all repos — mgba @ 4101fe54c670616fc4e5bc7416b3c98fa7aad102

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
 14const char* const GBIORegisterNames[] = {
 15	[REG_JOYP] = "JOYP",
 16	[REG_SB] = "SB",
 17	[REG_SC] = "SC",
 18	[REG_DIV] = "DIV",
 19	[REG_TIMA] = "TIMA",
 20	[REG_TMA] = "TMA",
 21	[REG_TAC] = "TAC",
 22	[REG_IF] = "IF",
 23	[REG_NR10] = "NR10",
 24	[REG_NR11] = "NR11",
 25	[REG_NR12] = "NR12",
 26	[REG_NR13] = "NR13",
 27	[REG_NR14] = "NR14",
 28	[REG_NR21] = "NR21",
 29	[REG_NR22] = "NR22",
 30	[REG_NR23] = "NR23",
 31	[REG_NR24] = "NR24",
 32	[REG_NR30] = "NR30",
 33	[REG_NR31] = "NR31",
 34	[REG_NR32] = "NR32",
 35	[REG_NR33] = "NR33",
 36	[REG_NR34] = "NR34",
 37	[REG_NR41] = "NR41",
 38	[REG_NR42] = "NR42",
 39	[REG_NR43] = "NR43",
 40	[REG_NR44] = "NR44",
 41	[REG_NR50] = "NR50",
 42	[REG_NR51] = "NR51",
 43	[REG_NR52] = "NR52",
 44	[REG_LCDC] = "LCDC",
 45	[REG_STAT] = "STAT",
 46	[REG_SCY] = "SCY",
 47	[REG_SCX] = "SCX",
 48	[REG_LY] = "LY",
 49	[REG_LYC] = "LYC",
 50	[REG_DMA] = "DMA",
 51	[REG_BGP] = "BGP",
 52	[REG_OBP0] = "OBP0",
 53	[REG_OBP1] = "OBP1",
 54	[REG_WY] = "WY",
 55	[REG_WX] = "WX",
 56	[REG_KEY1] = "KEY1",
 57	[REG_VBK] = "VBK",
 58	[REG_HDMA1] = "HDMA1",
 59	[REG_HDMA2] = "HDMA2",
 60	[REG_HDMA3] = "HDMA3",
 61	[REG_HDMA4] = "HDMA4",
 62	[REG_HDMA5] = "HDMA5",
 63	[REG_RP] = "RP",
 64	[REG_BCPS] = "BCPS",
 65	[REG_BCPD] = "BCPD",
 66	[REG_OCPS] = "OCPS",
 67	[REG_OCPD] = "OCPD",
 68	[REG_SVBK] = "SVBK",
 69	[REG_IE] = "IE",
 70};
 71
 72static const uint8_t _registerMask[] = {
 73	[REG_SC]   = 0x7E, // TODO: GBC differences
 74	[REG_IF]   = 0xE0,
 75	[REG_TAC]  = 0xF8,
 76	[REG_NR10] = 0x80,
 77	[REG_NR11] = 0x3F,
 78	[REG_NR12] = 0x00,
 79	[REG_NR13] = 0xFF,
 80	[REG_NR14] = 0xBF,
 81	[REG_NR21] = 0x3F,
 82	[REG_NR22] = 0x00,
 83	[REG_NR23] = 0xFF,
 84	[REG_NR24] = 0xBF,
 85	[REG_NR30] = 0x7F,
 86	[REG_NR31] = 0xFF,
 87	[REG_NR32] = 0x9F,
 88	[REG_NR33] = 0xFF,
 89	[REG_NR34] = 0xBF,
 90	[REG_NR41] = 0xFF,
 91	[REG_NR42] = 0x00,
 92	[REG_NR43] = 0x00,
 93	[REG_NR44] = 0xBF,
 94	[REG_NR50] = 0x00,
 95	[REG_NR51] = 0x00,
 96	[REG_NR52] = 0x70,
 97	[REG_STAT] = 0x80,
 98	[REG_KEY1] = 0x7E,
 99	[REG_VBK] = 0xFE,
100	[REG_OCPS] = 0x40,
101	[REG_BCPS] = 0x40,
102	[REG_UNK6C] = 0xFE,
103	[REG_SVBK] = 0xF8,
104	[REG_IE]   = 0xE0,
105};
106
107static void _writeSGBBits(struct GB* gb, int bits) {
108	if (!bits) {
109		gb->sgbBit = -1;
110		memset(gb->sgbPacket, 0, sizeof(gb->sgbPacket));
111	}
112	if (bits == gb->currentSgbBits) {
113		return;
114	}
115	gb->currentSgbBits = bits;
116	if (gb->sgbBit == 128 && bits == 2) {
117		GBVideoWriteSGBPacket(&gb->video, gb->sgbPacket);
118		++gb->sgbBit;
119	}
120	if (gb->sgbBit >= 128) {
121		return;
122	}
123	switch (bits) {
124	case 1:
125		if (gb->sgbBit < 0) {
126			return;
127		}
128		gb->sgbPacket[gb->sgbBit >> 3] |= 1 << (gb->sgbBit & 7);
129		break;
130	case 3:
131		++gb->sgbBit;
132	default:
