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mGBA Game Boy Advance Emulator

src/gb/mbc.c (view raw)

   1/* Copyright (c) 2013-2016 Jeffrey Pfau
   2 *
   3 * This Source Code Form is subject to the terms of the Mozilla Public
   4 * License, v. 2.0. If a copy of the MPL was not distributed with this
   5 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   6#include <mgba/internal/gb/mbc.h>
   7
   8#include <mgba/core/interface.h>
   9#include <mgba/internal/lr35902/lr35902.h>
  10#include <mgba/internal/gb/gb.h>
  11#include <mgba/internal/gb/memory.h>
  12#include <mgba-util/crc32.h>
  13#include <mgba-util/vfs.h>
  14
  15const uint32_t GB_LOGO_HASH = 0x46195417;
  16
  17mLOG_DEFINE_CATEGORY(GB_MBC, "GB MBC", "gb.mbc");
  18
  19static void _GBMBCNone(struct GB* gb, uint16_t address, uint8_t value) {
  20	UNUSED(gb);
  21	UNUSED(address);
  22	UNUSED(value);
  23
  24	mLOG(GB_MBC, GAME_ERROR, "Wrote to invalid MBC");
  25}
  26
  27static void _GBMBC1(struct GB*, uint16_t address, uint8_t value);
  28static void _GBMBC2(struct GB*, uint16_t address, uint8_t value);
  29static void _GBMBC3(struct GB*, uint16_t address, uint8_t value);
  30static void _GBMBC5(struct GB*, uint16_t address, uint8_t value);
  31static void _GBMBC6(struct GB*, uint16_t address, uint8_t value);
  32static void _GBMBC7(struct GB*, uint16_t address, uint8_t value);
  33static void _GBMMM01(struct GB*, uint16_t address, uint8_t value);
  34static void _GBHuC1(struct GB*, uint16_t address, uint8_t value);
  35static void _GBHuC3(struct GB*, uint16_t address, uint8_t value);
  36static void _GBPocketCam(struct GB* gb, uint16_t address, uint8_t value);
  37static void _GBTAMA5(struct GB* gb, uint16_t address, uint8_t value);
  38
  39static uint8_t _GBMBC2Read(struct GBMemory*, uint16_t address);
  40static uint8_t _GBMBC6Read(struct GBMemory*, uint16_t address);
  41static uint8_t _GBMBC7Read(struct GBMemory*, uint16_t address);
  42static void _GBMBC7Write(struct GBMemory* memory, uint16_t address, uint8_t value);
  43
  44static uint8_t _GBTAMA5Read(struct GBMemory*, uint16_t address);
  45
  46static uint8_t _GBPocketCamRead(struct GBMemory*, uint16_t address);
  47static void _GBPocketCamCapture(struct GBMemory*);
  48
  49void GBMBCSwitchBank(struct GB* gb, int bank) {
  50	size_t bankStart = bank * GB_SIZE_CART_BANK0;
  51	if (bankStart + GB_SIZE_CART_BANK0 > gb->memory.romSize) {
  52		mLOG(GB_MBC, GAME_ERROR, "Attempting to switch to an invalid ROM bank: %0X", bank);
  53		bankStart &= (gb->memory.romSize - 1);
  54		bank = bankStart / GB_SIZE_CART_BANK0;
  55	}
  56	gb->memory.romBank = &gb->memory.rom[bankStart];
  57	gb->memory.currentBank = bank;
  58	if (gb->cpu->pc < GB_BASE_VRAM) {
  59		gb->cpu->memory.setActiveRegion(gb->cpu, gb->cpu->pc);
  60	}
  61}
  62
  63void GBMBCSwitchBank0(struct GB* gb, int bank) {
  64	size_t bankStart = bank * GB_SIZE_CART_BANK0;
  65	if (bankStart + GB_SIZE_CART_BANK0 > gb->memory.romSize) {
  66		mLOG(GB_MBC, GAME_ERROR, "Attempting to switch to an invalid ROM bank: %0X", bank);
  67		bankStart &= (gb->memory.romSize - 1);
  68	}
  69	gb->memory.romBase = &gb->memory.rom[bankStart];
  70	if (gb->cpu->pc < GB_SIZE_CART_BANK0) {
  71		gb->cpu->memory.setActiveRegion(gb->cpu, gb->cpu->pc);
  72	}
  73}
  74
  75void GBMBCSwitchHalfBank(struct GB* gb, int half, int bank) {
  76	size_t bankStart = bank * GB_SIZE_CART_HALFBANK;
  77	if (bankStart + GB_SIZE_CART_HALFBANK > gb->memory.romSize) {
  78		mLOG(GB_MBC, GAME_ERROR, "Attempting to switch to an invalid ROM bank: %0X", bank);
  79		bankStart &= (gb->memory.romSize - 1);
  80		bank = bankStart / GB_SIZE_CART_HALFBANK;
  81		if (!bank) {
  82			++bank;
  83		}
  84	}
  85	if (!half) {
  86		gb->memory.romBank = &gb->memory.rom[bankStart];
  87		gb->memory.currentBank = bank;
  88	} else {
  89		gb->memory.mbcState.mbc6.romBank1 = &gb->memory.rom[bankStart];
  90		gb->memory.mbcState.mbc6.currentBank1 = bank;
  91	}
  92	if (gb->cpu->pc < GB_BASE_VRAM) {
  93		gb->cpu->memory.setActiveRegion(gb->cpu, gb->cpu->pc);
  94	}
  95}
  96
  97static bool _isMulticart(const uint8_t* mem) {
  98	bool success = true;
  99	struct VFile* vf;
 100
 101	vf = VFileFromConstMemory(&mem[GB_SIZE_CART_BANK0 * 0x10], 1024);
 102	success = success && GBIsROM(vf);
 103	vf->close(vf);
 104
 105	vf = VFileFromConstMemory(&mem[GB_SIZE_CART_BANK0 * 0x20], 1024);
 106	success = success && GBIsROM(vf);
 107	vf->close(vf);
 108
 109	return success;
 110}
 111
 112void GBMBCSwitchSramBank(struct GB* gb, int bank) {
