Add LoadFontGraphics function and update Load2BppGraphics sheet IDs

- Introduced LoadFontGraphics function to handle font graphics loading from ROM data.
- Updated Load2BppGraphics to use hex sheet IDs.

src/app/rom.cc

@@ -39,8 +39,7 @@ uint32_t GetGraphicsAddress(const uint8_t *data, uint8_t addr, uint32_t ptr1,
 
 absl::StatusOr<std::vector<uint8_t>> Load2BppGraphics(const Rom &rom) {
   std::vector<uint8_t> sheet;
-  const uint8_t sheets[] = {113, 114, 218, 219, 220, 221};
-
+  const uint8_t sheets[] = {0x71, 0x72, 0xDA, 0xDB, 0xDC, 0xDD, 0xDE};
   for (const auto &sheet_id : sheets) {
     auto offset = GetGraphicsAddress(rom.data(), sheet_id,
                                      rom.version_constants().kOverworldGfxPtr1,
@@ -75,6 +74,64 @@ absl::StatusOr<std::array<gfx::Bitmap, kNumLinkSheets>> LoadLinkGraphics(
   return link_graphics;
 }
 
+absl::StatusOr<gfx::Bitmap> LoadFontGraphics(const Rom &rom) {
+  std::vector<uint8_t> data(0x2000);
+  for (int i = 0; i < 0x2000; i++) {
+    data[i] = rom.data()[0x70000 + i];
+  }
+
+  std::vector<uint8_t> new_data(0x4000);
+  std::vector<uint8_t> mask = {0x80, 0x40, 0x20, 0x10, 0x08, 0x04, 0x02, 0x01};
+  int sheet_position = 0;
+
+  // 8x8 tile
+  for (int s = 0; s < 4; s++) {        // Per Sheet
+    for (int j = 0; j < 4; j++) {      // Per Tile Line Y
+      for (int i = 0; i < 16; i++) {   // Per Tile Line X
+        for (int y = 0; y < 8; y++) {  // Per Pixel Line
+          uint8_t line_bits0 =
+              data[(y * 2) + (i * 16) + (j * 256) + sheet_position];
+          uint8_t line_bits1 =
+              data[(y * 2) + (i * 16) + (j * 256) + 1 + sheet_position];
+
+          for (int x = 0; x < 4; x++) {  // Per Pixel X
+            uint8_t pixdata = 0;
+            uint8_t pixdata2 = 0;
+
+            if ((line_bits0 & mask[(x * 2)]) == mask[(x * 2)]) {
+              pixdata += 1;
+            }
+            if ((line_bits1 & mask[(x * 2)]) == mask[(x * 2)]) {
+              pixdata += 2;
+            }
+
+            if ((line_bits0 & mask[(x * 2) + 1]) == mask[(x * 2) + 1]) {
+              pixdata2 += 1;
+            }
+            if ((line_bits1 & mask[(x * 2) + 1]) == mask[(x * 2) + 1]) {
+              pixdata2 += 2;
+            }
+
+            new_data[(y * 64) + (x) + (i * 4) + (j * 512) + (s * 2048)] =
+                (uint8_t)((pixdata << 4) | pixdata2);
+          }
+        }
+      }
+    }
+
+    sheet_position += 0x400;
+  }
+
+  std::vector<uint8_t> fontgfx16_data(0x4000);
+  for (int i = 0; i < 0x4000; i++) {
+    fontgfx16_data[i] = new_data[i];
+  }
+
+  gfx::Bitmap font_gfx;
+  font_gfx.Create(128, 128, 64, fontgfx16_data);
+  return font_gfx;
+}
+
 absl::StatusOr<std::array<gfx::Bitmap, kNumGfxSheets>> LoadAllGraphicsData(
     Rom &rom, bool defer_render) {
   std::array<gfx::Bitmap, kNumGfxSheets> graphics_sheets;