Add tile debugger to main view

README.md

@@ -11,6 +11,7 @@ only tested on Linux. Here is how to run the project:
 ## Controls
  - `p`: Pauses the emulation
  - `o`: Go to the next palette in the pattern viewer
+ - `t`: Show tile IDs
 
 ## Dependencies
  - GCC compiler

gui/gui.c

@@ -89,7 +89,12 @@ int gui_input() {
                 system_toggle_pause();
             } else {
 #if DEBUG
-                pattern_window_key_up(&gui.pattern_window, event.key.keysym.sym);
+                if (event.key.keysym.sym == SDLK_t) {
+                    PPUDebugFlags *ppu_debug = &ppu_get_state()->debug;
+                    ppu_debug->flags.tile_debugger = !ppu_debug->flags.tile_debugger;
+                } else {
+                    pattern_window_key_up(&gui.pattern_window, event.key.keysym.sym);
+                }
 #endif
             }
         }

gui/main_window.c

@@ -34,20 +34,8 @@ void main_window_render_delay(SDL_Renderer *renderer) {
 }
 #endif
 
-void main_window_render(NesMainWindow *window, PPUPixel *pixels) {
+void main_window_render(NesMainWindow *window, pixel *pixels) {
     SDL_RenderClear(window->sdl_context.renderer);
-
-//    unsigned int frame_buffer[240 * 256];
-//    for (int i = 0; i < 240 * 256; i++) {
-//        PPUPixel pixel = pixels[i];
-//
-//        unsigned int *data = &frame_buffer[i];
-//        *data = 0xff000000;
-//        *data |= pixel.r << 16;
-//        *data |= pixel.g << 8;
-//        *data |= pixel.b;
-//    }
-
     SDL_UpdateTexture(window->texture, NULL, pixels, 240 * sizeof(unsigned int));
     SDL_RenderCopy(window->sdl_context.renderer, window->texture, NULL, NULL);
 

gui/main_window.h

@@ -11,7 +11,7 @@
 
 #define MAIN_WINDOW_WIDTH 256
 #define MAIN_WINDOW_HEIGHT 240
-#define MAIN_WINDOW_SCALE 2
+#define MAIN_WINDOW_SCALE 3
 
 typedef struct nes_main_window {
     NesSdlContext sdl_context;
@@ -22,7 +22,7 @@ typedef struct nes_main_window {
 void main_window_init(NesMainWindow *window);
 void main_window_uninit(NesMainWindow *window);
 
-void main_window_render(NesMainWindow *window, PPUPixel* pixels);
+void main_window_render(NesMainWindow *window, pixel* pixels);
 void main_window_present(NesMainWindow *window);
 
 #endif //NES_EMULATOR_MAIN_WINDOW_H

include/ppu.h

@@ -69,46 +69,42 @@ typedef struct ppu_tile_fetch {
     byte pattern_table_tile_high;
 } PPUTileFetch;
 
-//typedef struct ppu_pixel {
-//    byte r;
-//    byte g;
-//    byte b;
-//} PPUPixel;
-typedef unsigned int PPUPixel;
-
-typedef struct ppu_tile_queue {
-    PPUTileFetch first_fetch;
-    PPUTileFetch second_fetch;
-    PPUTileFetch displayed_fetch;
-} PPUTileQueue;
+#if DEBUG
+typedef union {
+    struct {
+        byte tile_debugger: 1;
+    } flags;
+    byte flags_byte;
+} PPUDebugFlags;
+#endif
 
 typedef struct ppu {
     PPUMemory memory;
-    PPUPixel pixels[256 * 240];
+    pixel pixels[256 * 240];
 
     byte registers[8];
     byte oam_dma_register;
     byte oam[PPU_OAM_SIZE];
     bool odd_frame;
-    address v;
-    address t;
-    byte x;
-    bool w;
-
     byte x_scroll;
     byte fine_x_scroll;
     byte y_scroll;
-    byte ppu_addr_increment;
+    byte x;
+    bool w;
 
