Verilator-driven SDL simulation.

Author: nand2mario

loader/Makefile

@@ -1,8 +1,9 @@
 
 OBJ := nes_loader.o osd.o util.o
 
+# Link libstdc++ statically: https://web.archive.org/web/20160313071116/http://www.trilithium.com/johan/2005/06/static-libstdc/
 loader: $(OBJ)
-	g++ -o loader $(OBJ)
+	g++ -static-libgcc -static-libstdc++ -o loader $(OBJ)
 
 %.o: %.cpp
 	g++ -std=c++17 -c $< -o $@

src/cpu.v

@@ -242,9 +242,9 @@ end
 // Program counter
 ProgramCounter pc(clk, ce, LoadPC, GotInterrupt, DIN, T, PC, JumpNoOverflow);
 
-always @(posedge clk) if (!reset && ce && (PC == 'hc071 || PC == 'hc072)) begin
-    $write("pc=c071/c072");
-end
+// always @(posedge clk) if (!reset && ce && (PC == 'hc071 || PC == 'hc072)) begin
+//     $write("pc=c071/c072");
+// end
 
 reg IsNMIInterrupt = 0;
 reg LastNMI = 0;

src/hw_uart.v

@@ -17,6 +17,8 @@
 // Example: 10 MHz Clock, 115200 baud UART
 // (10000000)/(115200) = 87
 
+typedef logic [7:0] BYTE;
+
 module uart_rx 
   #(parameter CLKS_PER_BIT)
   (
@@ -71,7 +73,7 @@ module uart_rx
         // Check middle of start bit to make sure it's still low
         s_RX_START_BIT :
           begin
-            if (r_Clock_Count == (CLKS_PER_BIT-1)/2)
+            if (r_Clock_Count == BYTE'((CLKS_PER_BIT-1)/2))
               begin
                 if (r_Rx_Data == 1'b0)
                   begin
@@ -92,7 +94,7 @@ module uart_rx
         // Wait CLKS_PER_BIT-1 clock cycles to sample serial data
         s_RX_DATA_BITS :
           begin
-            if (r_Clock_Count < CLKS_PER_BIT-1)
+            if (r_Clock_Count < BYTE'(CLKS_PER_BIT-1))
               begin
                 r_Clock_Count <= r_Clock_Count + 1;
                 r_SM_Main     <= s_RX_DATA_BITS;
@@ -121,7 +123,7 @@ module uart_rx
         s_RX_STOP_BIT :
           begin
             // Wait CLKS_PER_BIT-1 clock cycles for Stop bit to finish
-            if (r_Clock_Count < CLKS_PER_BIT-1)
+            if (r_Clock_Count < BYTE'(CLKS_PER_BIT-1))
               begin
                 r_Clock_Count <= r_Clock_Count + 1;
                 r_SM_Main     <= s_RX_STOP_BIT;

src/memory_controller.v

@@ -72,7 +72,7 @@ wire [15:0] MemDout;
 reg [2:0] cycles;
 reg r_read_a, r_read_b;
 wire MemBusy, MemDataReady;
-wire fail_high, fail_low, tester_rd, tester_wr, tester_refresh, testing;
+wire tester_rd, tester_wr, tester_refresh;
 wire [25:0] tester_addr;
 wire [15:0] tester_din;
 

