GBA Savedata: Store RTC data in savegames (closes #240)

CHANGES

@@ -87,8 +87,9 @@ Misc:
  - GBA: Automatically skip BIOS if ROM has invalid logo
  - GBA: Refine multiboot detection (fixes mgba.io/i/2192)
  - GBA Cheats: Implement "never" type codes (closes mgba.io/i/915)
- - GBA Memory: Implement adjustable EWRAM waitstates (closes mgba.io/i/1276)
  - GBA DMA: Enhanced logging (closes mgba.io/i/2454)
+ - GBA Memory: Implement adjustable EWRAM waitstates (closes mgba.io/i/1276)
+ - GBA Savedata: Store RTC data in savegames (closes mgba.io/i/240)
  - GBA Video: Implement layer placement for OpenGL renderer (fixes mgba.io/i/1962)
  - GBA Video: Fix highlighting for sprites with mid-frame palette changes
  - mGUI: Add margin to right-aligned menu text (fixes mgba.io/i/871)

include/mgba/internal/gba/cart/gpio.h

@@ -42,7 +42,7 @@ enum GPIODirection {
 	GPIO_READ_WRITE = 1
 };
 
-DECL_BITFIELD(RTCControl, uint32_t);
+DECL_BITFIELD(RTCControl, uint8_t);
 DECL_BIT(RTCControl, MinIRQ, 3);
 DECL_BIT(RTCControl, Hour24, 6);
 DECL_BIT(RTCControl, Poweroff, 7);
@@ -69,6 +69,8 @@ struct GBARTC {
 	RTCCommandData command;
 	RTCControl control;
 	uint8_t time[7];
+	time_t lastLatch;
+	time_t offset;
 };
 
 DECL_BITFIELD(GPIOPin, uint16_t);

include/mgba/internal/gba/savedata.h

@@ -72,6 +72,7 @@ struct GBASavedata {
 	uint8_t* data;
 	enum SavedataCommand command;
 	struct VFile* vf;
+	struct GBACartridgeHardware* gpio;
 
 	int mapMode;
 	bool maskWriteback;
@@ -93,6 +94,12 @@ struct GBASavedata {
 	enum FlashStateMachine flashState;
 };
 
+struct GBASavedataRTCBuffer {
+	uint8_t time[7];
+	uint8_t control;
+	uint64_t lastLatch;
+};
+
 void GBASavedataInit(struct GBASavedata* savedata, struct VFile* vf);
 void GBASavedataDeinit(struct GBASavedata* savedata);
 
@@ -116,6 +123,9 @@ void GBASavedataWriteEEPROM(struct GBASavedata* savedata, uint16_t value, uint32
 
 void GBASavedataClean(struct GBASavedata* savedata, uint32_t frameCount);
 
+void GBASavedataRTCRead(struct GBASavedata* savedata);
+void GBASavedataRTCWrite(struct GBASavedata* savedata);
+
 struct GBASerializedState;
 void GBASavedataSerialize(const struct GBASavedata* savedata, struct GBASerializedState* state);
 void GBASavedataDeserialize(struct GBASavedata* savedata, const struct GBASerializedState* state);

include/mgba/internal/gba/serialize.h

@@ -348,7 +348,8 @@ struct GBASerializedState {
 		int32_t rtcBits;
 		int32_t rtcCommandActive;
 		RTCCommandData rtcCommand;
-		RTCControl rtcControl;
+		uint8_t rtcControl;
+		uint8_t reserved[3];
 		uint8_t time[7];
 		uint8_t devices;
 		uint16_t gyroSample;

src/gba/cart/gpio.c

@@ -100,6 +100,9 @@ void GBAHardwareInitRTC(struct GBACartridgeHardware* hw) {
 	hw->rtc.command = 0;
 	hw->rtc.control = 0x40;
 	memset(hw->rtc.time, 0, sizeof(hw->rtc.time));
+
+	hw->rtc.lastLatch = 0;
+	hw->rtc.offset = 0;
 }
 
 void _readPins(struct GBACartridgeHardware* hw) {
@@ -278,6 +281,9 @@ void _rtcUpdateClock(struct GBACartridgeHardware* hw) {
 	} else {
 		t = time(0);
 	}
+	hw->rtc.lastLatch = t;
+	t -= hw->rtc.offset;
+
 	struct tm date;
 	localtime_r(&t, &date);
 	hw->rtc.time[0] = _rtcBCD(date.tm_year - 100);