+    byte ppu_addr_increment;
     address ppu_address;
     address temp_ppu_addr;
     address bg_pattern_table_addr;
 
     PPUTileFetch fetch;
-    PPUTileQueue tile_queue;
     unsigned long frame;
     unsigned int scanline;
     unsigned int cycle;
+
+#if DEBUG
+    PPUDebugFlags debug;
+#endif
 } PPU;
 
 PPU *ppu_get_state();
@@ -137,17 +133,6 @@ void ppu_cycle();
  */
 bool ppu_read_flag(size_t reg, byte mask);
 
-/**
- * Read a value from the PPU registers. Does not apply any offset to the value, a mask of 0x20 will either result in 0x20 (true) or 0x0 (false).
- * Read a value from the PPU registers. Does not apply any offset to the value, a mask of 0x20 will either result in 0x20 (true) or 0x0 (false).
- *
- * @param reg The register index
- * @param mask The value mask
- */
-//void ppu_sig_read_register(byte reg);
-//
-//void ppu_sig_write_register(byte reg);
-
 byte ppu_read_reg(byte reg);
 
 void ppu_write_reg(byte reg, byte data);

include/types.h

@@ -5,14 +5,9 @@
 #ifndef NESEMULATOR_TYPES_H
 #define NESEMULATOR_TYPES_H
 
-//#define RAM_SIZE 0xffff
-//#define VRAM_SIZE 0x4000
-
 typedef unsigned char byte;
 typedef unsigned short address;
 typedef unsigned short word;
-
-//typedef byte ram[RAM_SIZE];
-//typedef byte vram[VRAM_SIZE];
+typedef unsigned int pixel;
 
 #endif //NESEMULATOR_TYPES_H

ppu/ppu.c

@@ -20,6 +20,7 @@
 #include "../cpu/cpu.h"
 #include "../include/rom.h"
 #include "colors.h"
+#include "tile_debugger.h"
 
 #define PPU_VISIBLE_FRAME_END 240
 #define PPU_POST_RENDER_LINE_START PPU_VISIBLE_FRAME_END
@@ -31,7 +32,7 @@
 #define NAMETABLE_TILE_SIZE 8
 
 PPU ppu_state;
-PPUPixel color_list[0x40] = COLOR_LIST;
+pixel color_list[0x40] = COLOR_LIST;
 
 void ppu_init() {
     memset(&ppu_state, 0, sizeof(PPU));
@@ -95,7 +96,7 @@ static inline byte ppu_pixel_get_palette(byte attribute) {
     return palette & 0b11;
 }
 
-static inline void ppu_pixel_set_color(PPUPixel *pixel, byte pt_low, byte pt_high, byte attribute) {
+static inline void ppu_pixel_set_color(pixel *pixel, byte pt_low, byte pt_high, byte attribute) {
     for (int i = 0; i < 8; i++) {
         byte pixel_offset = 8 - i - 1;
 
@@ -114,7 +115,7 @@ static inline void ppu_pixel_set_color(PPUPixel *pixel, byte pt_low, byte pt_hig
 }
 
 void ppu_draw_tile() {
-    PPUTileFetch fetch = ppu_state.tile_queue.displayed_fetch;
+    PPUTileFetch fetch = ppu_state.fetch;
 
     unsigned int y = ppu_state.scanline;
     unsigned int x = ppu_state.cycle;
@@ -129,15 +130,20 @@ void ppu_draw_tile() {
 //    }
 
     unsigned int pixel_index = y * PPU_VISIBLE_FRAME_END + x;
-    PPUPixel *pixel = &ppu_state.pixels[pixel_index];
+    pixel *pixel = &ppu_state.pixels[pixel_index];
     ppu_pixel_set_color(pixel, fetch.pattern_table_tile_low, fetch.pattern_table_tile_high, fetch.attribute_table);
 }
 
