GBA: Add somewhat more realistic flash timings, disabled currently

src/gba/gba.c

@@ -89,6 +89,9 @@ static void GBAInit(struct ARMCore* cpu, struct ARMComponent* component) {
 	gba->lastJump = 0;
 	gba->idleDetectionStep = 0;
 	gba->idleDetectionFailures = 0;
+
+	gba->realisticTiming = false;
+
 	gba->performingDMA = false;
 }
 

src/gba/gba.h

@@ -161,6 +161,8 @@ struct GBA {
 	int idleDetectionFailures;
 	int32_t cachedRegisters[16];
 	bool taintedRegisters[16];
+
+	bool realisticTiming;
 };
 
 struct GBACartridge {

src/gba/memory.c

@@ -778,7 +778,7 @@ void GBAStore8(struct ARMCore* cpu, uint32_t address, int8_t value, int* cycleCo
 		if (memory->savedata.type == SAVEDATA_AUTODETECT) {
 			if (address == SAVEDATA_FLASH_BASE) {
 				GBALog(gba, GBA_LOG_INFO, "Detected Flash savegame");
-				GBASavedataInitFlash(&memory->savedata);
+				GBASavedataInitFlash(&memory->savedata, gba->realisticTiming);
 			} else {
 				GBALog(gba, GBA_LOG_INFO, "Detected SRAM savegame");
 				GBASavedataInitSRAM(&memory->savedata);

src/gba/savedata.c

@@ -14,6 +14,8 @@
 #include <errno.h>
 #include <fcntl.h>
 
+#define FLASH_SETTLE_CYCLES 18000
+
 static void _flashSwitchBank(struct GBASavedata* savedata, int bank);
 static void _flashErase(struct GBASavedata* savedata);
 static void _flashEraseSector(struct GBASavedata* savedata, uint16_t sectorStart);
@@ -113,7 +115,7 @@ bool GBASavedataClone(struct GBASavedata* savedata, struct VFile* out) {
 	return true;
 }
 
-void GBASavedataForceType(struct GBASavedata* savedata, enum SavedataType type) {
+void GBASavedataForceType(struct GBASavedata* savedata, enum SavedataType type, bool realisticTiming) {
 	if (savedata->type != SAVEDATA_AUTODETECT) {
 		struct VFile* vf = savedata->vf;
 		GBASavedataDeinit(savedata);
@@ -123,7 +125,7 @@ void GBASavedataForceType(struct GBASavedata* savedata, enum SavedataType type)
 	case SAVEDATA_FLASH512:
 	case SAVEDATA_FLASH1M:
 		savedata->type = type;
-		GBASavedataInitFlash(savedata);
+		GBASavedataInitFlash(savedata, realisticTiming);
 		break;
 	case SAVEDATA_EEPROM:
 		GBASavedataInitEEPROM(savedata);
@@ -139,7 +141,7 @@ void GBASavedataForceType(struct GBASavedata* savedata, enum SavedataType type)
 	}
 }
 
-void GBASavedataInitFlash(struct GBASavedata* savedata) {
+void GBASavedataInitFlash(struct GBASavedata* savedata, bool realisticTiming) {
 	if (savedata->type == SAVEDATA_AUTODETECT) {
 		savedata->type = SAVEDATA_FLASH512;
 	}
@@ -162,6 +164,8 @@ void GBASavedataInitFlash(struct GBASavedata* savedata) {
 	}
 
 	savedata->currentBank = savedata->data;
+	savedata->dust = 0;
+	savedata->realisticTiming = realisticTiming;
 	if (end < SIZE_CART_FLASH512) {
 		memset(&savedata->data[end], 0xFF, flashSize - end);
 	}
@@ -226,6 +230,10 @@ uint8_t GBASavedataReadFlash(struct GBASavedata* savedata, uint16_t address) {
 			}
 		}
 	}
+	if (savedata->dust > 0 && (address >> 12) == savedata->settling) {
+		--savedata->dust;
+		return 0x5F;
+	}
 	return savedata->currentBank[address];
 }
 
@@ -384,6 +392,8 @@ void GBASavedataSerialize(const struct GBASavedata* savedata, struct GBASerializ
 	state->savedata.readBitsRemaining = savedata->readBitsRemaining;
 	state->savedata.readAddress = savedata->readAddress;
 	state->savedata.writeAddress = savedata->writeAddress;
+	state->savedata.settlingSector = savedata->settling;
+	state->savedata.settlingDust = savedata->dust;
 
