all repos — mgba @ 8361d56683bf5078701e1a4392d08b9b765392bd

mGBA Game Boy Advance Emulator

src/gb/io.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/io.h>
  7
  8#include <mgba/internal/gb/gb.h>
  9#include <mgba/internal/gb/sio.h>
 10#include <mgba/internal/gb/serialize.h>
 11
 12mLOG_DEFINE_CATEGORY(GB_IO, "GB I/O", "gb.io");
 13
 14MGBA_EXPORT const char* const GBIORegisterNames[] = {
 15	[GB_REG_JOYP] = "JOYP",
 16	[GB_REG_SB] = "SB",
 17	[GB_REG_SC] = "SC",
 18	[GB_REG_DIV] = "DIV",
 19	[GB_REG_TIMA] = "TIMA",
 20	[GB_REG_TMA] = "TMA",
 21	[GB_REG_TAC] = "TAC",
 22	[GB_REG_IF] = "IF",
 23	[GB_REG_NR10] = "NR10",
 24	[GB_REG_NR11] = "NR11",
 25	[GB_REG_NR12] = "NR12",
 26	[GB_REG_NR13] = "NR13",
 27	[GB_REG_NR14] = "NR14",
 28	[GB_REG_NR21] = "NR21",
 29	[GB_REG_NR22] = "NR22",
 30	[GB_REG_NR23] = "NR23",
 31	[GB_REG_NR24] = "NR24",
 32	[GB_REG_NR30] = "NR30",
 33	[GB_REG_NR31] = "NR31",
 34	[GB_REG_NR32] = "NR32",
 35	[GB_REG_NR33] = "NR33",
 36	[GB_REG_NR34] = "NR34",
 37	[GB_REG_NR41] = "NR41",
 38	[GB_REG_NR42] = "NR42",
 39	[GB_REG_NR43] = "NR43",
 40	[GB_REG_NR44] = "NR44",
 41	[GB_REG_NR50] = "NR50",
 42	[GB_REG_NR51] = "NR51",
 43	[GB_REG_NR52] = "NR52",
 44	[GB_REG_LCDC] = "LCDC",
 45	[GB_REG_STAT] = "STAT",
 46	[GB_REG_SCY] = "SCY",
 47	[GB_REG_SCX] = "SCX",
 48	[GB_REG_LY] = "LY",
 49	[GB_REG_LYC] = "LYC",
 50	[GB_REG_DMA] = "DMA",
 51	[GB_REG_BGP] = "BGP",
 52	[GB_REG_OBP0] = "OBP0",
 53	[GB_REG_OBP1] = "OBP1",
 54	[GB_REG_WY] = "WY",
 55	[GB_REG_WX] = "WX",
 56	[GB_REG_KEY0] = "KEY0",
 57	[GB_REG_KEY1] = "KEY1",
 58	[GB_REG_VBK] = "VBK",
 59	[GB_REG_BANK] = "BANK",
 60	[GB_REG_HDMA1] = "HDMA1",
 61	[GB_REG_HDMA2] = "HDMA2",
 62	[GB_REG_HDMA3] = "HDMA3",
 63	[GB_REG_HDMA4] = "HDMA4",
 64	[GB_REG_HDMA5] = "HDMA5",
 65	[GB_REG_RP] = "RP",
 66	[GB_REG_BCPS] = "BCPS",
 67	[GB_REG_BCPD] = "BCPD",
 68	[GB_REG_OCPS] = "OCPS",
 69	[GB_REG_OCPD] = "OCPD",
 70	[GB_REG_OPRI] = "OPRI",
 71	[GB_REG_SVBK] = "SVBK",
 72	[GB_REG_IE] = "IE",
 73};
 74
 75static const uint8_t _registerMask[] = {
 76	[GB_REG_SC]   = 0x7E, // TODO: GBC differences
 77	[GB_REG_IF]   = 0xE0,
 78	[GB_REG_TAC]  = 0xF8,
 79	[GB_REG_NR10] = 0x80,
 80	[GB_REG_NR11] = 0x3F,
 81	[GB_REG_NR12] = 0x00,
 82	[GB_REG_NR13] = 0xFF,
 83	[GB_REG_NR14] = 0xBF,
 84	[GB_REG_NR21] = 0x3F,
 85	[GB_REG_NR22] = 0x00,
 86	[GB_REG_NR23] = 0xFF,
 87	[GB_REG_NR24] = 0xBF,
 88	[GB_REG_NR30] = 0x7F,
 89	[GB_REG_NR31] = 0xFF,
 90	[GB_REG_NR32] = 0x9F,
 91	[GB_REG_NR33] = 0xFF,
 92	[GB_REG_NR34] = 0xBF,
 93	[GB_REG_NR41] = 0xFF,
 94	[GB_REG_NR42] = 0x00,
 95	[GB_REG_NR43] = 0x00,
 96	[GB_REG_NR44] = 0xBF,
 97	[GB_REG_NR50] = 0x00,
 98	[GB_REG_NR51] = 0x00,
 99	[GB_REG_NR52] = 0x70,
100	[GB_REG_STAT] = 0x80,
101	[GB_REG_KEY1] = 0x7E,
