GUI and CPU/PPU timing

CMakeLists.txt

@@ -13,6 +13,7 @@ add_subdirectory(mappers)
 add_subdirectory(rom)
 add_subdirectory(debugger)
 add_subdirectory(utils)
+add_subdirectory(gui)
 
 list(APPEND EXTRA_INCLUDES
         "${PROJECT_SOURCE_DIR}/cpu"
@@ -20,14 +21,15 @@ list(APPEND EXTRA_INCLUDES
         "${PROJECT_SOURCE_DIR}/mappers"
         "${PROJECT_SOURCE_DIR}/rom"
         "${PROJECT_SOURCE_DIR}/debugger"
-        "${PROJECT_SOURCE_DIR}/utils")
+        "${PROJECT_SOURCE_DIR}/utils"
+        "${PROJECT_SOURCE_DIR}/gui")
 
 set(HEADERS include/system.h include/types.h)
 set(SOURCE main.c system.c)
 
 add_executable(nes_emulator ${HEADERS} ${SOURCE})
 
-target_link_libraries(nes_emulator nes_cpu nes_ppu nes_mappers nes_rom nes_debugger nes_utils log.c)
+target_link_libraries(nes_emulator nes_cpu nes_ppu nes_mappers nes_rom nes_debugger nes_utils nes_gui log.c)
 target_include_directories(nes_emulator PUBLIC
         "${PROJECT_BINARY_DIR}"
         ${EXTRA_INCLUDES})

cpu/cpu.c

@@ -37,10 +37,11 @@ void cpu_init() {
     cpu_state.status = 0x04;
     cpu_state.oam_dma_triggered = false;
     cpu_state.nmi_requested = false;
+    cpu_state.busy_cycle_count = 0;
 }
 
 void print_registers(byte op, unsigned long cycle_count) {
-    log_info("%#02x %#02x %s \t A:%#02x X:%#02x Y:%#02x F:%#02x SP:%#02x \t [%d]",
+    log_debug("%#02x %#02x %s \t A:%#02x X:%#02x Y:%#02x F:%#02x SP:%#02x \t [%d]",
               cpu_state.program_counter,
               op,
               get_op_code_name(op),
@@ -77,6 +78,12 @@ void oam_dma_upload() {
 }
 
 void cpu_cycle() {
+    if (cpu_state.busy_cycle_count > 0) {
+        // The last operation is not done yet
+        cpu_state.busy_cycle_count--;
+        return;
+    }
+
     if (cpu_state.nmi_requested) {
         cpu_process_nmi();
     }
@@ -87,16 +94,13 @@ void cpu_cycle() {
         return;
     }
 
-    CPU cpu = cpu_state;
     byte op = cpu_get_next_byte();
-
     print_registers(op, system_get_cycles());
-
     process_op_code(op);
 }
 
 void cpu_add_cycles(unsigned int cycle_count) {
-    system_add_cycles(cycle_count);
+    cpu_state.busy_cycle_count += cycle_count;
 }
 
 // === Registers ===

cpu/cpu.h

@@ -29,6 +29,8 @@ typedef struct cpu {
     byte status;
     bool oam_dma_triggered;
     bool nmi_requested;
+
+    unsigned int busy_cycle_count;
 } CPU;
 
 CPU *cpu_get_state();

gui/CMakeLists.txt

@@ -0,0 +1,9 @@
+set(HEADERS canvas.h gui.h)
+set(SOURCE canvas.c gui.c)
+
+add_library(nes_gui ${SOURCE} ${HEADERS})
+
+find_package(SDL2 REQUIRED)
+include_directories(nes_gui ${SDL2_INCLUDE_DIRS})
+
+target_link_libraries(nes_gui log.c ${SDL2_LIBRARIES})

gui/canvas.c

@@ -0,0 +1,21 @@
+//
+// Created by william on 16/05/24.
+//
+
+#include <assert.h>
+#include <string.h>
+#include "canvas.h"
+
+void canvas_draw(Canvas *canvas, Pixel pixel, int x, int y) {
+    assert(x >= 0);
+    assert(x < CANVAS_WIDTH);
+    assert(y >= 0);
+    assert(y < CANVAS_HEIGHT);
+
+    int pixel_index = CANVAS_INDEX(x, y);
+    canvas->pixels[pixel_index] = pixel;
+}
+
+void canvas_reset(Canvas *canvas) {
+    memset(canvas->pixels, 0, sizeof(Pixel) * CANVAS_PIXEL_COUNT);
+}

