Implement EEPROM

src/gba/gba-memory.c

@@ -164,10 +164,15 @@ int16_t GBALoad16(struct ARMMemory* memory, uint32_t address) {
 	case BASE_CART1:
 	case BASE_CART1_EX:
 	case BASE_CART2:
-	case BASE_CART2_EX:
 		if ((address & (SIZE_CART0 - 1)) < gbaMemory->romSize) {
 			return ((int16_t*) gbaMemory->rom)[(address & (SIZE_CART0 - 1)) >> 1];
 		}
+	case BASE_CART2_EX:
+		if (gbaMemory->savedata.type == SAVEDATA_EEPROM) {
+			return GBASavedataReadEEPROM(&gbaMemory->savedata);
+		} else if ((address & (SIZE_CART0 - 1)) < gbaMemory->romSize) {
+			return ((uint16_t*) gbaMemory->rom)[(address & (SIZE_CART0 - 1)) >> 1];
+		}
 	case BASE_CART_SRAM:
 		break;
 	default:
@@ -200,10 +205,15 @@ uint16_t GBALoadU16(struct ARMMemory* memory, uint32_t address) {
 	case BASE_CART1:
 	case BASE_CART1_EX:
 	case BASE_CART2:
-	case BASE_CART2_EX:
 		if ((address & (SIZE_CART0 - 1)) < gbaMemory->romSize) {
 			return ((uint16_t*) gbaMemory->rom)[(address & (SIZE_CART0 - 1)) >> 1];
 		}
+	case BASE_CART2_EX:
+		if (gbaMemory->savedata.type == SAVEDATA_EEPROM) {
+			return GBASavedataReadEEPROM(&gbaMemory->savedata);
+		} else if ((address & (SIZE_CART0 - 1)) < gbaMemory->romSize) {
+			return ((uint16_t*) gbaMemory->rom)[(address & (SIZE_CART0 - 1)) >> 1];
+		}
 	case BASE_CART_SRAM:
 		break;
 	default:
@@ -356,7 +366,7 @@ void GBAStore16(struct ARMMemory* memory, uint32_t address, int16_t value) {
 		if (gbaMemory->savedata.type == SAVEDATA_NONE) {
 			GBASavedataInitEEPROM(&gbaMemory->savedata);
 		}
-		GBASavedataWriteEEPROM(&gbaMemory->savedata, value);
+		GBASavedataWriteEEPROM(&gbaMemory->savedata, value, 1);
 		break;
 	case BASE_CART_SRAM:
 		break;
@@ -598,19 +608,23 @@ void GBAMemoryServiceDMA(struct GBAMemory* memory, int number, struct GBADMA* in
 		}
 	} else {
 		uint16_t word;
-		if (source >> BASE_OFFSET == BASE_CART2_EX && memory->savedata.type == SAVEDATA_EEPROM) {
+		if (sourceRegion == REGION_CART2_EX && memory->savedata.type == SAVEDATA_EEPROM) {
 			while (wordsRemaining--) {
 				word = GBASavedataReadEEPROM(&memory->savedata);
 				GBAStore16(&memory->d, dest, word);
 				source += sourceOffset;
 				dest += destOffset;
 			}
-		} else if (dest >> BASE_OFFSET == BASE_CART2_EX && memory->savedata.type == SAVEDATA_EEPROM) {
+		} else if (destRegion == REGION_CART2_EX) {
-			while (wordsRemaining--) {
+			if (memory->savedata.type != SAVEDATA_EEPROM) {
+				GBASavedataInitEEPROM(&memory->savedata);
+			}
+			while (wordsRemaining) {
 				word = GBALoadU16(&memory->d, source);
-				GBASavedataWriteEEPROM(&memory->savedata, word);
+				GBASavedataWriteEEPROM(&memory->savedata, word, wordsRemaining);
 				source += sourceOffset;
 				dest += destOffset;
+				--wordsRemaining;
 			}
 		} else {
 			while (wordsRemaining--) {

src/gba/gba-savedata.c

@@ -96,14 +96,68 @@ void GBASavedataWriteFlash(struct GBASavedata* savedata, uint8_t value) {
 	GBALog(GBA_LOG_STUB, "Flash memory unimplemented");
 }
 