src/mmu.v

@@ -447,8 +447,8 @@ module MMC5(input clk, input ce, input reset,
   always @(posedge clk) begin
     if (ce) begin
       if (prg_write && prg_ain[15:10] == 6'b010100) begin // $5000-$53FF
-        if (prg_ain <= 16'h5113)
-          $write("%X <= %X (%d)\n", prg_ain, prg_din, ppu_scanline);
+        // if (prg_ain <= 16'h5113)
+        //   $write("%X <= %X (%d)\n", prg_ain, prg_din, ppu_scanline);
         casez(prg_ain[9:0])
         10'h100: prg_mode <= prg_din[1:0];
         10'h101: chr_mode <= prg_din[1:0];
@@ -1329,7 +1329,7 @@ module Mapper71(input clk, input ce, input reset,
     ciram_select <= 0;
   end else if (ce) begin
     if (prg_ain[15] && prg_write) begin
-      $write("%X <= %X (bank = %x)\n", prg_ain, prg_din, prg_bank);
+      // $write("%X <= %X (bank = %x)\n", prg_ain, prg_din, prg_bank);
       if (!prg_ain[14] && mapper232) // $8000-$BFFF Outer bank select (only on iNES 232)
         prg_bank[3:2] <= prg_din[4:3];
       if (prg_ain[14:13] == 0)       // $8000-$9FFF Fire Hawk Mirroring

src/nes.v

@@ -123,7 +123,7 @@ endmodule
 module NES(input clk, input reset, input ce,
            input [31:0] mapper_flags,
            output [15:0] sample, // sample generated from APU
-           output [5:0] color,  // pixel generated from PPU
+           output [5:0] color /*verilator public*/,  // pixel generated from PPU
            output joypad_strobe,// Set to 1 to strobe joypads. Then set to zero to keep the value.
            output [1:0] joypad_clock, // Set to 1 for each joypad to clock it.
            input [1:0] joypad_data, // Data for each joypad.
@@ -139,8 +139,8 @@ module NES(input clk, input reset, input ce,
            output memory_write,         // is a write operation
            output [7:0] memory_dout,
 
-           output [8:0] cycle,
-           output [8:0] scanline
+           output [8:0] cycle /*verilator public*/,
+           output [8:0] scanline /*verilator public*/
 
 //           output reg [31:0] dbgadr,
 //           output [1:0] dbgctr

src/nes_tang20k.v

@@ -3,7 +3,7 @@
 // nand2mario, 2022.9
 //
 
-`timescale 1ns / 100ps
+// `timescale 1ns / 100ps
 
 // Main clock frequency
 localparam FREQ=32_250_000;
@@ -126,10 +126,12 @@ module NES_Tang20k(
   wire [7:0] uart_addr;
   wire       uart_write;
   wire       uart_error;
+`ifndef VERILATOR
   UartDemux  
         #(.FREQ(FREQ), .BAUDRATE(BAUDRATE)) 
         uart_demux(clk, 1'b0, UART_RXD, uart_data, uart_addr, uart_write, uart_error);
 //        uart_demux(clk, ~sys_resetn, UART_RXD, uart_data, uart_addr, uart_write, uart_error);
+`endif
 
   // ROM loader
   reg  [7:0] loader_conf;       // bit 0 is reset
@@ -200,7 +202,7 @@ module NES_Tang20k(
         .clk(clk), .reset(loader_reset), .indata(loader_input), .indata_clk(loader_clk),
         .mem_addr(loader_addr), .mem_data(loader_write_data), .mem_write(loader_write),
         .mem_refresh(loader_refresh), .mapper_flags(mapper_flags), 
-        .done(loader_done), .error(loader_fail));
+        .done(loader_done), .error(loader_fail), .loader_state(), .loader_bytes_left());
 
   // The NES machine
   // nes_ce  / 0 \___/ 1 \___/ 2 \___/ 3 \___/ 4 \___/ 5 \___/ 0 \___/
@@ -283,6 +285,7 @@ module NES_Tang20k(
   wire [1:0] rclkpos;
   wire [2:0] rclksel;
   wire [3:0] test_state;
+  wire write_level_done, read_calib_done, ram_testing, fail_high, fail_low;
   MemoryController memory(.clk(clk), .pclk(pclk), .fclk(fclk), .ck(ck), .resetn(sys_resetn & nes_lock & mem_resetn),
         .read_a(memory_read_cpu && run_mem), 
         .read_b(memory_read_ppu && run_mem),
@@ -506,15 +509,23 @@ endmodule
 