gui/canvas.h

@@ -0,0 +1,29 @@
+//
+// Created by william on 16/05/24.
+//
+
+#ifndef NES_EMULATOR_CANVAS_H
+#define NES_EMULATOR_CANVAS_H
+
+#include "../include/types.h"
+
+#define CANVAS_WIDTH 256
+#define CANVAS_HEIGHT 240
+#define CANVAS_PIXEL_COUNT (CANVAS_WIDTH * CANVAS_HEIGHT)
+
+#define CANVAS_INDEX(x, y) (y * CANVAS_WIDTH + x)
+
+typedef struct pixel {
+    byte r;
+    byte g;
+    byte b;
+} Pixel;
+
+typedef struct canvas {
+    Pixel pixels[CANVAS_PIXEL_COUNT];
+} Canvas;
+
+void canvas_draw(Canvas *canvas, Pixel pixel, int x, int y);
+void canvas_reset(Canvas *canvas);
+
+#endif //NES_EMULATOR_CANVAS_H

gui/gui.c

@@ -0,0 +1,85 @@
+//
+// Created by william on 16/05/24.
+//
+
+#include "gui.h"
+#include "log.h"
+
+NesGui gui;
+
+int gui_init() {
+    int renderer_flags = SDL_RENDERER_ACCELERATED;
+    int window_flags = 0;
+
+    if (SDL_Init(SDL_INIT_VIDEO) < 0) {
+        log_error("Couldn't initialize SDL: %s", SDL_GetError());
+        return -1;
+    }
+
+    gui.window = SDL_CreateWindow("NES Emulator", SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, GUI_WIDTH,
+                                  GUI_HEIGHT, window_flags);
+    if (!gui.window) {
+        log_error("Failed to open %d x %d window: %s", GUI_WIDTH, GUI_HEIGHT, SDL_GetError());
+        return -1;
+    }
+
+    SDL_SetHint(SDL_HINT_RENDER_SCALE_QUALITY, "linear");
+
+    gui.renderer = SDL_CreateRenderer(gui.window, -1, renderer_flags);
+    if (!gui.renderer) {
+        log_error("Failed to create renderer: %s\n", SDL_GetError());
+        return -1;
+    }
+
+    return 1;
+}
+
+int gui_input() {
+    SDL_Event event;
+
+    while (SDL_PollEvent(&event)) {
+        switch (event.type) {
+            case SDL_QUIT:
+                return -1;
+            default:
+                break;
+        }
+    }
+
+    return 1;
+}
+
+void gui_prepare() {
+    SDL_SetRenderDrawColor(gui.renderer, 96, 128, 255, 255);
+    SDL_RenderClear(gui.renderer);
+}
+
+void gui_render() {
+    for (int x = 0; x < CANVAS_WIDTH; x++) {
+        for (int y = 0; y < CANVAS_HEIGHT; y++) {
+            int pixel_index = CANVAS_INDEX(x, y);
+            Pixel pixel = gui.canvas.pixels[pixel_index];
+
+            SDL_SetRenderDrawColor(gui.renderer, pixel.r, pixel.g, pixel.b, 255);
+
+            for (int i = 0; i < GUI_SCALING; i++) {
+                for (int j = 0; j < GUI_SCALING; j++) {
+                    int scaled_x = x * GUI_SCALING + i;
+                    int scaled_y = y * GUI_SCALING + j;
+                    SDL_RenderDrawPoint(gui.renderer, scaled_x, scaled_y);
+                }
+            }
+        }
+    }
+}
+
+void gui_present() {
+    SDL_RenderPresent(gui.renderer);
+}
+
+void gui_uninit() {
+}
+
+Canvas *gui_get_canvas() {
+    return &gui.canvas;
+}

gui/gui.h

@@ -0,0 +1,30 @@
+//
+// Created by william on 16/05/24.
+//
+
+#ifndef NES_EMULATOR_GUI_H
+#define NES_EMULATOR_GUI_H
+
+#include <SDL.h>
+#include "canvas.h"
+
+#define GUI_SCALING 3
+#define GUI_WIDTH CANVAS_WIDTH * GUI_SCALING
+#define GUI_HEIGHT CANVAS_HEIGHT * GUI_SCALING
+
+typedef struct nes_gui {
+    SDL_Renderer *renderer;
+    SDL_Window *window;
+    Canvas canvas;
+} NesGui;
+
+int gui_init();
+int gui_input();
+void gui_prepare();
+void gui_render();
+void gui_present();
+void gui_uninit();
+
+Canvas *gui_get_canvas();
+
+#endif //NES_EMULATOR_GUI_H