102	[GB_REG_VBK]  = 0xFE,
103	[GB_REG_OCPS] = 0x40,
104	[GB_REG_BCPS] = 0x40,
105	[GB_REG_OPRI] = 0xFE,
106	[GB_REG_SVBK] = 0xF8,
107	[GB_REG_UNK75] = 0x8F,
108	[GB_REG_IE]   = 0xE0,
109};
110
111static uint8_t _readKeys(struct GB* gb);
112static uint8_t _readKeysFiltered(struct GB* gb);
113
114static void _writeSGBBits(struct GB* gb, int bits) {
115	if (!bits) {
116		gb->sgbBit = -1;
117		memset(gb->sgbPacket, 0, sizeof(gb->sgbPacket));
118	}
119	if (bits == gb->currentSgbBits) {
120		return;
121	}
122	switch (bits) {
123	case 0:
124	case 1:
125		if (gb->currentSgbBits & 2) {
126			gb->sgbIncrement = !gb->sgbIncrement;
127		}
128		break;
129	case 3:
130		if (gb->sgbIncrement) {
131			gb->sgbIncrement = false;
132			gb->sgbCurrentController = (gb->sgbCurrentController + 1) & gb->sgbControllers;
133		}
134		break;
135	}
136	gb->currentSgbBits = bits;
137	if (gb->sgbBit == 128 && bits == 2) {
138		GBVideoWriteSGBPacket(&gb->video, gb->sgbPacket);
139		++gb->sgbBit;
140	}
141	if (gb->sgbBit >= 128) {
142		return;
143	}
144	switch (bits) {
145	case 1:
146		if (gb->sgbBit < 0) {
147			return;
148		}
149		gb->sgbPacket[gb->sgbBit >> 3] |= 1 << (gb->sgbBit & 7);
150		break;
151	case 3:
152		++gb->sgbBit;
153	default:
154		break;
155	}
156}
157
158void GBIOInit(struct GB* gb) {
159	memset(gb->memory.io, 0, sizeof(gb->memory.io));
160}
161
162void GBIOReset(struct GB* gb) {
163	memset(gb->memory.io, 0, sizeof(gb->memory.io));
164
165	GBIOWrite(gb, GB_REG_TIMA, 0);
166	GBIOWrite(gb, GB_REG_TMA, 0);
167	GBIOWrite(gb, GB_REG_TAC, 0);
168	GBIOWrite(gb, GB_REG_IF, 1);
169	GBIOWrite(gb, GB_REG_NR52, 0xF1);
170	GBIOWrite(gb, GB_REG_NR14, 0x3F);
171	GBIOWrite(gb, GB_REG_NR10, 0x80);
172	GBIOWrite(gb, GB_REG_NR11, 0xBF);
173	GBIOWrite(gb, GB_REG_NR12, 0xF3);
174	GBIOWrite(gb, GB_REG_NR13, 0xF3);
175	GBIOWrite(gb, GB_REG_NR24, 0x3F);
176	GBIOWrite(gb, GB_REG_NR21, 0x3F);
177	GBIOWrite(gb, GB_REG_NR22, 0x00);
178	GBIOWrite(gb, GB_REG_NR34, 0x3F);
179	GBIOWrite(gb, GB_REG_NR30, 0x7F);
180	GBIOWrite(gb, GB_REG_NR31, 0xFF);
181	GBIOWrite(gb, GB_REG_NR32, 0x9F);
182	GBIOWrite(gb, GB_REG_NR44, 0x3F);
183	GBIOWrite(gb, GB_REG_NR41, 0xFF);
184	GBIOWrite(gb, GB_REG_NR42, 0x00);
185	GBIOWrite(gb, GB_REG_NR43, 0x00);
186	GBIOWrite(gb, GB_REG_NR50, 0x77);
187	GBIOWrite(gb, GB_REG_NR51, 0xF3);
188	if (!gb->biosVf) {
189		GBIOWrite(gb, GB_REG_LCDC, 0x91);
190		gb->memory.io[GB_REG_BANK] = 1;
191	} else {
192		GBIOWrite(gb, GB_REG_LCDC, 0x00);
193		gb->memory.io[GB_REG_BANK] = 0xFF;
194	}
195	GBIOWrite(gb, GB_REG_SCY, 0x00);
196	GBIOWrite(gb, GB_REG_SCX, 0x00);
197	GBIOWrite(gb, GB_REG_LYC, 0x00);
198	gb->memory.io[GB_REG_DMA] = 0xFF;
199	GBIOWrite(gb, GB_REG_BGP, 0xFC);
200	if (gb->model < GB_MODEL_CGB) {
201		GBIOWrite(gb, GB_REG_OBP0, 0xFF);
