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

@@ -180,6 +180,7 @@ GBMemoryBankControllerWrite mbcWrite;
 	GBMemoryBankControllerRead mbcRead;
 	union GBMBCState mbcState;
 	int currentBank;
+	int currentBank0;
 
 	uint8_t* wram;
 	uint8_t* wramBank;

M src/gb/gb.c → src/gb/gb.c

@@ -113,7 +113,6 @@ if (!gb->memory.rom) {
 		return false;
 	}
 	gb->yankedRomSize = 0;
-	gb->memory.romBase = gb->memory.rom;
 	gb->memory.romSize = gb->pristineRomSize;
 	gb->romCrc32 = doCrc32(gb->memory.rom, gb->memory.romSize);
 	memset(&gb->memory.mbcState, 0, sizeof(gb->memory.mbcState));
@@ -294,9 +293,6 @@ }
 
 void GBUnloadROM(struct GB* gb) {
 	// TODO: Share with GBAUnloadROM
-	if (gb->memory.rom && gb->memory.romBase != gb->memory.rom && !gb->isPristine) {
-		free(gb->memory.romBase);
-	}
 	if (gb->memory.rom && !gb->isPristine) {
 		if (gb->yankedRomSize) {
 			gb->yankedRomSize = 0;
@@ -374,6 +370,7 @@ gb->cpu->memory.setActiveRegion(gb->cpu, gb->cpu->pc);
 }
 
 void GBDestroy(struct GB* gb) {
+	GBUnmapBIOS(gb);
 	GBUnloadROM(gb);
 
 	if (gb->biosVf) {
@@ -588,17 +585,18 @@ }
 
 void GBMapBIOS(struct GB* gb) {
 	gb->biosVf->seek(gb->biosVf, 0, SEEK_SET);
-	uint8_t* oldRomBase = gb->memory.romBase;
 	gb->memory.romBase = malloc(GB_SIZE_CART_BANK0);
 	ssize_t size = gb->biosVf->read(gb->biosVf, gb->memory.romBase, GB_SIZE_CART_BANK0);
-	memcpy(&gb->memory.romBase[size], &oldRomBase[size], GB_SIZE_CART_BANK0 - size);
-	if (size > 0x100) {
-		memcpy(&gb->memory.romBase[0x100], &oldRomBase[0x100], sizeof(struct GBCartridge));
+	if (gb->memory.rom) {
+		memcpy(&gb->memory.romBase[size], &gb->memory.rom[size], GB_SIZE_CART_BANK0 - size);
+		if (size > 0x100) {
+			memcpy(&gb->memory.romBase[0x100], &gb->memory.rom[0x100], sizeof(struct GBCartridge));
+		}
 	}
 }
 
 void GBUnmapBIOS(struct GB* gb) {
-	if (gb->memory.romBase < gb->memory.rom || gb->memory.romBase > &gb->memory.rom[gb->memory.romSize - 1]) {
+	if (gb->memory.io[GB_REG_BANK] == 0xFF && gb->memory.romBase != gb->memory.rom) {
 		free(gb->memory.romBase);
 		if (gb->memory.mbcType == GB_MMM01) {
 			GBMBCSwitchBank0(gb, gb->memory.romSize / GB_SIZE_CART_BANK0 - 2);

M src/gb/mbc.c → src/gb/mbc.c

@@ -76,6 +76,7 @@ mLOG(GB_MBC, GAME_ERROR, "Attempting to switch to an invalid ROM bank: %0X", bank);
 		bankStart &= (gb->memory.romSize - 1);
 	}
 	gb->memory.romBase = &gb->memory.rom[bankStart];
+	gb->memory.currentBank0 = bank;
 	if (gb->cpu->pc < GB_SIZE_CART_BANK0) {
 		gb->cpu->memory.setActiveRegion(gb->cpu, gb->cpu->pc);
 	}
@@ -436,6 +437,7 @@ }
 }
 
 void GBMBCReset(struct GB* gb) {
+	gb->memory.currentBank0 = 0;
 	gb->memory.romBank = &gb->memory.rom[GB_SIZE_CART_BANK0];
 
 	memset(&gb->memory.mbcState, 0, sizeof(gb->memory.mbcState));

M src/gb/serialize.c → src/gb/serialize.c

@@ -195,6 +195,7 @@ } else {
 		gb->audio.style = GB_AUDIO_CGB;
 	}
 
+	GBUnmapBIOS(gb);
 	GBMemoryDeserialize(gb, state);
 	GBVideoDeserialize(&gb->video, state);
 	GBIODeserialize(gb, state);
@@ -203,8 +204,6 @@ GBAudioDeserialize(&gb->audio, state);
 
 	if (gb->memory.io[GB_REG_BANK] == 0xFF) {
 		GBMapBIOS(gb);
-	} else {
-		GBUnmapBIOS(gb);
 	}
 
 	if (gb->model & GB_MODEL_SGB && canSgb) {