ff @(posedge clk_in) begin
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opcode = {memory[pc_in], memory[pc_in+1]};
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$display("HW : opcode is 0x%h (%b)", opcode, opcode);
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$display("HW : PC %0d", pc_in);
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casez(opcode)
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'h00E0: begin
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$display("HW : INSTR CLS");
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for(i = 0; i < 2048; i++) begin
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vram[i] = 0;
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end
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end
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'h00EE: $display("HW : INSTR RET");
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'h0???: $display("HW : INSTR SYS addr");
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'h1???: $display("HW : INSTR JP addr");
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'h2???: $display("HW : INSTR CALL addr");
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'h6???: begin
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$display("HW : INSTR LD Vx, byte");
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scratch = (opcode & 'h00FF);
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registers[(opcode & 'h0F00) >> 8] = scratch[7:0];
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end
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'h7???: begin
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$display("HW : INSTR ADD Vx, byte");
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scratch = (opcode & 'h00FF);
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registers[(opcode & 'h0F00) >> 8] += scratch[7:0];
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end
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'hA???: begin
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$display("HW : INSTR LD I, addr");
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scratch = (opcode & 'h0FFF);
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index_reg = scratch[7:0];
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end
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'hD???: begin
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$display("HW : INSTR DRW Vx, Vy, nibble");
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x_cord = {24'h000000, registers[(opcode & 'h0F00) >> 8]};
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y_cord = {24'h000000, registers[(opcode & 'h00F0) >> 4]};
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scratch = (opcode & 'h000F);
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size = scratch[7:0];
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for (r = 0; r < size; r++) begin
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for ( c = 0; c < 8; c++) begin
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screen_pixel = vram[((r + y_cord) * 64) + (x_cord + c)];
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sprite_pixel = memory[{24'h000000, index_reg} + r] & ('h80 >> c);
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if (|sprite_pixel) begin
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if (screen_pixel == 32'hFFFFFFFF) begin
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registers[15] = 1;
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end
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vram[((r + y_cord) * 64) + (x_cord + c)] = screen_pixel ^ 32'hFFFFFFFF;
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end
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end
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end
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end
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default: $display("HW : ILLEGAL INSTRUCTION");
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endcase
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pc_out <= pc_in + 2;
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end
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endmodule
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module chip8_gpu (
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input wire [31:0] vram [0:2047]
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);
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import "DPI-C" function void draw_screen(logic [31:0] vram [0:2047]);
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always_comb begin
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draw_screen(vram);
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end
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endmodule
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