202		GBIOWrite(gb, GB_REG_OBP1, 0xFF);
203	}
204	GBIOWrite(gb, GB_REG_WY, 0x00);
205	GBIOWrite(gb, GB_REG_WX, 0x00);
206	if (gb->model & GB_MODEL_CGB) {
207		GBIOWrite(gb, GB_REG_KEY0, 0);
208		GBIOWrite(gb, GB_REG_JOYP, 0xFF);
209		GBIOWrite(gb, GB_REG_VBK, 0);
210		GBIOWrite(gb, GB_REG_BCPS, 0x80);
211		GBIOWrite(gb, GB_REG_OCPS, 0);
212		GBIOWrite(gb, GB_REG_SVBK, 1);
213		GBIOWrite(gb, GB_REG_HDMA1, 0xFF);
214		GBIOWrite(gb, GB_REG_HDMA2, 0xFF);
215		GBIOWrite(gb, GB_REG_HDMA3, 0xFF);
216		GBIOWrite(gb, GB_REG_HDMA4, 0xFF);
217		gb->memory.io[GB_REG_HDMA5] = 0xFF;
218	} else {
219		memset(&gb->memory.io[GB_REG_KEY0], 0xFF, GB_REG_PCM34 - GB_REG_KEY0 + 1);
220	}
221
222	if (gb->model & GB_MODEL_SGB) {
223		GBIOWrite(gb, GB_REG_JOYP, 0xFF);
224	}
225	GBIOWrite(gb, GB_REG_IE, 0x00);
226}
227
228void GBIOWrite(struct GB* gb, unsigned address, uint8_t value) {
229	switch (address) {
230	case GB_REG_SB:
231		GBSIOWriteSB(&gb->sio, value);
232		break;
233	case GB_REG_SC:
234		GBSIOWriteSC(&gb->sio, value);
235		break;
236	case GB_REG_DIV:
237		GBTimerDivReset(&gb->timer);
238		return;
239	case GB_REG_NR10:
240		if (gb->audio.enable) {
241			GBAudioWriteNR10(&gb->audio, value);
242		} else {
243			value = 0;
244		}
245		break;
246	case GB_REG_NR11:
247		if (gb->audio.enable) {
248			GBAudioWriteNR11(&gb->audio, value);
249		} else {
250			if (gb->audio.style == GB_AUDIO_DMG) {
251				GBAudioWriteNR11(&gb->audio, value & _registerMask[GB_REG_NR11]);
252			}
253			value = 0;
254		}
255		break;
256	case GB_REG_NR12:
257		if (gb->audio.enable) {
258			GBAudioWriteNR12(&gb->audio, value);
259		} else {
260			value = 0;
261		}
262		break;
263	case GB_REG_NR13:
264		if (gb->audio.enable) {
265			GBAudioWriteNR13(&gb->audio, value);
266		} else {
267			value = 0;
268		}
269		break;
270	case GB_REG_NR14:
271		if (gb->audio.enable) {
272			GBAudioWriteNR14(&gb->audio, value);
273		} else {
274			value = 0;
275		}
276		break;
277	case GB_REG_NR21:
278		if (gb->audio.enable) {
279			GBAudioWriteNR21(&gb->audio, value);
280		} else {
281			if (gb->audio.style == GB_AUDIO_DMG) {
282				GBAudioWriteNR21(&gb->audio, value & _registerMask[GB_REG_NR21]);
283			}
284			value = 0;
285		}
286		break;
287	case GB_REG_NR22:
288		if (gb->audio.enable) {
289			GBAudioWriteNR22(&gb->audio, value);
290		} else {
291			value = 0;
292		}
293		break;
294	case GB_REG_NR23:
295		if (gb->audio.enable) {
296			GBAudioWriteNR23(&gb->audio, value);
297		} else {
298			value = 0;
299		}
300		break;
301	case GB_REG_NR24:
302		if (gb->audio.enable) {
303			GBAudioWriteNR24(&gb->audio, value);
304		} else {
305			value = 0;
306		}
307		break;
308	case GB_REG_NR30:
309		if (gb->audio.enable) {
310			GBAudioWriteNR30(&gb->audio, value);