 113	size_t bankStart = bank * GB_SIZE_EXTERNAL_RAM;
 114	if (bankStart + GB_SIZE_EXTERNAL_RAM > gb->sramSize) {
 115		mLOG(GB_MBC, GAME_ERROR, "Attempting to switch to an invalid RAM bank: %0X", bank);
 116		bankStart &= (gb->sramSize - 1);
 117		bank = bankStart / GB_SIZE_EXTERNAL_RAM;
 118	}
 119	gb->memory.sramBank = &gb->memory.sram[bankStart];
 120	gb->memory.sramCurrentBank = bank;
 121}
 122
 123void GBMBCSwitchSramHalfBank(struct GB* gb, int half, int bank) {
 124	size_t bankStart = bank * GB_SIZE_EXTERNAL_RAM_HALFBANK;
 125	if (bankStart + GB_SIZE_EXTERNAL_RAM_HALFBANK > gb->sramSize) {
 126		mLOG(GB_MBC, GAME_ERROR, "Attempting to switch to an invalid RAM bank: %0X", bank);
 127		bankStart &= (gb->sramSize - 1);
 128		bank = bankStart / GB_SIZE_EXTERNAL_RAM_HALFBANK;
 129	}
 130	if (!half) {
 131		gb->memory.sramBank = &gb->memory.sram[bankStart];
 132		gb->memory.sramCurrentBank = bank;
 133	} else {
 134		gb->memory.mbcState.mbc6.sramBank1 = &gb->memory.sram[bankStart];
 135		gb->memory.mbcState.mbc6.currentSramBank1 = bank;
 136	}
 137}
 138
 139void GBMBCInit(struct GB* gb) {
 140	const struct GBCartridge* cart = (const struct GBCartridge*) &gb->memory.rom[0x100];
 141	if (gb->memory.rom) {
 142		if (gb->memory.romSize >= 0x8000) {
 143			const struct GBCartridge* cartFooter = (const struct GBCartridge*) &gb->memory.rom[gb->memory.romSize - 0x7F00];
 144			if (doCrc32(cartFooter->logo, sizeof(cartFooter->logo)) == GB_LOGO_HASH && cartFooter->type >= 0x0B && cartFooter->type <= 0x0D) {
 145				cart = cartFooter;
 146			}
 147		}
 148		switch (cart->ramSize) {
 149		case 0:
 150			gb->sramSize = 0;
 151			break;
 152		case 1:
 153			gb->sramSize = 0x800;
 154			break;
 155		default:
 156		case 2:
 157			gb->sramSize = 0x2000;
 158			break;
 159		case 3:
 160			gb->sramSize = 0x8000;
 161			break;
 162		case 4:
 163			gb->sramSize = 0x20000;
 164			break;
 165		case 5:
 166			gb->sramSize = 0x10000;
 167			break;
 168		}
 169
 170		if (gb->memory.mbcType == GB_MBC_AUTODETECT) {
 171			switch (cart->type) {
 172			case 0:
 173			case 8:
 174			case 9:
 175				gb->memory.mbcType = GB_MBC_NONE;
 176				break;
 177			case 1:
 178			case 2:
 179			case 3:
 180				gb->memory.mbcType = GB_MBC1;
 181				if (gb->memory.romSize >= GB_SIZE_CART_BANK0 * 0x31 && _isMulticart(gb->memory.rom)) {
 182					gb->memory.mbcState.mbc1.multicartStride = 4;
 183				} else {
 184					gb->memory.mbcState.mbc1.multicartStride = 5;
 185				}
 186				break;
 187			case 5:
 188			case 6:
 189				gb->memory.mbcType = GB_MBC2;
 190				break;
 191			case 0x0B:
 192			case 0x0C:
 193			case 0x0D:
 194				gb->memory.mbcType = GB_MMM01;
 195				break;
 196			case 0x0F:
 197			case 0x10:
 198				gb->memory.mbcType = GB_MBC3_RTC;
 199				break;
 200			case 0x11:
 201			case 0x12:
 202			case 0x13:
 203				gb->memory.mbcType = GB_MBC3;
 204				break;
 205			default:
 206				mLOG(GB_MBC, WARN, "Unknown MBC type: %02X", cart->type);
 207				// Fall through
 208			case 0x19:
 209			case 0x1A:
 210			case 0x1B:
 211				gb->memory.mbcType = GB_MBC5;
 212				break;
 213			case 0x1C:
 214			case 0x1D:
 215			case 0x1E:
 216				gb->memory.mbcType = GB_MBC5_RUMBLE;
 217				break;
 218			case 0x20:
 219				gb->memory.mbcType = GB_MBC6;
 220				break;
 221			case 0x22:
 222				gb->memory.mbcType = GB_MBC7;
 223				break;
 224			case 0xFC:
 225				gb->memory.mbcType = GB_POCKETCAM;
 226				break;
 227			case 0xFD:
 228				gb->memory.mbcType = GB_TAMA5;
 229				break;
 230			case 0xFE:
 231				gb->memory.mbcType = GB_HuC3;
 232				break;
 233			case 0xFF:
 234				gb->memory.mbcType = GB_HuC1;
 235				break;
 236			}
 237		}
 238	} else {
 239		gb->memory.mbcType = GB_MBC_NONE;
 240	}
 241	gb->memory.mbcRead = NULL;
 242	switch (gb->memory.mbcType) {
 243	case GB_MBC_NONE:
 244		gb->memory.mbcWrite = _GBMBCNone;
 245		break;
 246	case GB_MBC1:
 247		gb->memory.mbcWrite = _GBMBC1;
 248		break;
 249	case GB_MBC2:
 250		gb->memory.mbcWrite = _GBMBC2;
 251		gb->memory.mbcRead = _GBMBC2Read;
 252		gb->sramSize = 0x100;
 253		break;
 254	case GB_MBC3:
 255		gb->memory.mbcWrite = _GBMBC3;
 256		break;
 257	default:
 258		mLOG(GB_MBC, WARN, "Unknown MBC type: %02X", cart->type);
 259		// Fall through
 260	case GB_MBC5:
 261		gb->memory.mbcWrite = _GBMBC5;
 262		break;
 263	case GB_MBC6:
 264		mLOG(GB_MBC, WARN, "unimplemented MBC: MBC6");
 265		gb->memory.mbcWrite = _GBMBC6;
 266		gb->memory.mbcRead = _GBMBC6Read;
 267		break;
 268	case GB_MBC7:
 269		gb->memory.mbcWrite = _GBMBC7;
 270		gb->memory.mbcRead = _GBMBC7Read;
 271		gb->sramSize = 0x100;
 272		break;
