GB MBC: Add MMM01

CHANGES

@@ -15,7 +15,7 @@ Features:
  - Ability to select GB/GBC/SGB BIOS on console ports
  - Optional automatic state saving/loading
  - Access to ur0 and uma0 partitions on the Vita
- - Partial support for MBC6, TAMA and HuC-1 GB mappers
+ - Partial support for MBC6, MMM01, TAMA and HuC-1 GB mappers
 Bugfixes:
  - GB Audio: Make audio unsigned with bias (fixes mgba.io/i/749)
  - GB Serialize: Fix audio state loading

README.md

@@ -53,15 +53,12 @@ The following mappers are fully supported:
 The following mappers are partially supported:
 
 - MBC6
+- MMM01
 - Pocket Cam
 - TAMA5
 - HuC-1
 - HuC-3
 
-The following mappers are not currently supported:
-
-- MMM01
-
 ### Planned features
 
 - Networked multiplayer link cable support.

include/mgba/internal/gb/memory.h

@@ -129,6 +129,11 @@ struct GBMBC7State {
 	GBMBC7Field eeprom;
 };
 
+struct GBMMM01State {
+	bool locked;
+	int currentBank0;
+};
+
 struct GBPocketCamState {
 	bool registersActive;
 	uint8_t registers[0x36];
@@ -143,6 +148,7 @@ union GBMBCState {
 	struct GBMBC1State mbc1;
 	struct GBMBC6State mbc6;
 	struct GBMBC7State mbc7;
+	struct GBMMM01State mmm01;
 	struct GBPocketCamState pocketCam;
 	struct GBTAMA5State tama5;
 };

include/mgba/internal/gb/serialize.h

@@ -373,6 +373,10 @@ struct GBSerializedState {
 				uint16_t sr;
 				uint32_t writable;
 			} mbc7;
+			struct {
+				uint8_t locked;
+				uint8_t bank0;
+			} mmm01;
 			struct {
 				uint8_t reserved[16];
 			} padding;

src/gb/mbc.c

@@ -9,8 +9,11 @@
 #include <mgba/internal/lr35902/lr35902.h>
 #include <mgba/internal/gb/gb.h>
 #include <mgba/internal/gb/memory.h>
+#include <mgba-util/crc32.h>
 #include <mgba-util/vfs.h>
 
+const uint32_t GB_LOGO_HASH = 0x46195417;
+
 mLOG_DEFINE_CATEGORY(GB_MBC, "GB MBC", "gb.mbc");
 
 static void _GBMBCNone(struct GB* gb, uint16_t address, uint8_t value) {
@@ -27,6 +30,7 @@ static void _GBMBC3(struct GB*, uint16_t address, uint8_t value);
 static void _GBMBC5(struct GB*, uint16_t address, uint8_t value);
 static void _GBMBC6(struct GB*, uint16_t address, uint8_t value);
 static void _GBMBC7(struct GB*, uint16_t address, uint8_t value);
+static void _GBMMM01(struct GB*, uint16_t address, uint8_t value);
 static void _GBHuC1(struct GB*, uint16_t address, uint8_t value);
 static void _GBHuC3(struct GB*, uint16_t address, uint8_t value);
 static void _GBPocketCam(struct GB* gb, uint16_t address, uint8_t value);
@@ -135,6 +139,12 @@ void GBMBCSwitchSramHalfBank(struct GB* gb, int half, int bank) {
 void GBMBCInit(struct GB* gb) {
 	const struct GBCartridge* cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
 	if (gb->memory.rom) {
+		if (gb->memory.romSize >= 0x8000) {
+			const struct GBCartridge* cartFooter = (const struct GBCartridge*) &gb->memory.rom[gb->memory.romSize - 0x7F00];
+			if (doCrc32(cartFooter->logo, sizeof(cartFooter->logo)) == GB_LOGO_HASH) {
+				cart = cartFooter;
+			}
+		}
 		switch (cart->ramSize) {
 		case 0:
 			gb->sramSize = 0;
@@ -178,6 +188,11 @@ void GBMBCInit(struct GB* gb) {
 			case 6:
 				gb->memory.mbcType = GB_MBC2;
 				break;
+			case 0x0B:
+			case 0x0C:
+			case 0x0D:
+				gb->memory.mbcType = GB_MMM01;
+				break;
 			case 0x0F:
 			case 0x10:
 				gb->memory.mbcType = GB_MBC3_RTC;
@@ -256,8 +271,7 @@ void GBMBCInit(struct GB* gb) {
 		gb->sramSize = 0x100;
 		break;
 	case GB_MMM01:
-		mLOG(GB_MBC, WARN, "unimplemented MBC: MMM01");
-		gb->memory.mbcWrite = _GBMBC1;
+		gb->memory.mbcWrite = _GBMMM01;
 		break;
 	case GB_HuC1:
 		gb->memory.mbcWrite = _GBHuC1;
@@ -821,6 +835,49 @@ static void _GBMBC7Write(struct GBMemory* memory, uint16_t address, uint8_t valu
 	mbc7->eeprom = value;
 }
 