311		} else {
312			value = 0;
313		}
314		break;
315	case GB_REG_NR31:
316		if (gb->audio.enable || gb->audio.style == GB_AUDIO_DMG) {
317			GBAudioWriteNR31(&gb->audio, value);
318		} else {
319			value = 0;
320		}
321		break;
322	case GB_REG_NR32:
323		if (gb->audio.enable) {
324			GBAudioWriteNR32(&gb->audio, value);
325		} else {
326			value = 0;
327		}
328		break;
329	case GB_REG_NR33:
330		if (gb->audio.enable) {
331			GBAudioWriteNR33(&gb->audio, value);
332		} else {
333			value = 0;
334		}
335		break;
336	case GB_REG_NR34:
337		if (gb->audio.enable) {
338			GBAudioWriteNR34(&gb->audio, value);
339		} else {
340			value = 0;
341		}
342		break;
343	case GB_REG_NR41:
344		if (gb->audio.enable || gb->audio.style == GB_AUDIO_DMG) {
345			GBAudioWriteNR41(&gb->audio, value);
346		} else {
347			value = 0;
348		}
349		break;
350	case GB_REG_NR42:
351		if (gb->audio.enable) {
352			GBAudioWriteNR42(&gb->audio, value);
353		} else {
354			value = 0;
355		}
356		break;
357	case GB_REG_NR43:
358		if (gb->audio.enable) {
359			GBAudioWriteNR43(&gb->audio, value);
360		} else {
361			value = 0;
362		}
363		break;
364	case GB_REG_NR44:
365		if (gb->audio.enable) {
366			GBAudioWriteNR44(&gb->audio, value);
367		} else {
368			value = 0;
369		}
370		break;
371	case GB_REG_NR50:
372		if (gb->audio.enable) {
373			GBAudioWriteNR50(&gb->audio, value);
374		} else {
375			value = 0;
376		}
377		break;
378	case GB_REG_NR51:
379		if (gb->audio.enable) {
380			GBAudioWriteNR51(&gb->audio, value);
381		} else {
382			value = 0;
383		}
384		break;
385	case GB_REG_NR52:
386		GBAudioWriteNR52(&gb->audio, value);
387		value &= 0x80;
388		value |= gb->memory.io[GB_REG_NR52] & 0x0F;
389		break;
390	case GB_REG_WAVE_0:
391	case GB_REG_WAVE_1:
392	case GB_REG_WAVE_2:
393	case GB_REG_WAVE_3:
394	case GB_REG_WAVE_4:
395	case GB_REG_WAVE_5:
396	case GB_REG_WAVE_6:
397	case GB_REG_WAVE_7:
398	case GB_REG_WAVE_8:
399	case GB_REG_WAVE_9:
400	case GB_REG_WAVE_A:
401	case GB_REG_WAVE_B:
402	case GB_REG_WAVE_C:
403	case GB_REG_WAVE_D:
404	case GB_REG_WAVE_E:
405	case GB_REG_WAVE_F:
406		if (!gb->audio.playingCh3 || gb->audio.style != GB_AUDIO_DMG) {
407			gb->audio.ch3.wavedata8[address - GB_REG_WAVE_0] = value;
408		} else if(gb->audio.ch3.readable) {
409			gb->audio.ch3.wavedata8[gb->audio.ch3.window >> 1] = value;
410		}
411		break;
412	case GB_REG_JOYP:
413		gb->memory.io[GB_REG_JOYP] = value | 0x0F;
414		_readKeys(gb);
415		if (gb->model & GB_MODEL_SGB) {
416			_writeSGBBits(gb, (value >> 4) & 3);
417		}
418		return;
419	case GB_REG_TIMA:
420		if (value && mTimingUntil(&gb->timing, &gb->timer.irq) > 1) {
421			mTimingDeschedule(&gb->timing, &gb->timer.irq);
422		}
423		if (mTimingUntil(&gb->timing, &gb->timer.irq) == -1) {
