rng module

chip8.sv

@@ -35,6 +35,15 @@ logic debug_overlay;
       rd_memory_data
   );
 
+  logic [7:0] random_byte;
+  rng randy(
+      slow_clk,
+      {wr_memory_data, rd_memory_data},
+      keymap,
+      cycle_counter,
+      random_byte
+      );
+
   logic [15:0] keymap;
 
   keypad keypad (
@@ -58,6 +67,7 @@ logic debug_overlay;
       fpga_clk,
       rd_memory_data,
       keymap,
+      random_byte,
       cycle_counter,
       rd_memory_address,
       wr_memory_address,

cpu.sv

@@ -5,6 +5,7 @@ module cpu (
     input wire fpga_clk,
     input wire [7:0] rd_memory_data,
     input wire [15:0] keymap,
+    input wire [7:0] random_byte,
     output int cycle_counter,
     output logic [11:0] rd_memory_address,
     output logic [11:0] wr_memory_address,
@@ -109,7 +110,7 @@ logic [5:0] lcd_led;
   typedef enum {INIT, DRAW} draw_stage;
   
   typedef enum {CLS, LD, DRW, JP, ALU, CALU, CALL, RET, ALUJ, LDL, BCD, IOJ, IOW, NIOJ} cpu_opcode;
-  typedef enum {REG, IDX_REG, BYTE, MEM, SPRITE_MEM, KEY, DELAY_TIMER, SOUND_TIMER} data_type;
+  typedef enum {REG, IDX_REG, BYTE, MEM, SPRITE_MEM, KEY, DELAY_TIMER, SOUND_TIMER, RAND} data_type;
 
   struct {
       draw_stage stage;
@@ -161,7 +162,6 @@ logic [5:0] lcd_led;
   end
 
   always_ff @(posedge clk_in) begin
-      $display("%0d", sound_timer);
     if (cycle_counter % 200 == 0) begin
         vblank <= 0; 
         if (delay_timer > 0)
@@ -423,6 +423,17 @@ logic [5:0] lcd_led;
                     compute_of <= 0;
                     state <= ST_EXEC; 
                 end
+                16'hC???: begin
+                    instr.op <= LD; 
+
+                    instr.src <= RAND;
+                    instr.src_byte <= {4'h0, opcode[7:0]};
+
+                    instr.dst <= REG;
+                    instr.dst_reg <= opcode[11:8];
+
+                    state <= ST_EXEC; 
+                end
                 16'hD???: begin
                    instr.op <= DRW; 
 
@@ -641,6 +652,9 @@ logic [5:0] lcd_led;
                     end else if (instr.src == DELAY_TIMER) begin
                         instr.src_byte <= { 4'h0, delay_timer };
                         instr.src <= BYTE;
+                    end else if (instr.src == RAND) begin
+                        instr.src_byte <= {4'h0, random_byte} & instr.src_byte ;
+                        instr.src <= BYTE;
                     end
                 end
                 LDL: begin

makefile

@@ -2,7 +2,7 @@
 
 SDL_CFLAGS = `sdl2-config --cflags`
 SDL_LDFLAGS = `sdl2-config --libs`
-SV_FILES=aastructs.sv cpu.sv chip8.sv gpu.sv alu.sv keypad.sv
+SV_FILES=aastructs.sv cpu.sv chip8.sv gpu.sv alu.sv keypad.sv rng.sv
 
 lint:
 	verilator --lint-only -DDUMMY_GPU --timing ${SV_FILES} 

yayacemu.cpp

@@ -18,6 +18,9 @@ SDL_Window *window;
 SDL_Renderer *renderer;
 SDL_Texture *texture;
 
+int keys[16];
+bool is_beeping;
+
 void init_screen() {
   SDL_Init(SDL_INIT_EVERYTHING);
   window = SDL_CreateWindow(
@@ -30,7 +33,7 @@ void init_screen() {
                               SDL_TEXTUREACCESS_STREAMING, SCREEN_WIDTH,
                               SCREEN_HEIGHT);
 }
-bool is_beeping;
+
 void draw_screen(const svLogicVecVal *vram) {
   uint32_t *screen = (uint32_t *)malloc(SCREEN_WIDTH * SCREEN_HEIGHT * 32);
   for (int i = 0; i < 1024; i++) {
@@ -45,21 +48,12 @@ void draw_screen(const svLogicVecVal *vram) {
   SDL_RenderCopy(renderer, texture, NULL, NULL);
   SDL_RenderPresent(renderer);
   free(screen);
-  // std::cout << "INF_EMU: Drawing Frame" << '\n';
 }
 
-// 1 2 3 A
-// 4 5 6 B
-// 7 8 9 C
-// * 0 # D
-//
-int keys[16];
 uint8_t get_key(uint8_t col) {
   SDL_Event event;
   uint8_t res = 0xFF;
 
-  // col 1000 - r1
-
   while (SDL_PollEvent(&event)) {
     uint8_t down = 0;
     switch (event.type) {
@@ -178,10 +172,12 @@ uint8_t get_key(uint8_t col) {
     if (col == 0b1011)
       res = res & 0b0111;
   }
+
   if (keys[12] == 1) {
     if (col == 0b0111)
       res = res & 0b1110;
   }
+
   if (keys[13] == 1) {
     if (col == 0b0111)
       res = res & 0b1101;
@@ -191,13 +187,12 @@ uint8_t get_key(uint8_t col) {
     if (col == 0b0111)
       res = res & 0b1011;
   }
+
   if (keys[15] == 1) {
     if (col == 0b0111)
       res = res & 0b0111;
   }
 
-  //if (res != 0)
-  //  printf("%04b %04b\n", res, col);
   return res;
 }
 
@@ -214,11 +209,10 @@ int main(int argc, char **argv) {
     dut->fpga_clk ^= 1;
     dut->eval();
 
-
     is_beeping = dut->beep == 1;
 
     if (SDL_QuitRequested()) {
-      std::cout << "INF_EMU: Received Quit from SDL. Goodbye!" << '\n';
+      std::cout << "Goodbye!" << '\n';
       break;
     }
   }