 273	case GB_MMM01:
 274		gb->memory.mbcWrite = _GBMMM01;
 275		break;
 276	case GB_HuC1:
 277		gb->memory.mbcWrite = _GBHuC1;
 278		break;
 279	case GB_HuC3:
 280		gb->memory.mbcWrite = _GBHuC3;
 281		break;
 282	case GB_TAMA5:
 283		mLOG(GB_MBC, WARN, "unimplemented MBC: TAMA5");
 284		memset(gb->memory.rtcRegs, 0, sizeof(gb->memory.rtcRegs));
 285		gb->memory.mbcWrite = _GBTAMA5;
 286		gb->memory.mbcRead = _GBTAMA5Read;
 287		gb->sramSize = 0x20;
 288		break;
 289	case GB_MBC3_RTC:
 290		memset(gb->memory.rtcRegs, 0, sizeof(gb->memory.rtcRegs));
 291		gb->memory.mbcWrite = _GBMBC3;
 292		break;
 293	case GB_MBC5_RUMBLE:
 294		gb->memory.mbcWrite = _GBMBC5;
 295		break;
 296	case GB_POCKETCAM:
 297		gb->memory.mbcWrite = _GBPocketCam;
 298		gb->memory.mbcRead = _GBPocketCamRead;
 299		if (gb->memory.cam && gb->memory.cam->startRequestImage) {
 300			gb->memory.cam->startRequestImage(gb->memory.cam, GBCAM_WIDTH, GBCAM_HEIGHT, mCOLOR_ANY);
 301		}
 302		break;
 303	}
 304
 305	gb->memory.currentBank = 1;
 306	gb->memory.sramCurrentBank = 0;
 307	gb->memory.sramAccess = false;
 308	gb->memory.rtcAccess = false;
 309	gb->memory.activeRtcReg = 0;
 310	gb->memory.rtcLatched = false;
 311	gb->memory.rtcLastLatch = 0;
 312	if (gb->memory.rtc) {
 313		if (gb->memory.rtc->sample) {
 314			gb->memory.rtc->sample(gb->memory.rtc);
 315		}
 316		gb->memory.rtcLastLatch = gb->memory.rtc->unixTime(gb->memory.rtc);
 317	} else {
 318		gb->memory.rtcLastLatch = time(0);
 319	}
 320	memset(&gb->memory.rtcRegs, 0, sizeof(gb->memory.rtcRegs));
 321
 322	GBResizeSram(gb, gb->sramSize);
 323
 324	if (gb->memory.mbcType == GB_MBC3_RTC) {
 325		GBMBCRTCRead(gb);
 326	}
 327}
 328
 329static void _latchRtc(struct mRTCSource* rtc, uint8_t* rtcRegs, time_t* rtcLastLatch) {
 330	time_t t;
 331	if (rtc) {
 332		if (rtc->sample) {
 333			rtc->sample(rtc);
 334		}
 335		t = rtc->unixTime(rtc);
 336	} else {
 337		t = time(0);
 338	}
 339	time_t currentLatch = t;
 340	t -= *rtcLastLatch;
 341	*rtcLastLatch = currentLatch;
 342
 343	int64_t diff;
 344	diff = rtcRegs[0] + t % 60;
 345	if (diff < 0) {
 346		diff += 60;
 347		t -= 60;
 348	}
 349	rtcRegs[0] = diff % 60;
 350	t /= 60;
 351	t += diff / 60;
 352
 353	diff = rtcRegs[1] + t % 60;
 354	if (diff < 0) {
 355		diff += 60;
 356		t -= 60;
 357	}
 358	rtcRegs[1] = diff % 60;
 359	t /= 60;
 360	t += diff / 60;
 361
 362	diff = rtcRegs[2] + t % 24;
 363	if (diff < 0) {
 364		diff += 24;
 365		t -= 24;
 366	}
 367	rtcRegs[2] = diff % 24;
 368	t /= 24;
 369	t += diff / 24;
 370
 371	diff = rtcRegs[3] + ((rtcRegs[4] & 1) << 8) + (t & 0x1FF);
 372	rtcRegs[3] = diff;
 373	rtcRegs[4] &= 0xFE;
 374	rtcRegs[4] |= (diff >> 8) & 1;
 375	if (diff & 0x200) {
 376		rtcRegs[4] |= 0x80;
 377	}
 378}
 379
 380void _GBMBC1(struct GB* gb, uint16_t address, uint8_t value) {
 381	struct GBMemory* memory = &gb->memory;
 382	int bank = value & 0x1F;
 383	int stride = 1 << memory->mbcState.mbc1.multicartStride;
 384	switch (address >> 13) {
 385	case 0x0:
 386		switch (value) {
 387		case 0:
 388			memory->sramAccess = false;
 389			break;
 390		case 0xA:
 391			memory->sramAccess = true;
 392			GBMBCSwitchSramBank(gb, memory->sramCurrentBank);
 393			break;
 394		default:
 395			// TODO
 396			mLOG(GB_MBC, STUB, "MBC1 unknown value %02X", value);
 397			break;
 398		}
 399		break;
 400	case 0x1:
 401		if (!bank) {
 402			++bank;
 403		}
 404		bank &= stride - 1;
 405		GBMBCSwitchBank(gb, bank | (memory->currentBank & (3 * stride)));
 406		break;
 407	case 0x2:
 408		bank &= 3;
 409		if (memory->mbcState.mbc1.mode) {
 410			GBMBCSwitchBank0(gb, bank << gb->memory.mbcState.mbc1.multicartStride);
 411			GBMBCSwitchSramBank(gb, bank);
 412		}
 413		GBMBCSwitchBank(gb, (bank << memory->mbcState.mbc1.multicartStride) | (memory->currentBank & (stride - 1)));
 414		break;
 415	case 0x3:
 416		memory->mbcState.mbc1.mode = value & 1;
 417		if (memory->mbcState.mbc1.mode) {
 418			GBMBCSwitchBank0(gb, memory->currentBank & ~((1 << memory->mbcState.mbc1.multicartStride) - 1));
 419		} else {
 420			GBMBCSwitchBank0(gb, 0);
 421			GBMBCSwitchSramBank(gb, 0);
 422		}
 423		break;
 424	default:
 425		// TODO
 426		mLOG(GB_MBC, STUB, "MBC1 unknown address: %04X:%02X", address, value);
 427		break;
 428	}
 429}
 430
 431void _GBMBC2(struct GB* gb, uint16_t address, uint8_t value) {
 432	struct GBMemory* memory = &gb->memory;
 433	int shift = (address & 1) * 4;
 434	int bank = value & 0xF;
 435	switch (address >> 13) {
 436	case 0x0:
 437		switch (value) {
 438		case 0:
 439			memory->sramAccess = false;