 
 `ifdef EMBED_GAME
-// zf: Feed INES data to Game_Loader
+// Feed INES data to Game_Loader
 module GameData (input clk, input reset, input start,
     output reg [7:0] odata, output reg odata_clk
     );
 
-    // 24KB+ buffer for ROM
-    reg [7:0] INES[24719:0];
-    reg [21:0] INES_SIZE = 24719; 
-    initial $readmemh("BattleCity.nes.hex", INES);
+    // localparam [21:0] INES_SIZE = 24719; 
+    // localparam string INES_FILE="../BattleCity.nes.hex";
+
+    // localparam [21:0] INES_SIZE = 131088; 
+    // localparam string INES_FILE="../Contra.nes.hex";
+
+    localparam [21:0] INES_SIZE = 262160; 
+    localparam string INES_FILE="../SuperC.nes.hex";
+
+    // Buffer for ROM file
+    reg [7:0] INES[INES_SIZE:0];
+    initial $readmemh(INES_FILE, INES);
 
     reg [1:0] state = 0;
     reg [21:0] addr = 0;
@@ -525,22 +536,27 @@ module GameData (input clk, input reset, input start,
             state <= 0;
             addr <= 0;  // odata gets INES[0]
             odata_clk <= 0;
-        end else if (start && state == 0) begin
+        end else if (start && state == 2'd0) begin
             // start loading
             state <= 1;
-        end else if (state==1) begin
+        end else if (state == 2'd1) begin
             if (addr == INES_SIZE) begin
                 // we've just sent the last byte
-                state <= 2;     // end of data
+                state <= 2'd3;     // end of data
                 odata_clk <= 0;
             end else begin
                 // pump data to Game_Loader
 /* verilator lint_off WIDTH */
                 odata <= INES[addr];
 /* verilator lint_on WIDTH */
                 odata_clk <= 1;
-                addr <= addr + 1;
+                state <= 2;   
             end
+        end else if (state == 2'd2) begin
+          // wait one clock cycle, then send next byte
+          odata_clk <= 0;
+          addr <= addr + 1;
+          state <= 1;
         end
     end
 endmodule

verilator/Makefile

@@ -1,13 +1,20 @@
 
-.PHONY: build sim verilate
-	
+CFLAGS_SDL=$(shell sdl2-config --cflags) -O3
+LIBS_SDL=$(shell sdl2-config --libs)
 
+.PHONY: build sim verilate clean
+	
 build: ./obj_dir/VNES_Tang20k
 
-verilate: sim_main.cpp hdl/*.v
+verilate: ./obj_dir/VNES_Tang20k.cpp
+
+./obj_dir/VNES_Tang20k.cpp: sim_main.cpp hdl/*.v
 	@echo
 	@echo "### VERILATE ####"
-	verilator --top-module NES_Tang20k --trace -cc hdl/*.v --exe sim_main.cpp
+	mkdir -p obj_dir
+	cd obj_dir; ln -sf ../game.nes.hex .; ln -sf ../hdl/src/*.txt .
+	# verilator --top-module NES_Tang20k --trace -cc -O3 -CFLAGS "$(CFLAGS_SDL)" -LDFLAGS "$(LIBS_SDL)" hdl/*.v --exe sim_main.cpp
+	verilator --top-module NES_Tang20k -cc -O3 --exe -CFLAGS "$(CFLAGS_SDL)" -LDFLAGS "$(LIBS_SDL)" hdl/*.v sim_main.cpp
 