-void GBASavedataWriteEEPROM(struct GBASavedata* savedata, uint16_t value) {
+void GBASavedataWriteEEPROM(struct GBASavedata* savedata, uint16_t value, uint32_t writeSize) {
-	(void)(savedata);
+	switch (savedata->command) {
-	(void)(value);
+	// Read header
-	GBALog(GBA_LOG_STUB, "EEPROM unimplemented");
+	case EEPROM_COMMAND_NULL:
+	default:
+		savedata->command = value & 0x1;
+		break;
+	case EEPROM_COMMAND_PENDING:
+		savedata->command <<= 1;
+		savedata->command |= value & 0x1;
+		if (savedata->command == EEPROM_COMMAND_WRITE) {
+			savedata->addressBits = writeSize - 64 - 2;
+			savedata->writeAddress = 0;
+		} else {
+			savedata->addressBits = writeSize - 2;
+			savedata->readAddress = 0;
+		}
+		break;
+	// Do commands
+	case EEPROM_COMMAND_WRITE:
+		// Write
+		if (writeSize > 65) {
+			savedata->writeAddress <<= 1;
+			savedata->writeAddress |= (value & 0x1) << 6;
+		} else if (writeSize == 1) {
+			savedata->command = EEPROM_COMMAND_NULL;
+			savedata->writePending = 1;
+		} else {
+			uint8_t current = savedata->data[savedata->writeAddress >> 3];
+			current &= ~(1 << (0x7 - (savedata->writeAddress & 0x7)));
+			current |= (value & 0x1) << (0x7 - (savedata->writeAddress & 0x7));
+			savedata->data[savedata->writeAddress >> 3] = current;
+			++savedata->writeAddress;
+		}
+		break;
+	case EEPROM_COMMAND_READ_PENDING:
+		// Read
+		if (writeSize > 1) {
+			savedata->readAddress <<= 1;
+			if (value & 0x1) {
+				savedata->readAddress |= 0x40;
+			}
+		} else {
+			savedata->readBitsRemaining = 68;
+			savedata->command = EEPROM_COMMAND_READ;
+		}
+		break;
+	}
 }
 
 uint16_t GBASavedataReadEEPROM(struct GBASavedata* savedata) {
-	(void)(savedata);
+	if (savedata->command != EEPROM_COMMAND_READ) {
-	GBALog(GBA_LOG_STUB, "EEPROM unimplemented");
+		return 1;
+	}
+	--savedata->readBitsRemaining;
+	if (savedata->readBitsRemaining < 64) {
+		int step = 63 - savedata->readBitsRemaining;
+		uint8_t data = savedata->data[(savedata->readAddress + step) >> 3] >> (0x7 - (step & 0x7));
+		if (!savedata->readBitsRemaining) {
+			savedata->command = EEPROM_COMMAND_NULL;
+		}
+		return data & 0x1;
+	}
 	return 0;
 }

src/gba/gba-savedata.h

@@ -11,6 +11,14 @@ enum SavedataType {
 	SAVEDATA_EEPROM
 };
 
+enum SavedataCommand {
+	EEPROM_COMMAND_NULL = 0,
+	EEPROM_COMMAND_PENDING = 1,
+	EEPROM_COMMAND_WRITE = 2,
+	EEPROM_COMMAND_READ_PENDING = 3,
+	EEPROM_COMMAND_READ = 4
+};
+
 enum {
 	SAVEDATA_FLASH_BASE = 0x0E005555
 };
@@ -19,7 +27,14 @@ struct GBASavedata {
 	enum SavedataType type;
 	uint8_t* data;
 	const char* filename;
+	enum SavedataCommand command;
 	int fd;
+
+	int readBitsRemaining;
+	int readAddress;
+	int writeAddress;
+	int writePending;
+	int addressBits;
 };
 
 void GBASavedataInit(struct GBASavedata* savedata, const char* filename);
@@ -32,6 +47,6 @@ void GBASavedataInitSRAM(struct GBASavedata* savedata);
 void GBASavedataWriteFlash(struct GBASavedata* savedata, uint8_t value);
 
 uint16_t GBASavedataReadEEPROM(struct GBASavedata* savedata);
-void GBASavedataWriteEEPROM(struct GBASavedata* savedata, uint16_t value);
+void GBASavedataWriteEEPROM(struct GBASavedata* savedata, uint16_t value, uint32_t writeSize);
 
 #endif