 440			break;
 441		case 0xA:
 442			memory->sramAccess = true;
 443			break;
 444		default:
 445			// TODO
 446			mLOG(GB_MBC, STUB, "MBC1 unknown value %02X", value);
 447			break;
 448		}
 449		break;
 450	case 0x1:
 451		if (!bank) {
 452			++bank;
 453		}
 454		GBMBCSwitchBank(gb, bank);
 455		break;
 456	case 0x5:
 457		if (!memory->sramAccess) {
 458			return;
 459		}
 460		address &= 0x1FF;
 461		memory->sramBank[(address >> 1)] &= 0xF0 >> shift;
 462		memory->sramBank[(address >> 1)] |= (value & 0xF) << shift;
 463		break;
 464	default:
 465		// TODO
 466		mLOG(GB_MBC, STUB, "MBC2 unknown address: %04X:%02X", address, value);
 467		break;
 468	}
 469}
 470
 471static uint8_t _GBMBC2Read(struct GBMemory* memory, uint16_t address) {
 472	address &= 0x1FF;
 473	int shift = (address & 1) * 4;
 474	return (memory->sramBank[(address >> 1)] >> shift) | 0xF0;
 475}
 476
 477void _GBMBC3(struct GB* gb, uint16_t address, uint8_t value) {
 478	struct GBMemory* memory = &gb->memory;
 479	int bank = value & 0x7F;
 480	switch (address >> 13) {
 481	case 0x0:
 482		switch (value) {
 483		case 0:
 484			memory->sramAccess = false;
 485			break;
 486		case 0xA:
 487			memory->sramAccess = true;
 488			GBMBCSwitchSramBank(gb, memory->sramCurrentBank);
 489			break;
 490		default:
 491			// TODO
 492			mLOG(GB_MBC, STUB, "MBC3 unknown value %02X", value);
 493			break;
 494		}
 495		break;
 496	case 0x1:
 497		if (!bank) {
 498			++bank;
 499		}
 500		GBMBCSwitchBank(gb, bank);
 501		break;
 502	case 0x2:
 503		if (value < 4) {
 504			GBMBCSwitchSramBank(gb, value);
 505			memory->rtcAccess = false;
 506		} else if (value >= 8 && value <= 0xC) {
 507			memory->activeRtcReg = value - 8;
 508			memory->rtcAccess = true;
 509		}
 510		break;
 511	case 0x3:
 512		if (memory->rtcLatched && value == 0) {
 513			memory->rtcLatched = false;
 514		} else if (!memory->rtcLatched && value == 1) {
 515			_latchRtc(gb->memory.rtc, gb->memory.rtcRegs, &gb->memory.rtcLastLatch);
 516			memory->rtcLatched = true;
 517		}
 518		break;
 519	}
 520}
 521
 522void _GBMBC5(struct GB* gb, uint16_t address, uint8_t value) {
 523	struct GBMemory* memory = &gb->memory;
 524	int bank;
 525	switch (address >> 12) {
 526	case 0x0:
 527	case 0x1:
 528		switch (value) {
 529		case 0:
 530			memory->sramAccess = false;
 531			break;
 532		case 0xA:
 533			memory->sramAccess = true;
 534			GBMBCSwitchSramBank(gb, memory->sramCurrentBank);
 535			break;
 536		default:
 537			// TODO
 538			mLOG(GB_MBC, STUB, "MBC5 unknown value %02X", value);
 539			break;
 540		}
 541		break;
 542	case 0x2:
 543		bank = (memory->currentBank & 0x100) | value;
 544		GBMBCSwitchBank(gb, bank);
 545		break;
 546	case 0x3:
 547		bank = (memory->currentBank & 0xFF) | ((value & 1) << 8);
 548		GBMBCSwitchBank(gb, bank);
 549		break;
 550	case 0x4:
 551	case 0x5:
 552		if (memory->mbcType == GB_MBC5_RUMBLE && memory->rumble) {
 553			memory->rumble->setRumble(memory->rumble, (value >> 3) & 1);
 554			value &= ~8;
 555		}
 556		GBMBCSwitchSramBank(gb, value & 0xF);
 557		break;
 558	default:
 559		// TODO
 560		mLOG(GB_MBC, STUB, "MBC5 unknown address: %04X:%02X", address, value);
 561		break;
 562	}
 563}
 564
 565void _GBMBC6(struct GB* gb, uint16_t address, uint8_t value) {
 566	struct GBMemory* memory = &gb->memory;
 567	int bank = value;
 568	switch (address >> 10) {
 569	case 0:
 570		switch (value) {
 571		case 0:
 572			memory->mbcState.mbc6.sramAccess = false;
 573			break;
 574		case 0xA:
 575			memory->mbcState.mbc6.sramAccess = true;
 576			break;
 577		default:
 578			// TODO
 579			mLOG(GB_MBC, STUB, "MBC6 unknown value %02X", value);
 580			break;
 581		}
 582		break;
 583	case 0x1:
 584		GBMBCSwitchSramHalfBank(gb, 0, bank);
 585		break;
 586	case 0x2:
 587		GBMBCSwitchSramHalfBank(gb, 1, bank);
 588		break;
 589	case 0x8:
 590	case 0x9:
 591		GBMBCSwitchHalfBank(gb, 0, bank);
 592		break;
 593	case 0xC:
 594	case 0xD:
 595		GBMBCSwitchHalfBank(gb, 1, bank);
 596		break;
 597	case 0x28:
 598	case 0x29:
 599	case 0x2A:
 600	case 0x2B:
 601		if (memory->mbcState.mbc6.sramAccess) {
 602			memory->sramBank[address & (GB_SIZE_EXTERNAL_RAM_HALFBANK - 1)] = value;
 603		}
 604		break;
 605	case 0x2C:
 606	case 0x2D:
 607	case 0x2E:
 608	case 0x2F:
 609		if (memory->mbcState.mbc6.sramAccess) {
 610			memory->mbcState.mbc6.sramBank1[address & (GB_SIZE_EXTERNAL_RAM_HALFBANK - 1)] = value;
 611		}
 612		break;
 613	default:
 614		mLOG(GB_MBC, STUB, "MBC6 unknown address: %04X:%02X", address, value);
 615		break;
 616	}
 617}
 618
