use 1 bit map for screen

.gitmodules

@@ -0,0 +1,3 @@
+[submodule "the-bomb"]
+	path = the-bomb
+	url = git@github.com:nickorlow/the-bomb.git

chip8.sv

@@ -3,7 +3,7 @@ module chip8 (
     input wire rst_in
 );
 
-  bit [31:0] vram[0:2047];
+  bit vram[0:2047];
   bit [7:0] memory[0:4095];
 
   bit keyboard[15:0];
@@ -12,12 +12,18 @@ module chip8 (
   bit [15:0] program_counter;
   int cycle_counter;
 
+  bit rom_ready;
+  bit font_ready;
+  bit system_ready;
+  bit halt;
+
   bit [7:0] random_number;
 
+  and(system_ready, rom_ready, font_ready);
 
   beeper beeper (sound_timer);
   cpu cpu (
-      rst_in,
+      system_ready,
       memory,
       clk_in,
       keyboard,
@@ -39,10 +45,10 @@ module chip8 (
       cycle_counter,
       random_number
   );
-  rom_loader loader (memory);
+  rom_loader loader (clk_in, rst_in, memory, rom_ready);
 
-  always_ff @(posedge clk_in) begin
-    if (rst_in) begin
+  always_ff @(negedge clk_in) begin
+    if (~font_ready) begin
         bit [7:0] fontset[79:0] = {
           8'hF0,
           8'h90,
@@ -131,10 +137,7 @@ module chip8 (
           memory[i] = fontset[79-i];
         end
 
-        // Initialize keyboard bits
-        for (int i = 0; i < 15; i++) begin
-          keyboard[i] = 0;
-        end
+        font_ready = 1;
     end
   end
 endmodule

cpu.sv

@@ -1,12 +1,12 @@
 module cpu (
-    input wire rst_in,
+    input wire system_ready,
     output bit [7:0] memory[0:4095],
     input wire clk_in,
     input wire keyboard[15:0],
     input wire [7:0] random_number,
     output int cycle_counter,
     output wire [15:0] program_counter,
-    output wire [31:0] vram[0:2047],
+    output wire vram[0:2047],
     output wire [7:0] sound_timer
 );
 
@@ -29,19 +29,11 @@ module cpu (
   logic [31:0] x_cord;
   logic [31:0] y_cord;
   logic [7:0] size;
-  logic [31:0] screen_pixel;
+  logic screen_pixel;
   logic [7:0] sprite_pixel;
 
-  always_ff @(posedge clk_in) begin
-    if (rst_in) begin
-        halt = 0;
-        watch_key = 255;
-        sound_timer = 0;
-        delay_timer = 0;
-        cycle_counter = 0;
-        program_counter = 'h200;
-        stack_pointer = 4'b0000;
-    end
+  always_ff @(negedge clk_in) begin
+    if (system_ready) begin
     opcode = {memory[program_counter+0], memory[program_counter+1]};
     $display("HW     : opcode is 0x%h (%b)", opcode, opcode);
     $display("HW     : PC %0d 0x%h", program_counter, program_counter);
@@ -199,10 +191,10 @@ module cpu (
               sprite_pixel = memory[{16'h0000, index_reg}+r] & ('h80 >> c);
 
               if (|sprite_pixel) begin
-                if (screen_pixel == 32'hFFFFFFFF) begin
+                if (screen_pixel == 1) begin
                   registers[15] = 1;
                 end
-                vram[((r+y_cord)*64)+(x_cord+c)] ^= 32'hFFFFFFFF;
+                vram[((r+y_cord)*64)+(x_cord+c)] ^= 1;
               end
             end
           end
@@ -295,4 +287,5 @@ module cpu (
 
     cycle_counter++;
 end
+  end
 endmodule

gpu.sv

@@ -1,9 +1,9 @@
 module gpu (
-    input wire [31:0] vram[0:2047]
+    input wire vram[0:2047]
 );
 
   import "DPI-C" function void init_screen();
-  import "DPI-C" function void draw_screen(logic [31:0] vram[0:2047]);
+  import "DPI-C" function void draw_screen(logic vram[0:2047]);
 
   initial begin
     init_screen();

keyboard.sv

@@ -5,7 +5,7 @@ module keyboard (
 
   import "DPI-C" function bit [7:0] get_key();
 
-  always_ff @(posedge clk_in) begin
+  always_ff @(negedge clk_in) begin
     bit [7:0] keyval = get_key();
     if (&keyval != 1) begin
       keyboard[keyval[3:0]] = keyval[7];

makefile

@@ -17,6 +17,3 @@ clean:
 
 format:
 	verible-verilog-format *.sv --inplace && clang-format *.cpp -i
-
-
-

rom_loader.sv

@@ -1,13 +1,22 @@
 module rom_loader (
-    output bit [7:0] memory[0:4095]
+    input wire clk_in,
+    input wire rst_in,
+    output bit [7:0] memory[0:4095],
+    output bit rom_ready
 );
 
   import "DPI-C" function int load_rom();
   import "DPI-C" function bit [7:0] get_next_instr();
   import "DPI-C" function void close_rom();
+  int rom_size;
 
-  initial begin
-    int rom_size = load_rom();
+  always @(negedge clk_in) begin
+    if (rst_in) begin
+        rom_ready = 0;
+    end
+
+    if (~rom_ready) begin
+        rom_size = load_rom();
         $display("HW     : ROM size is %0d bytes (%0d bits) (%0d instructions)", rom_size,
                  rom_size * 8, rom_size / 2);
         for (int i = 0; i < rom_size; i++) begin
@@ -15,5 +24,7 @@ module rom_loader (
         end
         close_rom();
         $display("HW     : ROM loaded successfully");
+        rom_ready = 1;
+    end
   end
 endmodule

the-bomb

@@ -0,0 +1 @@
+Subproject commit 69d8de45d344738425b88d9f8506a6c5c715a7ca

yayacemu.cpp

@@ -41,10 +41,10 @@ void set_beep(const svBit beep) {
     SDL_SetTextureColorMod(texture, 255, 255, 255);
 }
 
-void draw_screen(const svLogicVecVal *vram) {
+void draw_screen(const svLogic *vram) {
   uint32_t *screen = (uint32_t *)malloc(SCREEN_WIDTH * SCREEN_HEIGHT * 32);
   for (int i = 0; i < SCREEN_WIDTH * SCREEN_HEIGHT; i++) {
-    screen[i] = vram[i].aval;
+    screen[i] = vram[i] == 1 ? 0xFFFFFFFF : 0x00000000;
   }
   SDL_UpdateTexture(texture, NULL, screen, sizeof(screen[0]) * SCREEN_WIDTH);
   SDL_RenderClear(renderer);