+void _GBMMM01(struct GB* gb, uint16_t address, uint8_t value) {
+	struct GBMemory* memory = &gb->memory;
+	if (!memory->mbcState.mmm01.locked) {
+		switch (address >> 13) {
+		case 0x0:
+			memory->mbcState.mmm01.locked = true;
+			GBMBCSwitchBank0(gb, memory->mbcState.mmm01.currentBank0);
+			break;
+		case 0x1:
+			memory->mbcState.mmm01.currentBank0 = value & 0x3F;
+			break;
+		default:
+			// TODO
+			mLOG(GB_MBC, STUB, "MMM01 unknown address: %04X:%02X", address, value);
+			break;
+		}
+		return;
+	}
+	switch (address >> 13) {
+	case 0x0:
+		switch (value) {
+		case 0xA:
+			memory->sramAccess = true;
+			GBMBCSwitchSramBank(gb, memory->sramCurrentBank);
+			break;
+		default:
+			memory->sramAccess = false;
+			break;
+		}
+		break;
+	case 0x1:
+		GBMBCSwitchBank(gb, value + memory->mbcState.mmm01.currentBank0);
+		break;
+	case 0x2:
+		GBMBCSwitchSramBank(gb, value);
+		break;
+	default:
+		// TODO
+		mLOG(GB_MBC, STUB, "MMM01 unknown address: %04X:%02X", address, value);
+		break;
+	}
+}
+
 void _GBHuC1(struct GB* gb, uint16_t address, uint8_t value) {
 	struct GBMemory* memory = &gb->memory;
 	int bank = value & 0x3F;

src/gb/memory.c

@@ -176,6 +176,8 @@ void GBMemoryReset(struct GB* gb) {
 	gb->memory.hdmaEvent.priority = 0x41;
 
 	memset(&gb->memory.hram, 0, sizeof(gb->memory.hram));
+
+	GBMBCInit(gb);
 	switch (gb->memory.mbcType) {
 	case GB_MBC1:
 		gb->memory.mbcState.mbc1.mode = 0;
@@ -187,11 +189,12 @@ void GBMemoryReset(struct GB* gb) {
 		GBMBCSwitchSramHalfBank(gb, 0, 0);
 		GBMBCSwitchSramHalfBank(gb, 0, 1);
 		break;
+	case GB_MMM01:
+		GBMBCSwitchBank0(gb, gb->memory.romSize / GB_SIZE_CART_BANK0 - 2);
+		GBMBCSwitchBank(gb, gb->memory.romSize / GB_SIZE_CART_BANK0 - 1);
 	default:
 		memset(&gb->memory.mbcState, 0, sizeof(gb->memory.mbcState));
 	}
-
-	GBMBCInit(gb);
 	gb->memory.sramBank = gb->memory.sram;
 
 	if (!gb->memory.wram) {
@@ -688,6 +691,10 @@ void GBMemorySerialize(const struct GB* gb, struct GBSerializedState* state) {
 		STORE_16LE(memory->mbcState.mbc7.sr, 0, &state->memory.mbc7.sr);
 		STORE_32LE(memory->mbcState.mbc7.writable, 0, &state->memory.mbc7.writable);
 		break;
+	case GB_MMM01:
+		state->memory.mmm01.locked = memory->mbcState.mmm01.locked;
+		state->memory.mmm01.bank0 = memory->mbcState.mmm01.currentBank0;
+		break;
 	default:
 		break;
 	}
@@ -755,6 +762,15 @@ void GBMemoryDeserialize(struct GB* gb, const struct GBSerializedState* state) {
 		LOAD_16LE(memory->mbcState.mbc7.sr, 0, &state->memory.mbc7.sr);
 		LOAD_32LE(memory->mbcState.mbc7.writable, 0, &state->memory.mbc7.writable);
 		break;
+	case GB_MMM01:
+		memory->mbcState.mmm01.locked = state->memory.mmm01.locked;
+		memory->mbcState.mmm01.currentBank0 = state->memory.mmm01.bank0;
+		if (memory->mbcState.mmm01.locked) {
+			GBMBCSwitchBank0(gb, memory->mbcState.mmm01.currentBank0);
+		} else {
+			GBMBCSwitchBank0(gb, gb->memory.romSize / GB_SIZE_CART_BANK0 - 2);
+		}
+		break;
 	default:
 		break;
 	}