133		break;
134	}
135}
136
137void GBIOInit(struct GB* gb) {
138	memset(gb->memory.io, 0, sizeof(gb->memory.io));
139}
140
141void GBIOReset(struct GB* gb) {
142	memset(gb->memory.io, 0, sizeof(gb->memory.io));
143
144	GBIOWrite(gb, REG_TIMA, 0);
145	GBIOWrite(gb, REG_TMA, 0);
146	GBIOWrite(gb, REG_TAC, 0);
147	GBIOWrite(gb, REG_IF, 1);
148	GBIOWrite(gb, REG_NR52, 0xF1);
149	GBIOWrite(gb, REG_NR14, 0x3F);
150	GBIOWrite(gb, REG_NR10, 0x80);
151	GBIOWrite(gb, REG_NR11, 0xBF);
152	GBIOWrite(gb, REG_NR12, 0xF3);
153	GBIOWrite(gb, REG_NR13, 0xF3);
154	GBIOWrite(gb, REG_NR24, 0x3F);
155	GBIOWrite(gb, REG_NR21, 0x3F);
156	GBIOWrite(gb, REG_NR22, 0x00);
157	GBIOWrite(gb, REG_NR34, 0x3F);
158	GBIOWrite(gb, REG_NR30, 0x7F);
159	GBIOWrite(gb, REG_NR31, 0xFF);
160	GBIOWrite(gb, REG_NR32, 0x9F);
161	GBIOWrite(gb, REG_NR44, 0x3F);
162	GBIOWrite(gb, REG_NR41, 0xFF);
163	GBIOWrite(gb, REG_NR42, 0x00);
164	GBIOWrite(gb, REG_NR43, 0x00);
165	GBIOWrite(gb, REG_NR50, 0x77);
166	GBIOWrite(gb, REG_NR51, 0xF3);
167	GBIOWrite(gb, REG_LCDC, 0x91);
168	GBIOWrite(gb, REG_SCY, 0x00);
169	GBIOWrite(gb, REG_SCX, 0x00);
170	GBIOWrite(gb, REG_LYC, 0x00);
171	GBIOWrite(gb, REG_BGP, 0xFC);
172	if (gb->model < GB_MODEL_CGB) {
173		GBIOWrite(gb, REG_OBP0, 0xFF);
174		GBIOWrite(gb, REG_OBP1, 0xFF);
175	}
176	GBIOWrite(gb, REG_WY, 0x00);
177	GBIOWrite(gb, REG_WX, 0x00);
178	if (gb->model >= GB_MODEL_CGB) {
179		GBIOWrite(gb, REG_UNK4C, 0);
180		GBIOWrite(gb, REG_JOYP, 0xFF);
181		GBIOWrite(gb, REG_VBK, 0);
182		GBIOWrite(gb, REG_BCPS, 0);
183		GBIOWrite(gb, REG_OCPS, 0);
184		GBIOWrite(gb, REG_SVBK, 1);
185		GBIOWrite(gb, REG_HDMA1, 0xFF);
186		GBIOWrite(gb, REG_HDMA2, 0xFF);
187		GBIOWrite(gb, REG_HDMA3, 0xFF);
188		GBIOWrite(gb, REG_HDMA4, 0xFF);
189		gb->memory.io[REG_HDMA5] = 0xFF;
190	} else if (gb->model == GB_MODEL_SGB) {
191		GBIOWrite(gb, REG_JOYP, 0xFF);
192	}
193	GBIOWrite(gb, REG_IE, 0x00);
194}
195
196void GBIOWrite(struct GB* gb, unsigned address, uint8_t value) {
197	switch (address) {
198	case REG_SB:
199		GBSIOWriteSB(&gb->sio, value);
200		break;
201	case REG_SC:
202		GBSIOWriteSC(&gb->sio, value);
203		break;
204	case REG_DIV:
205		GBTimerDivReset(&gb->timer);
206		return;
207	case REG_NR10:
208		if (gb->audio.enable) {
209			GBAudioWriteNR10(&gb->audio, value);
210		} else {
211			value = 0;
212		}
213		break;
214	case REG_NR11:
215		if (gb->audio.enable) {
216			GBAudioWriteNR11(&gb->audio, value);
217		} else {
218			if (gb->audio.style == GB_AUDIO_DMG) {
219				GBAudioWriteNR11(&gb->audio, value & _registerMask[REG_NR11]);
220			}
221			value = 0;
222		}
223		break;
224	case REG_NR12:
225		if (gb->audio.enable) {
226			GBAudioWriteNR12(&gb->audio, value);
227		} else {
228			value = 0;
229		}
230		break;
231	case REG_NR13:
232		if (gb->audio.enable) {
233			GBAudioWriteNR13(&gb->audio, value);
234		} else {
235			value = 0;
236		}
237		break;
238	case REG_NR14:
239		if (gb->audio.enable) {