424			return;
425		}
426		break;
427	case GB_REG_TMA:
428		if (mTimingUntil(&gb->timing, &gb->timer.irq) == -1) {
429			gb->memory.io[GB_REG_TIMA] = value;
430		}
431		break;
432	case GB_REG_TAC:
433		value = GBTimerUpdateTAC(&gb->timer, value);
434		break;
435	case GB_REG_IF:
436		gb->memory.io[GB_REG_IF] = value | 0xE0;
437		GBUpdateIRQs(gb);
438		return;
439	case GB_REG_LCDC:
440		// TODO: handle GBC differences
441		GBVideoProcessDots(&gb->video, 0);
442		value = gb->video.renderer->writeVideoRegister(gb->video.renderer, address, value);
443		GBVideoWriteLCDC(&gb->video, value);
444		break;
445	case GB_REG_LYC:
446		GBVideoWriteLYC(&gb->video, value);
447		break;
448	case GB_REG_DMA:
449		GBMemoryDMA(gb, value << 8);
450		break;
451	case GB_REG_SCY:
452	case GB_REG_SCX:
453	case GB_REG_WY:
454	case GB_REG_WX:
455		GBVideoProcessDots(&gb->video, 0);
456		value = gb->video.renderer->writeVideoRegister(gb->video.renderer, address, value);
457		break;
458	case GB_REG_BGP:
459	case GB_REG_OBP0:
460	case GB_REG_OBP1:
461		GBVideoProcessDots(&gb->video, 0);
462		GBVideoWritePalette(&gb->video, address, value);
463		break;
464	case GB_REG_STAT:
465		GBVideoWriteSTAT(&gb->video, value);
466		value = gb->video.stat;
467		break;
468	case GB_REG_BANK:
469		if (gb->memory.io[GB_REG_BANK] != 0xFF) {
470			break;
471		}
472		GBUnmapBIOS(gb);
473		if (gb->model >= GB_MODEL_CGB && gb->memory.io[GB_REG_KEY0] < 0x80) {
474			gb->model = GB_MODEL_DMG;
475			GBVideoDisableCGB(&gb->video);
476		}
477		break;
478	case GB_REG_IE:
479		gb->memory.ie = value;
480		GBUpdateIRQs(gb);
481		return;
482	default:
483		if (gb->model >= GB_MODEL_CGB) {
484			switch (address) {
485			case GB_REG_KEY0:
486				break;
487			case GB_REG_KEY1:
488				value &= 0x1;
489				value |= gb->memory.io[address] & 0x80;
490				break;
491			case GB_REG_VBK:
492				GBVideoSwitchBank(&gb->video, value);
493				break;
494			case GB_REG_HDMA1:
495			case GB_REG_HDMA2:
496			case GB_REG_HDMA3:
497			case GB_REG_HDMA4:
498				// Handled transparently by the registers
499				break;
500			case GB_REG_HDMA5:
501				value = GBMemoryWriteHDMA5(gb, value);
502				break;
503			case GB_REG_BCPS:
504				gb->video.bcpIndex = value & 0x3F;
505				gb->video.bcpIncrement = value & 0x80;
506				gb->memory.io[GB_REG_BCPD] = gb->video.palette[gb->video.bcpIndex >> 1] >> (8 * (gb->video.bcpIndex & 1));
507				break;
508			case GB_REG_BCPD:
509				if (gb->video.mode != 3) {
510					GBVideoProcessDots(&gb->video, 0);
511				}
512				GBVideoWritePalette(&gb->video, address, value);
513				return;
514			case GB_REG_OCPS:
515				gb->video.ocpIndex = value & 0x3F;
516				gb->video.ocpIncrement = value & 0x80;
517				gb->memory.io[GB_REG_OCPD] = gb->video.palette[8 * 4 + (gb->video.ocpIndex >> 1)] >> (8 * (gb->video.ocpIndex & 1));