 619uint8_t _GBMBC6Read(struct GBMemory* memory, uint16_t address) {
 620	if (!memory->mbcState.mbc6.sramAccess) {
 621		return 0xFF;
 622	}
 623	switch (address >> 12) {
 624	case 0xA:
 625		return memory->sramBank[address & (GB_SIZE_EXTERNAL_RAM_HALFBANK - 1)];
 626	case 0xB:
 627		return memory->mbcState.mbc6.sramBank1[address & (GB_SIZE_EXTERNAL_RAM_HALFBANK - 1)];
 628	}
 629	return 0xFF;
 630}
 631
 632void _GBMBC7(struct GB* gb, uint16_t address, uint8_t value) {
 633	int bank = value & 0x7F;
 634	switch (address >> 13) {
 635	case 0x0:
 636		switch (value) {
 637		default:
 638		case 0:
 639			gb->memory.mbcState.mbc7.access = 0;
 640			break;
 641		case 0xA:
 642			gb->memory.mbcState.mbc7.access |= 1;
 643			break;
 644		}
 645		break;
 646	case 0x1:
 647		GBMBCSwitchBank(gb, bank);
 648		break;
 649	case 0x2:
 650		if (value == 0x40) {
 651			gb->memory.mbcState.mbc7.access |= 2;
 652		} else {
 653			gb->memory.mbcState.mbc7.access &= ~2;
 654		}
 655		break;
 656	case 0x5:
 657		_GBMBC7Write(&gb->memory, address, value);
 658		break;
 659	default:
 660		// TODO
 661		mLOG(GB_MBC, STUB, "MBC7 unknown address: %04X:%02X", address, value);
 662		break;
 663	}
 664}
 665
 666uint8_t _GBMBC7Read(struct GBMemory* memory, uint16_t address) {
 667	struct GBMBC7State* mbc7 = &memory->mbcState.mbc7;
 668	if (mbc7->access != 3) {
 669		return 0xFF;
 670	}
 671	switch (address & 0xF0) {
 672	case 0x20:
 673		if (memory->rotation && memory->rotation->readTiltX) {
 674			int32_t x = -memory->rotation->readTiltX(memory->rotation);
 675			x >>= 21;
 676			x += 0x81D0;
 677			return x;
 678		}
 679		return 0xFF;
 680	case 0x30:
 681		if (memory->rotation && memory->rotation->readTiltX) {
 682			int32_t x = -memory->rotation->readTiltX(memory->rotation);
 683			x >>= 21;
 684			x += 0x81D0;
 685			return x >> 8;
 686		}
 687		return 7;
 688	case 0x40:
 689		if (memory->rotation && memory->rotation->readTiltY) {
 690			int32_t y = -memory->rotation->readTiltY(memory->rotation);
 691			y >>= 21;
 692			y += 0x81D0;
 693			return y;
 694		}
 695		return 0xFF;
 696	case 0x50:
 697		if (memory->rotation && memory->rotation->readTiltY) {
 698			int32_t y = -memory->rotation->readTiltY(memory->rotation);
 699			y >>= 21;
 700			y += 0x81D0;
 701			return y >> 8;
 702		}
 703		return 7;
 704	case 0x60:
 705		return 0;
 706	case 0x80:
 707		return mbc7->eeprom;
 708	default:
 709		return 0xFF;
 710	}
 711}
 712
 713static void _GBMBC7Write(struct GBMemory* memory, uint16_t address, uint8_t value) {
 714	struct GBMBC7State* mbc7 = &memory->mbcState.mbc7;
 715	if (mbc7->access != 3) {
 716		return;
 717	}
 718	switch (address & 0xF0) {
 719	case 0x00:
 720		mbc7->latch = (value & 0x55) == 0x55;
 721		return;
 722	case 0x10:
 723		mbc7->latch |= (value & 0xAA);
 724		if (mbc7->latch == 0xAB && memory->rotation && memory->rotation->sample) {
 725			memory->rotation->sample(memory->rotation);
 726		}
 727		mbc7->latch = 0;
 728		return;
 729	default:
 730		mLOG(GB_MBC, STUB, "MBC7 unknown register: %04X:%02X", address, value);
 731		return;
 732	case 0x80:
 733		break;
 734	}
 735	GBMBC7Field old = memory->mbcState.mbc7.eeprom;
 736	value = GBMBC7FieldFillDO(value); // Hi-Z
 737	if (!GBMBC7FieldIsCS(old) && GBMBC7FieldIsCS(value)) {
 738		mbc7->state = GBMBC7_STATE_IDLE;
 739	}
 740	if (!GBMBC7FieldIsCLK(old) && GBMBC7FieldIsCLK(value)) {
 741		if (mbc7->state == GBMBC7_STATE_READ_COMMAND || mbc7->state == GBMBC7_STATE_EEPROM_WRITE || mbc7->state == GBMBC7_STATE_EEPROM_WRAL) {
 742			mbc7->sr <<= 1;
 743			mbc7->sr |= GBMBC7FieldGetDI(value);
 744			++mbc7->srBits;
 745		}
 746		switch (mbc7->state) {
 747		case GBMBC7_STATE_IDLE:
 748			if (GBMBC7FieldIsDI(value)) {
 749				mbc7->state = GBMBC7_STATE_READ_COMMAND;
 750				mbc7->srBits = 0;
 751				mbc7->sr = 0;
 752			}
 753			break;
 754		case GBMBC7_STATE_READ_COMMAND:
 755			if (mbc7->srBits == 10) {
 756				mbc7->state = 0x10 | (mbc7->sr >> 6);
 757				if (mbc7->state & 0xC) {
 758					mbc7->state &= ~0x3;
 759				}
 760				mbc7->srBits = 0;
 761				mbc7->address = mbc7->sr & 0x7F;
 762			}
 763			break;
 764		case GBMBC7_STATE_DO:
 765			value = GBMBC7FieldSetDO(value, mbc7->sr >> 15);
 766			mbc7->sr <<= 1;
 767			--mbc7->srBits;
 768			if (!mbc7->srBits) {
 769				mbc7->state = GBMBC7_STATE_IDLE;
 770			}
 771			break;
 772		default:
 773			break;
 774		}
 775		switch (mbc7->state) {
 776		case GBMBC7_STATE_EEPROM_EWEN:
 777			mbc7->writable = true;
 778			mbc7->state = GBMBC7_STATE_IDLE;
 779			break;
 780		case GBMBC7_STATE_EEPROM_EWDS:
 781			mbc7->writable = false;