 ./obj_dir/VNES_Tang20k: verilate
 	@echo
@@ -17,5 +24,7 @@ verilate: sim_main.cpp hdl/*.v
 sim: ./obj_dir/VNES_Tang20k
 	@echo
 	@echo "### SIMULATION ###"
-	@echo "This will take some time..."
 	@cd obj_dir && ./VNES_Tang20k
+
+clean:
+	rm -rf obj_dir

verilator/README

@@ -0,0 +1,22 @@
+This is a Verilator-driven graphical simulation of nestang. Should be useful in debugging game / mapper support, among other things.
+
+To run the simulation:
+
+```
+./setup.sh `pwd`/..
+hexdump -ve '1/1 "%02x\n"' game.nes > game.nes.hex
+# change INES_SIZE in nes_tang20k.v to reflect size of game.nes
+make sim
+```
+
+You need to set up verilator / libsdl2 with something like:
+
+```
+# Linux
+sudo apt install verilator libsdl2-dev
+
+# Mac
+brew install verilator sdl2
+```
+
+For an overview of verilator, see: https://www.itsembedded.com/dhd/verilator_2/

verilator/README.md

@@ -0,0 +1,12 @@
+#pragma once
+
+const unsigned NES_PALETTE[64] = {
+    0x545454,  0x001e74,  0x081090,  0x300088,  0x440064,  0x5c0030,  0x540400,  0x3c1800,
+    0x202a00,  0x083a00,  0x004000,  0x003c00,  0x00323c,  0x000000,  0x000000,  0x000000,
+    0x989698,  0x084cc4,  0x3032ec,  0x5c1ee4,  0x8814b0,  0xa01464,  0x982220,  0x783c00,
+    0x545a00,  0x287200,  0x087c00,  0x007628,  0x006678,  0x000000,  0x000000,  0x000000,
+    0xeceeec,  0x4c9aec,  0x787cec,  0xb062ec,  0xe454ec,  0xec58b4,  0xec6a64,  0xd48820,
+    0xa0aa00,  0x74c400,  0x4cd020,  0x38cc6c,  0x38b4cc,  0x3c3c3c,  0x000000,  0x000000,
+    0xeceeec,  0xa8ccec,  0xbcbcec,  0xd4b2ec,  0xecaeec,  0xecaed4,  0xecb4b0,  0xe4c490,
+    0xccd278,  0xb4de78,  0xa8e290,  0x98e2b4,  0xa0d6e4,  0xa0a2a0,  0x000000,  0x000000,
+};

verilator/nes_palette.h

@@ -11,21 +11,22 @@ fi
 DIR=$1
 
 mkdir -p hdl
-ln -s $DIR/src/apu.v hdl
-ln -s $DIR/src/compat.v hdl
-ln -s $DIR/src/cpu.v hdl
-ln -s $DIR/src/hw_sound.v hdl
-ln -s $DIR/src/hw_uart.v hdl
-ln -s $DIR/src/MicroCode.v hdl
-ln -s $DIR/src/mmu.v hdl
-ln -s $DIR/src/nes_tang20k.v hdl
-ln -s $DIR/src/nes.v hdl
-ln -s $DIR/src/ppu.v hdl
-ln -s $DIR/src/sdram.v hdl
+ln -sf $DIR/src/apu.v hdl
+ln -sf $DIR/src/compat.v hdl
+ln -sf $DIR/src/cpu.v hdl
+ln -sf $DIR/src/hw_sound.v hdl
+ln -sf $DIR/src/MicroCode.v hdl
+ln -sf $DIR/src/mmu.v hdl
+ln -sf $DIR/src/nes_tang20k.v hdl
+ln -sf $DIR/src/nes.v hdl
+ln -sf $DIR/src/ppu.v hdl
+ln -sf $DIR/src/memory_controller.v hdl
+ln -sf $DIR/src/game_loader.v hdl
+ln -sf $DIR/src hdl/src
 
-mkdir -p obj_dir
-ln -s $DIR/src/oam_palette.txt obj_dir
-ln -s $DIR/src/*.hex obj_dir
+echo "hdl/ directory setup done."
 
-
-echo "Setup done."
+if [ ! -f game.nes.hex ]; then
+    echo "You need game.nes.hex ROM file to do simulation. To generate from .nes files: "
+    echo '  hexdump -ve '"'"'1/1 "%02x\\n'"'"' game.nes > game.nes.hex'
+fi