518				break;
519			case GB_REG_OCPD:
520				if (gb->video.mode != 3) {
521					GBVideoProcessDots(&gb->video, 0);
522				}
523				GBVideoWritePalette(&gb->video, address, value);
524				return;
525			case GB_REG_SVBK:
526				GBMemorySwitchWramBank(&gb->memory, value);
527				value = gb->memory.wramCurrentBank;
528				break;
529			default:
530				goto failed;
531			}
532			goto success;
533		}
534		failed:
535		mLOG(GB_IO, GAME_ERROR, "Writing to unknown register FF%02X:%02X", address, value);
536		return;
537	}
538	success:
539	gb->memory.io[address] = value;
540}
541
542static uint8_t _readKeys(struct GB* gb) {
543	uint8_t keys = *gb->keySource;
544	if (gb->sgbCurrentController != 0) {
545		keys = 0;
546	}
547	uint8_t joyp = gb->memory.io[GB_REG_JOYP];
548	switch (joyp & 0x30) {
549	case 0x30:
550		keys = gb->sgbCurrentController;
551		break;
552	case 0x20:
553		keys >>= 4;
554		break;
555	case 0x10:
556		break;
557	case 0x00:
558		keys |= keys >> 4;
559		break;
560	}
561	gb->memory.io[GB_REG_JOYP] = (0xCF | joyp) ^ (keys & 0xF);
562	if (joyp & ~gb->memory.io[GB_REG_JOYP] & 0xF) {
563		gb->memory.io[GB_REG_IF] |= (1 << GB_IRQ_KEYPAD);
564		GBUpdateIRQs(gb);
565	}
566	return gb->memory.io[GB_REG_JOYP];
567}
568
569static uint8_t _readKeysFiltered(struct GB* gb) {
570	uint8_t keys = _readKeys(gb);
571	if (!gb->allowOpposingDirections && (keys & 0x30) == 0x20) {
572		unsigned rl = keys & 0x03;
573		unsigned ud = keys & 0x0C;
574		if (!rl) {
575			keys |= 0x03;
576		}
577		if (!ud) {
578			keys |= 0x0C;
579		}
580	}
581	return keys;
582}
583
584uint8_t GBIORead(struct GB* gb, unsigned address) {
585	switch (address) {
586	case GB_REG_JOYP:
587		{
588			size_t c;
589			for (c = 0; c < mCoreCallbacksListSize(&gb->coreCallbacks); ++c) {
590				struct mCoreCallbacks* callbacks = mCoreCallbacksListGetPointer(&gb->coreCallbacks, c);
591				if (callbacks->keysRead) {
592					callbacks->keysRead(callbacks->context);
593				}
594			}
595		}
596		return _readKeysFiltered(gb);
597	case GB_REG_IE:
598		return gb->memory.ie;
599	case GB_REG_WAVE_0:
600	case GB_REG_WAVE_1:
601	case GB_REG_WAVE_2:
602	case GB_REG_WAVE_3:
603	case GB_REG_WAVE_4:
604	case GB_REG_WAVE_5:
605	case GB_REG_WAVE_6:
606	case GB_REG_WAVE_7:
607	case GB_REG_WAVE_8:
608	case GB_REG_WAVE_9:
609	case GB_REG_WAVE_A:
610	case GB_REG_WAVE_B:
611	case GB_REG_WAVE_C:
612	case GB_REG_WAVE_D:
613	case GB_REG_WAVE_E:
614	case GB_REG_WAVE_F:
615		if (gb->audio.playingCh3) {
616			if (gb->audio.ch3.readable || gb->audio.style != GB_AUDIO_DMG) {
617				return gb->audio.ch3.wavedata8[gb->audio.ch3.window >> 1];
618			} else {
619				return 0xFF;
620			}
621		} else {
622			return gb->audio.ch3.wavedata8[address - GB_REG_WAVE_0];