 782			mbc7->state = GBMBC7_STATE_IDLE;
 783			break;
 784		case GBMBC7_STATE_EEPROM_WRITE:
 785			if (mbc7->srBits == 16) {
 786				if (mbc7->writable) {
 787					memory->sram[mbc7->address * 2] = mbc7->sr >> 8;
 788					memory->sram[mbc7->address * 2 + 1] = mbc7->sr;
 789				}
 790				mbc7->state = GBMBC7_STATE_IDLE;
 791			}
 792			break;
 793		case GBMBC7_STATE_EEPROM_ERASE:
 794			if (mbc7->writable) {
 795				memory->sram[mbc7->address * 2] = 0xFF;
 796				memory->sram[mbc7->address * 2 + 1] = 0xFF;
 797			}
 798			mbc7->state = GBMBC7_STATE_IDLE;
 799			break;
 800		case GBMBC7_STATE_EEPROM_READ:
 801			mbc7->srBits = 16;
 802			mbc7->sr = memory->sram[mbc7->address * 2] << 8;
 803			mbc7->sr |= memory->sram[mbc7->address * 2 + 1];
 804			mbc7->state = GBMBC7_STATE_DO;
 805			value = GBMBC7FieldClearDO(value);
 806			break;
 807		case GBMBC7_STATE_EEPROM_WRAL:
 808			if (mbc7->srBits == 16) {
 809				if (mbc7->writable) {
 810					int i;
 811					for (i = 0; i < 128; ++i) {
 812						memory->sram[i * 2] = mbc7->sr >> 8;
 813						memory->sram[i * 2 + 1] = mbc7->sr;
 814					}
 815				}
 816				mbc7->state = GBMBC7_STATE_IDLE;
 817			}
 818			break;
 819		case GBMBC7_STATE_EEPROM_ERAL:
 820			if (mbc7->writable) {
 821				int i;
 822				for (i = 0; i < 128; ++i) {
 823					memory->sram[i * 2] = 0xFF;
 824					memory->sram[i * 2 + 1] = 0xFF;
 825				}
 826			}
 827			mbc7->state = GBMBC7_STATE_IDLE;
 828			break;
 829		default:
 830			break;
 831		}
 832	} else if (GBMBC7FieldIsCS(value) && GBMBC7FieldIsCLK(old) && !GBMBC7FieldIsCLK(value)) {
 833		value = GBMBC7FieldSetDO(value, GBMBC7FieldGetDO(old));
 834	}
 835	mbc7->eeprom = value;
 836}
 837
 838void _GBMMM01(struct GB* gb, uint16_t address, uint8_t value) {
 839	struct GBMemory* memory = &gb->memory;
 840	if (!memory->mbcState.mmm01.locked) {
 841		switch (address >> 13) {
 842		case 0x0:
 843			memory->mbcState.mmm01.locked = true;
 844			GBMBCSwitchBank0(gb, memory->mbcState.mmm01.currentBank0);
 845			break;
 846		case 0x1:
 847			memory->mbcState.mmm01.currentBank0 &= ~0x7F;
 848			memory->mbcState.mmm01.currentBank0 |= value & 0x7F;
 849			break;
 850		case 0x2:
 851			memory->mbcState.mmm01.currentBank0 &= ~0x180;
 852			memory->mbcState.mmm01.currentBank0 |= (value & 0x30) << 3;
 853			break;
 854		default:
 855			// TODO
 856			mLOG(GB_MBC, STUB, "MMM01 unknown address: %04X:%02X", address, value);
 857			break;
 858		}
 859		return;
 860	}
 861	switch (address >> 13) {
 862	case 0x0:
 863		switch (value) {
 864		case 0xA:
 865			memory->sramAccess = true;
 866			GBMBCSwitchSramBank(gb, memory->sramCurrentBank);
 867			break;
 868		default:
 869			memory->sramAccess = false;
 870			break;
 871		}
 872		break;
 873	case 0x1:
 874		GBMBCSwitchBank(gb, value + memory->mbcState.mmm01.currentBank0);
 875		break;
 876	case 0x2:
 877		GBMBCSwitchSramBank(gb, value);
 878		break;
 879	default:
 880		// TODO
 881		mLOG(GB_MBC, STUB, "MMM01 unknown address: %04X:%02X", address, value);
 882		break;
 883	}
 884}
 885
 886void _GBHuC1(struct GB* gb, uint16_t address, uint8_t value) {
 887	struct GBMemory* memory = &gb->memory;
 888	int bank = value & 0x3F;
 889	switch (address >> 13) {
 890	case 0x0:
 891		switch (value) {
 892		case 0xE:
 893			memory->sramAccess = false;
 894			break;
 895		default:
 896			memory->sramAccess = true;
 897			GBMBCSwitchSramBank(gb, memory->sramCurrentBank);
 898			break;
 899		}
 900		break;
 901	case 0x1:
 902		GBMBCSwitchBank(gb, bank);
 903		break;
 904	case 0x2:
 905		GBMBCSwitchSramBank(gb, value);
 906		break;
 907	default:
 908		// TODO
 909		mLOG(GB_MBC, STUB, "HuC-1 unknown address: %04X:%02X", address, value);
 910		break;
 911	}
 912}
 913
 914void _GBHuC3(struct GB* gb, uint16_t address, uint8_t value) {
 915	struct GBMemory* memory = &gb->memory;
 916	int bank = value & 0x3F;
 917	if (address & 0x1FFF) {
 918		mLOG(GB_MBC, STUB, "HuC-3 unknown value %04X:%02X", address, value);
 919	}
 920
 921	switch (address >> 13) {
 922	case 0x0:
 923		switch (value) {
 924		case 0xA:
 925			memory->sramAccess = true;
 926			GBMBCSwitchSramBank(gb, memory->sramCurrentBank);
 927			break;
 928		default:
 929			memory->sramAccess = false;
 930			break;
 931		}
 932		break;
 933	case 0x1:
 934		GBMBCSwitchBank(gb, bank);
 935		break;
 936	case 0x2:
 937		GBMBCSwitchSramBank(gb, bank);
 938		break;
 939	default:
 940		// TODO
 941		mLOG(GB_MBC, STUB, "HuC-3 unknown address: %04X:%02X", address, value);
 942		break;
 943	}
 944}
 945
 946void _GBPocketCam(struct GB* gb, uint16_t address, uint8_t value) {
