M include/mgba/internal/ds/video.h → include/mgba/internal/ds/video.h

@@ -64,6 +64,8 @@ DECL_BITFIELD(DSRegisterPOWCNT1, uint16_t);
 // TODO
 DECL_BIT(DSRegisterPOWCNT1, Swap, 15);
 
+DECL_BIT(GBARegisterBGCNT, ExtendedMode0, 2);
+DECL_BIT(GBARegisterBGCNT, ExtendedMode1, 7);
 DECL_BIT(GBARegisterBGCNT, ExtPaletteSlot, 13);
 
 DECL_BITFIELD(DSRegisterMASTER_BRIGHT, uint16_t);

M src/ds/renderers/software.c → src/ds/renderers/software.c

@@ -414,7 +414,11 @@ case 4:
 					GBAVideoSoftwareRendererDrawBackgroundMode2(softwareRenderer, &softwareRenderer->bg[2], y);
 					break;
 				case 5:
-					DSVideoSoftwareRendererDrawBackgroundExt0(softwareRenderer, &softwareRenderer->bg[2], y);
+					if (!GBARegisterBGCNTIsExtendedMode1(softwareRenderer->bg[2].control)) {
+						DSVideoSoftwareRendererDrawBackgroundExt0(softwareRenderer, &softwareRenderer->bg[2], y);
+					} else {
+						// TODO
+					}
 					break;
 				}
 			}
@@ -430,7 +434,11 @@ break;
 				case 3:
 				case 4:
 				case 5:
-					DSVideoSoftwareRendererDrawBackgroundExt0(softwareRenderer, &softwareRenderer->bg[3], y);
+					if (!GBARegisterBGCNTIsExtendedMode1(softwareRenderer->bg[3].control)) {
+						DSVideoSoftwareRendererDrawBackgroundExt0(softwareRenderer, &softwareRenderer->bg[3], y);
+					} else {
+						// TODO
+					}
 					break;
 				}
 			}
@@ -659,7 +667,10 @@ BACKGROUND_BITMAP_INIT;
 
 	color_t* mainPalette = background->extPalette;
 	if (variant) {
-		palette = background->variantPalette;
+		mainPalette = background->variantPalette;
+	}
+	if (!mainPalette) {
+		return;
 	}
 	int paletteData;