graphics working

yayacemu.sv

@@ -0,0 +1,115 @@
+module yayacemu (
+    input wire clk_in,
+    input int pc_in,
+    output int pc_out
+    );
+    import "DPI-C" function void init_screen();
+
+    wire [31:0] vram [0:2047];
+    bit [7:0] memory [0:4095];
+    wire [7:0] registers [0:15];
+    logic [7:0] index_reg;
+    logic rom_ready;
+    int pc;
+
+    rom_loader rl (memory, rom_ready);
+    chip8_cpu cpu (memory, clk_in, vram, index_reg, registers, pc_in, pc_out);
+    chip8_gpu gpu (vram);
+
+    initial begin 
+        init_screen();
+    end
+
+endmodule
+
+module chip8_cpu(
+    input bit [7:0] memory [0:4095],
+    input wire clk_in,
+    output wire [31:0] vram [0:2047],
+    output wire [7:0] index_reg,
+    output wire [7:0] registers [0:15],
+    input int pc_in,
+    output int pc_out
+    );
+
+    logic [15:0] opcode;
+    logic [15:0] scratch;
+
+    logic [31:0] x_cord;
+    logic [31:0] y_cord;
+    logic [7:0] size;
+    logic [31:0] screen_pixel;
+    logic [7:0] sprite_pixel;
+
+    int i;
+
+    int r;
+    int c;
+    always_ff @(posedge clk_in) begin
+        opcode = {memory[pc_in],  memory[pc_in+1]};
+        $display("HW     : opcode is 0x%h (%b)", opcode, opcode);
+        $display("HW     : PC %0d", pc_in);
+
+        casez(opcode)
+            'h00E0: begin 
+                $display("HW     : INSTR CLS");
+                for(i = 0; i < 2048; i++) begin
+                    vram[i] = 0;
+                end
+            end
+            'h00EE: $display("HW     : INSTR RET");
+            'h0???: $display("HW     : INSTR SYS addr");
+            'h1???: $display("HW     : INSTR JP addr");
+            'h2???: $display("HW     : INSTR CALL addr");
+            'h6???: begin
+                $display("HW     : INSTR LD Vx, byte");
+                scratch = (opcode & 'h00FF);
+                registers[(opcode & 'h0F00) >> 8] = scratch[7:0];
+            end
+            'h7???: begin
+                $display("HW     : INSTR ADD Vx, byte");
+                scratch = (opcode & 'h00FF);
+                registers[(opcode & 'h0F00) >> 8] += scratch[7:0];
+            end
+            'hA???: begin
+                $display("HW     : INSTR LD I, addr");
+                scratch = (opcode & 'h0FFF);
+                index_reg = scratch[7:0];
+            end
+            'hD???: begin
+                $display("HW     : INSTR DRW Vx, Vy, nibble");
+                x_cord = {24'h000000, registers[(opcode & 'h0F00) >> 8]};
+                y_cord = {24'h000000, registers[(opcode & 'h00F0) >> 4]};
+
+                scratch = (opcode & 'h000F);
+                size = scratch[7:0];
+
+                for (r = 0; r < size; r++) begin 
+                    for ( c = 0; c < 8; c++) begin 
+                        screen_pixel = vram[((r + y_cord) * 64) + (x_cord + c)];
+                        sprite_pixel = memory[{24'h000000, index_reg} + r] & ('h80 >> c);
+
+                        if (|sprite_pixel) begin 
+                           if (screen_pixel == 32'hFFFFFFFF) begin 
+                                registers[15] = 1;
+                           end 
+                           vram[((r + y_cord) * 64) + (x_cord + c)] = screen_pixel ^ 32'hFFFFFFFF;
+                        end 
+                  end 
+                end 
+            end
+            default: $display("HW     : ILLEGAL INSTRUCTION");
+        endcase
+        
+        pc_out <= pc_in + 2;
+    end
+endmodule
+
+module chip8_gpu (
+    input wire [31:0] vram [0:2047]
+    );
+    import "DPI-C" function void draw_screen(logic [31:0] vram [0:2047]);
+    always_comb begin
+       draw_screen(vram); 
+    end
+endmodule