 947	struct GBMemory* memory = &gb->memory;
 948	int bank = value & 0x3F;
 949	switch (address >> 13) {
 950	case 0x0:
 951		switch (value) {
 952		case 0:
 953			memory->sramAccess = false;
 954			break;
 955		case 0xA:
 956			memory->sramAccess = true;
 957			GBMBCSwitchSramBank(gb, memory->sramCurrentBank);
 958			break;
 959		default:
 960			// TODO
 961			mLOG(GB_MBC, STUB, "Pocket Cam unknown value %02X", value);
 962			break;
 963		}
 964		break;
 965	case 0x1:
 966		GBMBCSwitchBank(gb, bank);
 967		break;
 968	case 0x2:
 969		if (value < 0x10) {
 970			GBMBCSwitchSramBank(gb, value);
 971			memory->mbcState.pocketCam.registersActive = false;
 972		} else {
 973			memory->mbcState.pocketCam.registersActive = true;
 974		}
 975		break;
 976	case 0x5:
 977		address &= 0x7F;
 978		if (address == 0 && value & 1) {
 979			value &= 6; // TODO: Timing
 980			_GBPocketCamCapture(memory);
 981		}
 982		if (address < sizeof(memory->mbcState.pocketCam.registers)) {
 983			memory->mbcState.pocketCam.registers[address] = value;
 984		}
 985		break;
 986	default:
 987		mLOG(GB_MBC, STUB, "Pocket Cam unknown address: %04X:%02X", address, value);
 988		break;
 989	}
 990}
 991
 992uint8_t _GBPocketCamRead(struct GBMemory* memory, uint16_t address) {
 993	if (memory->mbcState.pocketCam.registersActive) {
 994		if ((address & 0x7F) == 0) {
 995			return memory->mbcState.pocketCam.registers[0];
 996		}
 997		return 0;
 998	}
 999	return memory->sramBank[address & (GB_SIZE_EXTERNAL_RAM - 1)];
1000}
1001
1002void _GBPocketCamCapture(struct GBMemory* memory) {
1003	if (!memory->cam) {
1004		return;
1005	}
1006	const void* image = NULL;
1007	size_t stride;
1008	enum mColorFormat format;
1009	memory->cam->requestImage(memory->cam, &image, &stride, &format);
1010	if (!image) {
1011		return;
1012	}
1013	memset(&memory->sram[0x100], 0, GBCAM_HEIGHT * GBCAM_WIDTH / 4);
1014	struct GBPocketCamState* pocketCam = &memory->mbcState.pocketCam;
1015	size_t x, y;
1016	for (y = 0; y < GBCAM_HEIGHT; ++y) {
1017		for (x = 0; x < GBCAM_WIDTH; ++x) {
1018			uint32_t gray;
1019			uint32_t color;
1020			switch (format) {
1021			case mCOLOR_XBGR8:
1022			case mCOLOR_XRGB8:
1023			case mCOLOR_ARGB8:
1024			case mCOLOR_ABGR8:
1025				color = ((const uint32_t*) image)[y * stride + x];
1026				gray = (color & 0xFF) + ((color >> 8) & 0xFF) + ((color >> 16) & 0xFF);
1027				break;
1028			case mCOLOR_BGRX8:
1029			case mCOLOR_RGBX8:
1030			case mCOLOR_RGBA8:
1031			case mCOLOR_BGRA8:
1032				color = ((const uint32_t*) image)[y * stride + x];
1033				gray = ((color >> 8) & 0xFF) + ((color >> 16) & 0xFF) + ((color >> 24) & 0xFF);
1034				break;
1035			case mCOLOR_BGR5:
1036			case mCOLOR_RGB5:
1037			case mCOLOR_ARGB5:
1038			case mCOLOR_ABGR5:
1039				color = ((const uint16_t*) image)[y * stride + x];
1040				gray = ((color << 3) & 0xF8) + ((color >> 2) & 0xF8) + ((color >> 7) & 0xF8);
1041				break;
1042			case mCOLOR_BGR565:
1043			case mCOLOR_RGB565:
1044				color = ((const uint16_t*) image)[y * stride + x];
1045				gray = ((color << 3) & 0xF8) + ((color >> 3) & 0xFC) + ((color >> 8) & 0xF8);
1046				break;
1047			case mCOLOR_BGRA5:
1048			case mCOLOR_RGBA5:
1049				color = ((const uint16_t*) image)[y * stride + x];
1050				gray = ((color << 2) & 0xF8) + ((color >> 3) & 0xF8) + ((color >> 8) & 0xF8);
1051				break;
1052			default:
1053				mLOG(GB_MBC, WARN, "Unsupported pixel format: %X", format);
1054				return;
1055			}
1056			uint16_t exposure = (pocketCam->registers[2] << 8) | (pocketCam->registers[3]);
1057			gray = (gray + 1) * exposure / 0x300;
1058			// TODO: Additional processing
1059			int matrixEntry = 3 * ((x & 3) + 4 * (y & 3));
1060			if (gray < pocketCam->registers[matrixEntry + 6]) {
1061				gray = 0x101;
1062			} else if (gray < pocketCam->registers[matrixEntry + 7]) {
1063				gray = 0x100;
1064			} else if (gray < pocketCam->registers[matrixEntry + 8]) {
1065				gray = 0x001;
1066			} else {
1067				gray = 0;
1068			}
1069			int coord = (((x >> 3) & 0xF) * 8 + (y & 0x7)) * 2 + (y & ~0x7) * 0x20;
1070			uint16_t existing;
1071			LOAD_16LE(existing, coord + 0x100, memory->sram);
1072			existing |= gray << (7 - (x & 7));
1073			STORE_16LE(existing, coord + 0x100, memory->sram);
1074		}
1075	}
1076}
1077
1078void _GBTAMA5(struct GB* gb, uint16_t address, uint8_t value) {
1079	struct GBMemory* memory = &gb->memory;
1080	struct GBTAMA5State* tama5 = &memory->mbcState.tama5;
1081	switch (address >> 13) {
1082	case 0x5:
1083		if (address & 1) {
1084			tama5->reg = value;
1085		} else {
1086			value &= 0xF;