240			GBAudioWriteNR14(&gb->audio, value);
241		} else {
242			value = 0;
243		}
244		break;
245	case REG_NR21:
246		if (gb->audio.enable) {
247			GBAudioWriteNR21(&gb->audio, value);
248		} else {
249			if (gb->audio.style == GB_AUDIO_DMG) {
250				GBAudioWriteNR21(&gb->audio, value & _registerMask[REG_NR21]);
251			}
252			value = 0;
253		}
254		break;
255	case REG_NR22:
256		if (gb->audio.enable) {
257			GBAudioWriteNR22(&gb->audio, value);
258		} else {
259			value = 0;
260		}
261		break;
262	case REG_NR23:
263		if (gb->audio.enable) {
264			GBAudioWriteNR23(&gb->audio, value);
265		} else {
266			value = 0;
267		}
268		break;
269	case REG_NR24:
270		if (gb->audio.enable) {
271			GBAudioWriteNR24(&gb->audio, value);
272		} else {
273			value = 0;
274		}
275		break;
276	case REG_NR30:
277		if (gb->audio.enable) {
278			GBAudioWriteNR30(&gb->audio, value);
279		} else {
280			value = 0;
281		}
282		break;
283	case REG_NR31:
284		if (gb->audio.enable || gb->audio.style == GB_AUDIO_DMG) {
285			GBAudioWriteNR31(&gb->audio, value);
286		} else {
287			value = 0;
288		}
289		break;
290	case REG_NR32:
291		if (gb->audio.enable) {
292			GBAudioWriteNR32(&gb->audio, value);
293		} else {
294			value = 0;
295		}
296		break;
297	case REG_NR33:
298		if (gb->audio.enable) {
299			GBAudioWriteNR33(&gb->audio, value);
300		} else {
301			value = 0;
302		}
303		break;
304	case REG_NR34:
305		if (gb->audio.enable) {
306			GBAudioWriteNR34(&gb->audio, value);
307		} else {
308			value = 0;
309		}
310		break;
311	case REG_NR41:
312		if (gb->audio.enable || gb->audio.style == GB_AUDIO_DMG) {
313			GBAudioWriteNR41(&gb->audio, value);
314		} else {
315			value = 0;
316		}
317		break;
318	case REG_NR42:
319		if (gb->audio.enable) {
320			GBAudioWriteNR42(&gb->audio, value);
321		} else {
322			value = 0;
323		}
324		break;
325	case REG_NR43:
326		if (gb->audio.enable) {
327			GBAudioWriteNR43(&gb->audio, value);
328		} else {
329			value = 0;
330		}
331		break;
332	case REG_NR44:
333		if (gb->audio.enable) {
334			GBAudioWriteNR44(&gb->audio, value);
335		} else {
336			value = 0;
337		}
338		break;
339	case REG_NR50:
340		if (gb->audio.enable) {
341			GBAudioWriteNR50(&gb->audio, value);
342		} else {
343			value = 0;
344		}
345		break;
346	case REG_NR51:
347		if (gb->audio.enable) {
348			GBAudioWriteNR51(&gb->audio, value);
349		} else {
350			value = 0;
351		}
352		break;
353	case REG_NR52:
354		GBAudioWriteNR52(&gb->audio, value);
355		value &= 0x80;
356		value |= gb->memory.io[REG_NR52] & 0x0F;
357		break;
358	case REG_WAVE_0:
359	case REG_WAVE_1:
360	case REG_WAVE_2:
361	case REG_WAVE_3:
362	case REG_WAVE_4:
363	case REG_WAVE_5:
364	case REG_WAVE_6:
365	case REG_WAVE_7:
366	case REG_WAVE_8:
367	case REG_WAVE_9:
368	case REG_WAVE_A:
369	case REG_WAVE_B:
370	case REG_WAVE_C:
371	case REG_WAVE_D:
372	case REG_WAVE_E:
373	case REG_WAVE_F:
374		if (!gb->audio.playingCh3 || gb->audio.style != GB_AUDIO_DMG) {