623		}
624		break;
625	case GB_REG_PCM12:
626		if (gb->model < GB_MODEL_CGB) {
627			mLOG(GB_IO, GAME_ERROR, "Reading from CGB register FF%02X in DMG mode", address);
628		} else if (gb->audio.enable) {
629			return (gb->audio.ch1.sample) | (gb->audio.ch2.sample << 4);
630		}
631		break;
632	case GB_REG_PCM34:
633		if (gb->model < GB_MODEL_CGB) {
634			mLOG(GB_IO, GAME_ERROR, "Reading from CGB register FF%02X in DMG mode", address);
635		} else if (gb->audio.enable) {
636			return (gb->audio.ch3.sample) | (gb->audio.ch4.sample << 4);
637		}
638		break;
639	case GB_REG_SB:
640	case GB_REG_SC:
641	case GB_REG_IF:
642	case GB_REG_NR10:
643	case GB_REG_NR11:
644	case GB_REG_NR12:
645	case GB_REG_NR14:
646	case GB_REG_NR21:
647	case GB_REG_NR22:
648	case GB_REG_NR24:
649	case GB_REG_NR30:
650	case GB_REG_NR32:
651	case GB_REG_NR34:
652	case GB_REG_NR41:
653	case GB_REG_NR42:
654	case GB_REG_NR43:
655	case GB_REG_NR44:
656	case GB_REG_NR50:
657	case GB_REG_NR51:
658	case GB_REG_NR52:
659	case GB_REG_DIV:
660	case GB_REG_TIMA:
661	case GB_REG_TMA:
662	case GB_REG_TAC:
663	case GB_REG_STAT:
664	case GB_REG_LCDC:
665	case GB_REG_SCY:
666	case GB_REG_SCX:
667	case GB_REG_LY:
668	case GB_REG_LYC:
669	case GB_REG_DMA:
670	case GB_REG_BGP:
671	case GB_REG_OBP0:
672	case GB_REG_OBP1:
673	case GB_REG_WY:
674	case GB_REG_WX:
675		// Handled transparently by the registers
676		break;
677	case GB_REG_KEY1:
678	case GB_REG_VBK:
679	case GB_REG_HDMA1:
680	case GB_REG_HDMA2:
681	case GB_REG_HDMA3:
682	case GB_REG_HDMA4:
683	case GB_REG_HDMA5:
684	case GB_REG_BCPS:
685	case GB_REG_BCPD:
686	case GB_REG_OCPS:
687	case GB_REG_OCPD:
688	case GB_REG_SVBK:
689	case GB_REG_UNK72:
690	case GB_REG_UNK73:
691	case GB_REG_UNK75:
692		// Handled transparently by the registers
693		if (gb->model < GB_MODEL_CGB) {
694			// In DMG mode, these all get initialized to 0xFF during reset
695			// But in DMG-on-CGB mode, they get initialized by the CGB reset so they can be non-zero
696			mLOG(GB_IO, GAME_ERROR, "Reading from CGB register FF%02X in DMG mode", address);
697		}
698		break;
699	default:
700		mLOG(GB_IO, STUB, "Reading from unknown register FF%02X", address);
701		return 0xFF;
702	}
703	return gb->memory.io[address] | _registerMask[address];
704}
705
706void GBTestKeypadIRQ(struct GB* gb) {
707	_readKeys(gb);
708}
709
710struct GBSerializedState;
711void GBIOSerialize(const struct GB* gb, struct GBSerializedState* state) {
712	memcpy(state->io, gb->memory.io, GB_SIZE_IO);
713	state->ie = gb->memory.ie;
714}
715
716void GBIODeserialize(struct GB* gb, const struct GBSerializedState* state) {
717	memcpy(gb->memory.io, state->io, GB_SIZE_IO);
718	gb->memory.ie = state->ie;
719