1087			if (tama5->reg < GBTAMA5_MAX) {
1088				tama5->registers[tama5->reg] = value;
1089				uint8_t address = ((tama5->registers[GBTAMA5_CS] << 4) & 0x10) | tama5->registers[GBTAMA5_ADDR_LO];
1090				uint8_t out = (tama5->registers[GBTAMA5_WRITE_HI] << 4) | tama5->registers[GBTAMA5_WRITE_LO];
1091				switch (tama5->reg) {
1092				case GBTAMA5_BANK_LO:
1093				case GBTAMA5_BANK_HI:
1094					GBMBCSwitchBank(gb, tama5->registers[GBTAMA5_BANK_LO] | (tama5->registers[GBTAMA5_BANK_HI] << 4));
1095					break;
1096				case GBTAMA5_WRITE_LO:
1097				case GBTAMA5_WRITE_HI:
1098				case GBTAMA5_CS:
1099					break;
1100				case GBTAMA5_ADDR_LO:
1101					switch (tama5->registers[GBTAMA5_CS] >> 1) {
1102					case 0x0: // RAM write
1103						memory->sram[address] = out;
1104						break;
1105					case 0x1: // RAM read
1106						break;
1107					default:
1108						mLOG(GB_MBC, STUB, "TAMA5 unknown address: %X-%02X:%02X", tama5->registers[GBTAMA5_CS] >> 1, address, out);
1109					}
1110					break;
1111				default:
1112					mLOG(GB_MBC, STUB, "TAMA5 unknown write: %02X:%X", tama5->reg, value);
1113					break;
1114				}
1115			} else {
1116				mLOG(GB_MBC, STUB, "TAMA5 unknown write: %02X", tama5->reg);
1117			}
1118		}
1119		break;
1120	default:
1121		mLOG(GB_MBC, STUB, "TAMA5 unknown address: %04X:%02X", address, value);
1122	}
1123}
1124
1125uint8_t _GBTAMA5Read(struct GBMemory* memory, uint16_t address) {
1126	struct GBTAMA5State* tama5 = &memory->mbcState.tama5;
1127	if ((address & 0x1FFF) > 1) {
1128		mLOG(GB_MBC, STUB, "TAMA5 unknown address: %04X", address);
1129	}
1130	if (address & 1) {
1131		return 0xFF;
1132	} else {
1133		uint8_t value = 0xF0;
1134		uint8_t address = ((tama5->registers[GBTAMA5_CS] << 4) & 0x10) | tama5->registers[GBTAMA5_ADDR_LO];
1135		switch (tama5->reg) {
1136		case GBTAMA5_ACTIVE:
1137			return 0xF1;
1138		case GBTAMA5_READ_LO:
1139		case GBTAMA5_READ_HI:
1140			switch (tama5->registers[GBTAMA5_CS] >> 1) {
1141			case 1:
1142				value = memory->sram[address];
1143				break;
1144			default:
1145				mLOG(GB_MBC, STUB, "TAMA5 unknown read: %02X", tama5->reg);
1146				break;
1147			}
1148			if (tama5->reg == GBTAMA5_READ_HI) {
1149				value >>= 4;
1150			}
1151			value |= 0xF0;
1152			return value;
1153		default:
1154			mLOG(GB_MBC, STUB, "TAMA5 unknown read: %02X", tama5->reg);
1155			return 0xF1;
1156		}
1157	}
1158}
1159
1160void GBMBCRTCRead(struct GB* gb) {
1161	struct GBMBCRTCSaveBuffer rtcBuffer;
1162	struct VFile* vf = gb->sramVf;
1163	if (!vf) {
1164		return;
1165	}
1166	vf->seek(vf, gb->sramSize, SEEK_SET);
1167	if (vf->read(vf, &rtcBuffer, sizeof(rtcBuffer)) < (ssize_t) sizeof(rtcBuffer) - 4) {
1168		return;
1169	}
1170
1171	LOAD_32LE(gb->memory.rtcRegs[0], 0, &rtcBuffer.latchedSec);
1172	LOAD_32LE(gb->memory.rtcRegs[1], 0, &rtcBuffer.latchedMin);
1173	LOAD_32LE(gb->memory.rtcRegs[2], 0, &rtcBuffer.latchedHour);
1174	LOAD_32LE(gb->memory.rtcRegs[3], 0, &rtcBuffer.latchedDays);
1175	LOAD_32LE(gb->memory.rtcRegs[4], 0, &rtcBuffer.latchedDaysHi);
1176	LOAD_64LE(gb->memory.rtcLastLatch, 0, &rtcBuffer.unixTime);
1177}
1178
1179void GBMBCRTCWrite(struct GB* gb) {
1180	struct VFile* vf = gb->sramVf;
1181	if (!vf) {
1182		return;
1183	}
1184
1185	uint8_t rtcRegs[5];
1186	memcpy(rtcRegs, gb->memory.rtcRegs, sizeof(rtcRegs));
1187	time_t rtcLastLatch = gb->memory.rtcLastLatch;
1188	_latchRtc(gb->memory.rtc, rtcRegs, &rtcLastLatch);
1189
1190	struct GBMBCRTCSaveBuffer rtcBuffer;
1191	STORE_32LE(rtcRegs[0], 0, &rtcBuffer.sec);
1192	STORE_32LE(rtcRegs[1], 0, &rtcBuffer.min);
1193	STORE_32LE(rtcRegs[2], 0, &rtcBuffer.hour);
1194	STORE_32LE(rtcRegs[3], 0, &rtcBuffer.days);
1195	STORE_32LE(rtcRegs[4], 0, &rtcBuffer.daysHi);
1196	STORE_32LE(gb->memory.rtcRegs[0], 0, &rtcBuffer.latchedSec);
1197	STORE_32LE(gb->memory.rtcRegs[1], 0, &rtcBuffer.latchedMin);
1198	STORE_32LE(gb->memory.rtcRegs[2], 0, &rtcBuffer.latchedHour);
1199	STORE_32LE(gb->memory.rtcRegs[3], 0, &rtcBuffer.latchedDays);
1200	STORE_32LE(gb->memory.rtcRegs[4], 0, &rtcBuffer.latchedDaysHi);
1201	STORE_64LE(gb->memory.rtcLastLatch, 0, &rtcBuffer.unixTime);
1202
1203	if ((size_t) vf->size(vf) < gb->sramSize + sizeof(rtcBuffer)) {
1204		// Writing past the end of the file can invalidate the file mapping
1205		vf->unmap(vf, gb->memory.sram, gb->sramSize);
1206		gb->memory.sram = NULL;
1207	}
1208	vf->seek(vf, gb->sramSize, SEEK_SET);
1209	vf->write(vf, &rtcBuffer, sizeof(rtcBuffer));
1210	if (!gb->memory.sram) {
1211		gb->memory.sram = vf->map(vf, gb->sramSize, MAP_WRITE);
1212		GBMBCSwitchSramBank(gb, gb->memory.sramCurrentBank);
1213	}
1214}