src/gba/gba.c

@@ -77,6 +77,7 @@ static void GBAInit(void* cpu, struct mCPUComponent* component) {
 	gba->memory.savedata.timing = &gba->timing;
 	gba->memory.savedata.vf = NULL;
 	gba->memory.savedata.realVf = NULL;
+	gba->memory.savedata.gpio = &gba->memory.hw;
 	GBASavedataInit(&gba->memory.savedata, NULL);
 
 	gba->video.p = gba;

src/gba/overrides.c

@@ -341,6 +341,7 @@ void GBAOverrideApply(struct GBA* gba, const struct GBACartridgeOverride* overri
 
 		if (override->hardware & HW_RTC) {
 			GBAHardwareInitRTC(&gba->memory.hw);
+			GBASavedataRTCRead(&gba->memory.savedata);
 		}
 
 		if (override->hardware & HW_GYRO) {

src/gba/savedata.c

@@ -575,6 +575,7 @@ void GBASavedataClean(struct GBASavedata* savedata, uint32_t frameCount) {
 		if (savedata->mapMode & MAP_WRITE) {
 			size_t size = GBASavedataSize(savedata);
 			if (savedata->data && savedata->vf->sync(savedata->vf, savedata->data, size)) {
+				GBASavedataRTCWrite(savedata);
 				mLOG(GBA_SAVE, INFO, "Savedata synced");
 			} else {
 				mLOG(GBA_SAVE, INFO, "Savedata failed to sync!");
@@ -583,6 +584,58 @@ void GBASavedataClean(struct GBASavedata* savedata, uint32_t frameCount) {
 	}
 }
 
+void GBASavedataRTCWrite(struct GBASavedata* savedata) {
+	if (!(savedata->gpio->devices & HW_RTC)) {
+		return;
+	}
+
+	struct GBASavedataRTCBuffer buffer;
+
+	memcpy(&buffer.time, savedata->gpio->rtc.time, 7);
+	buffer.control = savedata->gpio->rtc.control;
+	STORE_64LE(savedata->gpio->rtc.lastLatch, 0, &buffer.lastLatch);
+
+	size_t size = GBASavedataSize(savedata) & ~0xFF;
+	savedata->vf->seek(savedata->vf, size, SEEK_SET);
+	savedata->vf->write(savedata->vf, &buffer, sizeof(buffer));
+}
+
+static uint8_t _unBCD(uint8_t byte) {
+	return (byte >> 4) * 10 + (byte & 0xF);
+}
+
+void GBASavedataRTCRead(struct GBASavedata* savedata) {
+	struct GBASavedataRTCBuffer buffer;
+
+	size_t size = GBASavedataSize(savedata) & ~0xFF;
+	savedata->vf->seek(savedata->vf, size, SEEK_SET);
+	size = savedata->vf->read(savedata->vf, &buffer, sizeof(buffer));
+	if (size < sizeof(buffer)) {
+		return;
+	}
+
+	memcpy(savedata->gpio->rtc.time, &buffer.time, 7);
+
+	// Older FlashGBX sets this to 0x01 instead of the control flag.
+	// Since that bit is invalid on hardware, we can check for != 0x01
+	// to see if it's a valid value instead of just a filler value.
+	if (buffer.control != 1) {
+		savedata->gpio->rtc.control = buffer.control;
+	}
+	LOAD_64LE(savedata->gpio->rtc.lastLatch, 0, &buffer.lastLatch);
+
+	struct tm date;
+	date.tm_year = _unBCD(savedata->gpio->rtc.time[0]) + 100;
+	date.tm_mon = _unBCD(savedata->gpio->rtc.time[1]) - 1;
+	date.tm_mday = _unBCD(savedata->gpio->rtc.time[2]);
+	date.tm_hour = _unBCD(savedata->gpio->rtc.time[4]);
+	date.tm_min = _unBCD(savedata->gpio->rtc.time[5]);
+	date.tm_sec = _unBCD(savedata->gpio->rtc.time[6]);
+	date.tm_isdst = -1;
+
+	savedata->gpio->rtc.offset = savedata->gpio->rtc.lastLatch - mktime(&date);
+}
+
 void GBASavedataSerialize(const struct GBASavedata* savedata, struct GBASerializedState* state) {
 	state->savedata.type = savedata->type;
 	state->savedata.command = savedata->command;