include/system.h

@@ -9,11 +9,13 @@
 #ifndef NESEMULATOR_SYSTEM_H
 #define NESEMULATOR_SYSTEM_H
 
-// NTSC NES Master Clock (~21.47 MHz)
-#define MASTER_CLOCK 21477272
-#define CPU_CLOCK_DIVISOR 12
-#define PPU_CLOCK_DIVISOR 4
 #define FRAME_RATE 60
+#define MASTER_CLOCK 21477272   // NTSC NES Master Clock (~21.47 MHz)
+#define MASTER_CYCLE_PER_FRAME (MASTER_CLOCK / FRAME_RATE)
+#define CPU_CLOCK_DIVISOR 12
+#define CPU_CYCLE_PER_FRAME (MASTER_CYCLE_PER_FRAME / CPU_CLOCK_DIVISOR)
+#define PPU_CLOCK_DIVISOR 4
+#define PPU_CYCLE_PER_CPU_CYCLE (CPU_CLOCK_DIVISOR / PPU_CLOCK_DIVISOR)
 
 #define PPU_REGISTERS_BASE_ADDR 0x2000
 #define PPU_REGISTER_OAM_DMA_ADDR 0x4014
@@ -33,6 +35,8 @@ void system_init();
 
 void system_start();
 
+void system_next_frame();
+
 /**
  * Starts the main loop of a system.
  */
@@ -44,6 +48,7 @@ void system_loop();
 void system_uninit();
 
 unsigned int system_get_cycles();
+
 void system_add_cycles(unsigned int cycles);
 
 Mapper *system_get_mapper();

main.c

@@ -21,22 +21,41 @@
 
 #include "include/rom.h"
 #include "include/system.h"
+#include "gui.h"
 
 int main() {
     log_set_level(LOG_INFO);
-    system_init();
 
-    char *rom_path = "../test_roms/dk_japan.nes";
+    system_init();
+    char *rom_path = "../test_roms/dk_jp.nes";
 
     if (!rom_load(rom_path)) {
         system_uninit();
         return EXIT_FAILURE;
     }
 
+    gui_init();
     system_start();
-//    start_debugger();
-    system_loop();
+
+    bool stop = false;
+    while (!stop) {
+        gui_prepare();
+
+        if (gui_input() < 0) {
+            stop = true;
+        }
+
+        system_next_frame();
+
+        gui_render();
+        gui_present();
+
+        SDL_Delay(16);
+    }
 
     system_uninit();
+    gui_uninit();
+
+////    start_debugger();
     return EXIT_SUCCESS;
 }

system.c

@@ -27,31 +27,13 @@ void system_start() {
     cpu_get_state()->program_counter = pc;
 }
 
-void system_loop() {
-    assert(CPU_CLOCK_DIVISOR > PPU_CLOCK_DIVISOR);
+void system_next_frame() {
+    for (int cpu_c = 0; cpu_c < CPU_CYCLE_PER_FRAME; cpu_c++) {
+        cpu_cycle();
 
-    unsigned int master_cycle_per_frame = MASTER_CLOCK / FRAME_RATE;
-    unsigned int cpu_cycle_per_frame = master_cycle_per_frame / CPU_CLOCK_DIVISOR;
-    unsigned int ppu_cycle_per_cpu_cycle = CPU_CLOCK_DIVISOR / PPU_CLOCK_DIVISOR;
-
-    long frame = 1;
-    long cpu_cycle_count = 0;
-    while (true) {
-//        log_info("Frame %d", frame);
-
-        while (current_sys.cycle_count < cpu_cycle_per_frame * frame) {
-            if (cpu_cycle_count == current_sys.cycle_count) {
-                cpu_cycle();
-            }
-            cpu_cycle_count++;
-
-            for (int ppu_c = 0; ppu_c < ppu_cycle_per_cpu_cycle; ppu_c++) {
-                ppu_cycle();
-            }
+        for (int ppu_c = 0; ppu_c < PPU_CYCLE_PER_CPU_CYCLE; ppu_c++) {
+            ppu_cycle();
         }
-
-        frame++;
-        usleep(17000); // Wait 16.6666ms
     }
 }