M include/mgba/core/interface.h → include/mgba/core/interface.h

@@ -31,6 +31,9 @@ #define M_R8(X) (((((X) << 3) & 0xF8) * 0x21) >> 5)
 #define M_G8(X) (((((X) >> 2) & 0xF8) * 0x21) >> 5)
 #define M_B8(X) (((((X) >> 7) & 0xF8) * 0x21) >> 5)
 
+#define M_RGB5_TO_RGB8(X) ((M_R5(X) << 3) | (M_G5(X) << 11) | (M_B5(X) << 19))
+#define M_RGB8_TO_RGB5(X) ((((X) & 0xF8) >> 3) | (((X) & 0xF800) >> 6) | (((X) & 0xF80000) >> 9))
+
 struct blip_t;
 
 struct mCoreCallbacks {

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

@@ -144,7 +144,7 @@ void GBVideoWriteLYC(struct GBVideo* video, uint8_t value);
 void GBVideoWritePalette(struct GBVideo* video, uint16_t address, uint8_t value);
 void GBVideoSwitchBank(struct GBVideo* video, uint8_t value);
 
-void GBVideoSetPalette(struct GBVideo* video, unsigned index, uint16_t color);
+void GBVideoSetPalette(struct GBVideo* video, unsigned index, uint32_t color);
 
 struct GBSerializedState;
 void GBVideoSerialize(const struct GBVideo* video, struct GBSerializedState* state);

M src/gb/video.c → src/gb/video.c

@@ -471,11 +471,11 @@ video->vramBank = &video->vram[value * GB_SIZE_VRAM_BANK0];
 	video->vramCurrentBank = value;
 }
 
-void GBVideoSetPalette(struct GBVideo* video, unsigned index, uint16_t color) {
+void GBVideoSetPalette(struct GBVideo* video, unsigned index, uint32_t color) {
 	if (index >= 4) {
 		return;
 	}
-	video->dmgPalette[index] = color;
+	video->dmgPalette[index] = M_RGB8_TO_RGB5(color);
 }
 
 static void GBVideoDummyRendererInit(struct GBVideoRenderer* renderer, enum GBModel model) {