 	UNUSED(includeData); // TODO
 }
@@ -393,13 +403,16 @@ void GBASavedataDeserialize(struct GBASavedata* savedata, const struct GBASerial
 		return;
 	}
 	if (savedata->type != state->savedata.type) {
-		GBASavedataForceType(savedata, state->savedata.type);
+		GBASavedataForceType(savedata, state->savedata.type, savedata->realisticTiming);
 	}
 	savedata->command = state->savedata.command;
 	savedata->flashState = state->savedata.flashState;
 	savedata->readBitsRemaining = state->savedata.readBitsRemaining;
 	savedata->readAddress = state->savedata.readAddress;
 	savedata->writeAddress = state->savedata.writeAddress;
+	savedata->settling = state->savedata.settlingSector;
+	savedata->dust = state->savedata.settlingDust;
+
 	if (savedata->type == SAVEDATA_FLASH1M) {
 		_flashSwitchBank(savedata, state->savedata.flashBank);
 	}
@@ -434,5 +447,9 @@ void _flashEraseSector(struct GBASavedata* savedata, uint16_t sectorStart) {
 	if (savedata->type == SAVEDATA_FLASH1M) {
 		GBALog(0, GBA_LOG_DEBUG, "Performing unknown sector-size erase at 0x%04x", sectorStart);
 	}
+	savedata->settling = sectorStart >> 12;
+	if (savedata->realisticTiming) {
+		savedata->dust = FLASH_SETTLE_CYCLES;
+	}
 	memset(&savedata->currentBank[sectorStart & ~(size - 1)], 0xFF, size);
 }

src/gba/savedata.h

@@ -73,6 +73,10 @@ struct GBASavedata {
 
 	uint8_t* currentBank;
 
+	bool realisticTiming;
+	unsigned settling;
+	int dust;
+
 	enum FlashStateMachine flashState;
 };
 
@@ -82,9 +86,9 @@ void GBASavedataDeinit(struct GBASavedata* savedata);
 void GBASavedataMask(struct GBASavedata* savedata, struct VFile* vf);
 void GBASavedataUnmask(struct GBASavedata* savedata);
 bool GBASavedataClone(struct GBASavedata* savedata, struct VFile* out);
-void GBASavedataForceType(struct GBASavedata* savedata, enum SavedataType type);
+void GBASavedataForceType(struct GBASavedata* savedata, enum SavedataType type, bool realisticTiming);
 
-void GBASavedataInitFlash(struct GBASavedata* savedata);
+void GBASavedataInitFlash(struct GBASavedata* savedata, bool realisticTiming);
 void GBASavedataInitEEPROM(struct GBASavedata* savedata);
 void GBASavedataInitSRAM(struct GBASavedata* savedata);
 

src/gba/serialize.h

@@ -162,8 +162,9 @@ extern const uint32_t GBA_SAVESTATE_MAGIC;
  * | 0x002E3 - 0x002E3: Reserved
  * | 0x002E4 - 0x002E7: EEPROM read bits remaining
  * | 0x002E8 - 0x002EB: EEPROM read address
- * | 0x002EC - 0x002EBF EEPROM write address
+ * | 0x002EC - 0x002EF: EEPROM write address
- * 0x002F0 - 0x002F3: Reserved (leave zero)
+ * | 0x002F0 - 0x002F1: Flash settling sector
+ * | 0x002F2 - 0x002F3: Flash settling remaining
  * 0x002F4 - 0x002FF: Prefetch
  * | 0x002F4 - 0x002F7: GBA BIOS bus prefetch
  * | 0x002F8 - 0x002FB: CPU prefecth (decode slot)
@@ -297,10 +298,10 @@ struct GBASerializedState {
 		int32_t readBitsRemaining;
 		uint32_t readAddress;
 		uint32_t writeAddress;
+		uint16_t settlingSector;
+		uint16_t settlingDust;
 	} savedata;
 
-	uint32_t reservedPadding;
-
 	uint32_t biosPrefetch;
 	uint32_t cpuPrefetch[2];
 

src/gba/supervisor/overrides.c

@@ -249,7 +249,7 @@ void GBAOverrideSave(struct Configuration* config, const struct GBACartridgeOver
 
 void GBAOverrideApply(struct GBA* gba, const struct GBACartridgeOverride* override) {
 	if (override->savetype != SAVEDATA_AUTODETECT) {
-		GBASavedataForceType(&gba->memory.savedata, override->savetype);
+		GBASavedataForceType(&gba->memory.savedata, override->savetype, gba->realisticTiming);
 	}
 
 	if (override->hardware != HW_NO_OVERRIDE) {