375			gb->audio.ch3.wavedata8[address - REG_WAVE_0] = value;
376		} else if(gb->audio.ch3.readable) {
377			gb->audio.ch3.wavedata8[gb->audio.ch3.window >> 1] = value;
378		}
379		break;
380	case REG_JOYP:
381		if (gb->model == GB_MODEL_SGB) {
382			_writeSGBBits(gb, (value >> 4) & 3);
383		}
384		break;
385	case REG_TIMA:
386		if (value && mTimingUntil(&gb->timing, &gb->timer.irq) > 1) {
387			mTimingDeschedule(&gb->timing, &gb->timer.irq);
388		}
389		if (mTimingUntil(&gb->timing, &gb->timer.irq) == -1) {
390			return;
391		}
392		break;
393	case REG_TMA:
394		if (mTimingUntil(&gb->timing, &gb->timer.irq) == -1) {
395			gb->memory.io[REG_TIMA] = value;
396		}
397		break;
398	case REG_TAC:
399		value = GBTimerUpdateTAC(&gb->timer, value);
400		break;
401	case REG_IF:
402		gb->memory.io[REG_IF] = value | 0xE0;
403		GBUpdateIRQs(gb);
404		return;
405	case REG_LCDC:
406		// TODO: handle GBC differences
407		GBVideoProcessDots(&gb->video, 0);
408		value = gb->video.renderer->writeVideoRegister(gb->video.renderer, address, value);
409		GBVideoWriteLCDC(&gb->video, value);
410		break;
411	case REG_LYC:
412		GBVideoWriteLYC(&gb->video, value);
413		break;
414	case REG_DMA:
415		GBMemoryDMA(gb, value << 8);
416		break;
417	case REG_SCY:
418	case REG_SCX:
419	case REG_WY:
420	case REG_WX:
421		GBVideoProcessDots(&gb->video, 0);
422		value = gb->video.renderer->writeVideoRegister(gb->video.renderer, address, value);
423		break;
424	case REG_BGP:
425	case REG_OBP0:
426	case REG_OBP1:
427		GBVideoProcessDots(&gb->video, 0);
428		GBVideoWritePalette(&gb->video, address, value);
429		break;
430	case REG_STAT:
431		GBVideoWriteSTAT(&gb->video, value);
432		value = gb->video.stat;
433		break;
434	case 0x50:
435		GBUnmapBIOS(gb);
436		if (gb->model >= GB_MODEL_CGB && gb->memory.io[REG_UNK4C] < 0x80) {
437			gb->model = GB_MODEL_DMG;
438			GBVideoDisableCGB(&gb->video);
439		}
440		break;
441	case REG_IE:
442		gb->memory.ie = value;
443		GBUpdateIRQs(gb);
444		return;
445	default:
446		if (gb->model >= GB_MODEL_CGB) {
447			switch (address) {
448			case REG_UNK4C:
449				break;
450			case REG_KEY1:
451				value &= 0x1;
452				value |= gb->memory.io[address] & 0x80;
453				break;
454			case REG_VBK:
455				GBVideoSwitchBank(&gb->video, value);
456				break;
457			case REG_HDMA1:
458			case REG_HDMA2:
459			case REG_HDMA3:
460			case REG_HDMA4:
461				// Handled transparently by the registers
462				break;
463			case REG_HDMA5:
464				value = GBMemoryWriteHDMA5(gb, value);
465				break;
466			case REG_BCPS:
467				gb->video.bcpIndex = value & 0x3F;
468				gb->video.bcpIncrement = value & 0x80;
469				gb->memory.io[REG_BCPD] = gb->video.palette[gb->video.bcpIndex >> 1] >> (8 * (gb->video.bcpIndex & 1));
470				break;
471			case REG_BCPD:
472				GBVideoProcessDots(&gb->video, 0);
473				GBVideoWritePalette(&gb->video, address, value);
474				return;
475			case REG_OCPS:
476				gb->video.ocpIndex = value & 0x3F;