720	gb->audio.enable = GBAudioEnableGetEnable(*gb->audio.nr52);
721	if (gb->audio.enable) {
722		GBIOWrite(gb, GB_REG_NR10, gb->memory.io[GB_REG_NR10]);
723		GBIOWrite(gb, GB_REG_NR11, gb->memory.io[GB_REG_NR11]);
724		GBIOWrite(gb, GB_REG_NR12, gb->memory.io[GB_REG_NR12]);
725		GBIOWrite(gb, GB_REG_NR13, gb->memory.io[GB_REG_NR13]);
726		gb->audio.ch1.control.frequency &= 0xFF;
727		gb->audio.ch1.control.frequency |= GBAudioRegisterControlGetFrequency(gb->memory.io[GB_REG_NR14] << 8);
728		gb->audio.ch1.control.stop = GBAudioRegisterControlGetStop(gb->memory.io[GB_REG_NR14] << 8);
729		GBIOWrite(gb, GB_REG_NR21, gb->memory.io[GB_REG_NR21]);
730		GBIOWrite(gb, GB_REG_NR22, gb->memory.io[GB_REG_NR22]);
731		GBIOWrite(gb, GB_REG_NR23, gb->memory.io[GB_REG_NR23]);
732		gb->audio.ch2.control.frequency &= 0xFF;
733		gb->audio.ch2.control.frequency |= GBAudioRegisterControlGetFrequency(gb->memory.io[GB_REG_NR24] << 8);
734		gb->audio.ch2.control.stop = GBAudioRegisterControlGetStop(gb->memory.io[GB_REG_NR24] << 8);
735		GBIOWrite(gb, GB_REG_NR30, gb->memory.io[GB_REG_NR30]);
736		GBIOWrite(gb, GB_REG_NR31, gb->memory.io[GB_REG_NR31]);
737		GBIOWrite(gb, GB_REG_NR32, gb->memory.io[GB_REG_NR32]);
738		GBIOWrite(gb, GB_REG_NR33, gb->memory.io[GB_REG_NR33]);
739		gb->audio.ch3.rate &= 0xFF;
740		gb->audio.ch3.rate |= GBAudioRegisterControlGetRate(gb->memory.io[GB_REG_NR34] << 8);
741		gb->audio.ch3.stop = GBAudioRegisterControlGetStop(gb->memory.io[GB_REG_NR34] << 8);
742		GBIOWrite(gb, GB_REG_NR41, gb->memory.io[GB_REG_NR41]);
743		GBIOWrite(gb, GB_REG_NR42, gb->memory.io[GB_REG_NR42]);
744		GBIOWrite(gb, GB_REG_NR43, gb->memory.io[GB_REG_NR43]);
745		gb->audio.ch4.stop = GBAudioRegisterNoiseControlGetStop(gb->memory.io[GB_REG_NR44]);
746		GBIOWrite(gb, GB_REG_NR50, gb->memory.io[GB_REG_NR50]);
747		GBIOWrite(gb, GB_REG_NR51, gb->memory.io[GB_REG_NR51]);
748	}
749
750	gb->video.renderer->writeVideoRegister(gb->video.renderer, GB_REG_LCDC, state->io[GB_REG_LCDC]);
751	gb->video.renderer->writeVideoRegister(gb->video.renderer, GB_REG_SCY, state->io[GB_REG_SCY]);
752	gb->video.renderer->writeVideoRegister(gb->video.renderer, GB_REG_SCX, state->io[GB_REG_SCX]);
753	gb->video.renderer->writeVideoRegister(gb->video.renderer, GB_REG_WY, state->io[GB_REG_WY]);
754	gb->video.renderer->writeVideoRegister(gb->video.renderer, GB_REG_WX, state->io[GB_REG_WX]);
755	if (gb->model & GB_MODEL_SGB) {
756		gb->video.renderer->writeVideoRegister(gb->video.renderer, GB_REG_BGP, state->io[GB_REG_BGP]);
757		gb->video.renderer->writeVideoRegister(gb->video.renderer, GB_REG_OBP0, state->io[GB_REG_OBP0]);
758		gb->video.renderer->writeVideoRegister(gb->video.renderer, GB_REG_OBP1, state->io[GB_REG_OBP1]);
759	}
760	gb->video.stat = state->io[GB_REG_STAT];
761}