 byte ppu_get_pattern(byte tile_index, byte high) {
-    return tile_index;
-//    byte tile_row_index = (ppu_state.scanline + ppu_state.y_scroll) % 8;
-//    address pattern_addr = ppu_state.bg_pattern_table_addr | tile_index << 4 | high << 3 | tile_row_index;
-//    return ppu_read(pattern_addr);
+#if DEBUG
+    if (ppu_state.debug.flags.tile_debugger) {
+        return tile_debugger_encode_number_as_pattern(tile_index, ppu_state.scanline % 8);
+    }
+#endif
+
+    byte tile_row_index = (ppu_state.scanline + ppu_state.y_scroll) % 8;
+    address pattern_addr = ppu_state.bg_pattern_table_addr | tile_index << 4 | high << 3 | tile_row_index;
+    return ppu_read(pattern_addr);
 }
 
 void ppu_fetch_tile(bool render) {
@@ -169,7 +175,6 @@ void ppu_fetch_tile(bool render) {
         ppu_state.fetch.pattern_table_tile_low = ppu_get_pattern(ppu_state.fetch.nametable, 0);
     } else if (fetch_cycle == 7) {
         ppu_state.fetch.pattern_table_tile_high = ppu_get_pattern(ppu_state.fetch.nametable, 1);
-        ppu_state.tile_queue.displayed_fetch = ppu_state.fetch;
 
         if (render) {
             ppu_draw_tile();

ppu/tile_debugger.c

@@ -4,7 +4,34 @@
 
 #include "tile_debugger.h"
 
-byte tile_encode_number(byte num) {
-    // 8 segment display
+// Contains the patterns of every hexadecimal digit encoded as pattern data.
+// The first dimension of the table represents a row in a tile.
+byte hex_pattern_table[5][0x10] = {
+        {0b111, 0b001, 0b111, 0b111, 0b101, 0b111, 0b111, 0b111, 0b111, 0b111, 0b010, 0b111, 0b111, 0b110, 0b111, 0b111},
+        {0b101, 0b001, 0b001, 0b001, 0b101, 0b100, 0b100, 0b001, 0b101, 0b101, 0b101, 0b101, 0b100, 0b101, 0b100, 0b100},
+        {0b101, 0b001, 0b111, 0b111, 0b111, 0b111, 0b111, 0b010, 0b111, 0b111, 0b111, 0b110, 0b100, 0b101, 0b111, 0b110},
+        {0b101, 0b001, 0b100, 0b001, 0b001, 0b001, 0b101, 0b010, 0b101, 0b001, 0b101, 0b101, 0b100, 0b101, 0b100, 0b100},
+        {0b111, 0b001, 0b111, 0b111, 0b001, 0b111, 0b111, 0b010, 0b111, 0b001, 0b101, 0b111, 0b111, 0b110, 0b111, 0b100},
+};
 
+byte tile_debugger_encode_number_as_pattern(byte num, byte tile_fine_y) {
+    if (tile_fine_y == 6) {
+        return 0x7f;    // On row 6, a full line is drawn to make it easier to separate tiles
+    } else if (tile_fine_y == 5 || tile_fine_y == 7) {
+        return 0;
+    }
+
+    // The first digit of the hex is encoded
+    byte remaining = num % 0x10;
+    byte encoded = hex_pattern_table[tile_fine_y][remaining];
+
+    if (num > 0xf) {
+        // If the number is greater than 0xF, we need a second digit
+        // We encode it, then add it 4 pixels to the left of the already encoded digit
+        byte tenths = num / 0x10;
+        byte tenths_encoded = hex_pattern_table[tile_fine_y][tenths];
+        encoded = (tenths_encoded << 4) | encoded;
+    }
+
+    return encoded;
 }

ppu/tile_debugger.h

@@ -7,4 +7,13 @@
 
 #include "../include/types.h"
 
+/**
+ * Encodes a number as pattern data.
+ *
+ * @param num The number to encode
+ * @param tile_fine_y The row of the tile
+ * @return Pattern data representing the row of the encoded number
+ */
+byte tile_debugger_encode_number_as_pattern(byte num, byte tile_fine_y);
+
 #endif //NES_EMULATOR_TILE_DEBUGGER_H