477				gb->video.ocpIncrement = value & 0x80;
478				gb->memory.io[REG_OCPD] = gb->video.palette[8 * 4 + (gb->video.ocpIndex >> 1)] >> (8 * (gb->video.ocpIndex & 1));
479				break;
480			case REG_OCPD:
481				GBVideoProcessDots(&gb->video, 0);
482				GBVideoWritePalette(&gb->video, address, value);
483				return;
484			case REG_SVBK:
485				GBMemorySwitchWramBank(&gb->memory, value);
486				value = gb->memory.wramCurrentBank;
487				break;
488			default:
489				goto failed;
490			}
491			goto success;
492		}
493		failed:
494		mLOG(GB_IO, STUB, "Writing to unknown register FF%02X:%02X", address, value);
495		if (address >= GB_SIZE_IO) {
496			return;
497		}
498		break;
499	}
500	success:
501	gb->memory.io[address] = value;
502}
503
504static uint8_t _readKeys(struct GB* gb) {
505	uint8_t keys = *gb->keySource;
506	switch (gb->memory.io[REG_JOYP] & 0x30) {
507	case 0x30:
508	// TODO: Increment
509		keys = (gb->video.sgbCommandHeader >> 3) == SGB_MLT_REG ? 0xF : 0;
510		break;
511	case 0x20:
512		keys >>= 4;
513		break;
514	case 0x10:
515		break;
516	case 0x00:
517		keys |= keys >> 4;
518		break;
519	}
520	return (0xC0 | (gb->memory.io[REG_JOYP] | 0xF)) ^ (keys & 0xF);
521}
522
523uint8_t GBIORead(struct GB* gb, unsigned address) {
524	switch (address) {
525	case REG_JOYP:
526		return _readKeys(gb);
527	case REG_IE:
528		return gb->memory.ie;
529	case REG_WAVE_0:
530	case REG_WAVE_1:
531	case REG_WAVE_2:
532	case REG_WAVE_3:
533	case REG_WAVE_4:
534	case REG_WAVE_5:
535	case REG_WAVE_6:
536	case REG_WAVE_7:
537	case REG_WAVE_8:
538	case REG_WAVE_9:
539	case REG_WAVE_A:
540	case REG_WAVE_B:
541	case REG_WAVE_C:
542	case REG_WAVE_D:
543	case REG_WAVE_E:
544	case REG_WAVE_F:
545		if (gb->audio.playingCh3) {
546			if (gb->audio.ch3.readable || gb->audio.style != GB_AUDIO_DMG) {
547				return gb->audio.ch3.wavedata8[gb->audio.ch3.window >> 1];
548			} else {
549				return 0xFF;
550			}
551		} else {
552			return gb->audio.ch3.wavedata8[address - REG_WAVE_0];
553		}
554		break;
555	case REG_SB:
556	case REG_SC:
557	case REG_IF:
558	case REG_NR10:
559	case REG_NR11:
560	case REG_NR12:
561	case REG_NR14:
562	case REG_NR21:
563	case REG_NR22:
564	case REG_NR24:
565	case REG_NR30:
566	case REG_NR32:
567	case REG_NR34:
568	case REG_NR41:
569	case REG_NR42:
570	case REG_NR43:
571	case REG_NR44:
572	case REG_NR50:
573	case REG_NR51:
574	case REG_NR52:
575	case REG_DIV:
576	case REG_TIMA:
577	case REG_TMA:
578	case REG_TAC:
579	case REG_STAT:
580	case REG_LCDC:
581	case REG_SCY:
582	case REG_SCX:
583	case REG_LY:
584	case REG_LYC:
585	case REG_BGP:
586	case REG_OBP0:
587	case REG_OBP1:
588	case REG_WY:
589	case REG_WX:
590		// Handled transparently by the registers
591		break;
592	default:
593		if (gb->model >= GB_MODEL_CGB) {
594			switch (address) {
595			case REG_KEY1:
596			case REG_VBK:
597			case REG_HDMA1:
598			case REG_HDMA2:
599			case REG_HDMA3:
600			case REG_HDMA4:
601			case REG_HDMA5:
602			case REG_BCPS:
603			case REG_BCPD:
604			case REG_OCPS:
605			case REG_OCPD:
606			case REG_SVBK:
607				// Handled transparently by the registers
608				goto success;
609			case REG_DMA:
610				mLOG(GB_IO, STUB, "Reading from unknown register FF%02X", address);
611				return 0;
612			default:
613				break;
614			}
615		}
616		mLOG(GB_IO, STUB, "Reading from unknown register FF%02X", address);
617		return 0xFF;
618	}
619	success:
620	return gb->memory.io[address] | _registerMask[address];
621}
622
623void GBTestKeypadIRQ(struct GB* gb) {
624	if (_readKeys(gb)) {
625		gb->memory.io[REG_IF] |= (1 << GB_IRQ_KEYPAD);
626		GBUpdateIRQs(gb);
627	}
628}
629
630struct GBSerializedState;
631void GBIOSerialize(const struct GB* gb, struct GBSerializedState* state) {
632	memcpy(state->io, gb->memory.io, GB_SIZE_IO);
633	state->ie = gb->memory.ie;
634}
635
636void GBIODeserialize(struct GB* gb, const struct GBSerializedState* state) {
637	memcpy(gb->memory.io, state->io, GB_SIZE_IO);
638	gb->memory.ie = state->ie;
639
640	if (GBAudioEnableGetEnable(*gb->audio.nr52)) {
641		GBIOWrite(gb, REG_NR10, gb->memory.io[REG_NR10]);
642		GBIOWrite(gb, REG_NR11, gb->memory.io[REG_NR11]);
643		GBIOWrite(gb, REG_NR12, gb->memory.io[REG_NR12]);
644		GBIOWrite(gb, REG_NR13, gb->memory.io[REG_NR13]);
645		gb->audio.ch1.control.frequency &= 0xFF;
646		gb->audio.ch1.control.frequency |= GBAudioRegisterControlGetFrequency(gb->memory.io[REG_NR14] << 8);
647		gb->audio.ch1.control.stop = GBAudioRegisterControlGetStop(gb->memory.io[REG_NR14] << 8);
648		GBIOWrite(gb, REG_NR21, gb->memory.io[REG_NR21]);
649		GBIOWrite(gb, REG_NR22, gb->memory.io[REG_NR22]);
650		GBIOWrite(gb, REG_NR22, gb->memory.io[REG_NR23]);
651		gb->audio.ch2.control.frequency &= 0xFF;
652		gb->audio.ch2.control.frequency |= GBAudioRegisterControlGetFrequency(gb->memory.io[REG_NR24] << 8);
653		gb->audio.ch2.control.stop = GBAudioRegisterControlGetStop(gb->memory.io[REG_NR24] << 8);
654		GBIOWrite(gb, REG_NR30, gb->memory.io[REG_NR30]);
655		GBIOWrite(gb, REG_NR31, gb->memory.io[REG_NR31]);
656		GBIOWrite(gb, REG_NR32, gb->memory.io[REG_NR32]);
657		GBIOWrite(gb, REG_NR32, gb->memory.io[REG_NR33]);
658		gb->audio.ch3.rate &= 0xFF;
659		gb->audio.ch3.rate |= GBAudioRegisterControlGetRate(gb->memory.io[REG_NR34] << 8);
660		gb->audio.ch3.stop = GBAudioRegisterControlGetStop(gb->memory.io[REG_NR34] << 8);
661		GBIOWrite(gb, REG_NR41, gb->memory.io[REG_NR41]);
662		GBIOWrite(gb, REG_NR42, gb->memory.io[REG_NR42]);
663		GBIOWrite(gb, REG_NR43, gb->memory.io[REG_NR43]);
664		gb->audio.ch4.stop = GBAudioRegisterNoiseControlGetStop(gb->memory.io[REG_NR44]);
665		GBIOWrite(gb, REG_NR50, gb->memory.io[REG_NR50]);
666		GBIOWrite(gb, REG_NR51, gb->memory.io[REG_NR51]);
667	}
668
669	gb->video.renderer->writeVideoRegister(gb->video.renderer, REG_LCDC, state->io[REG_LCDC]);
670	gb->video.renderer->writeVideoRegister(gb->video.renderer, REG_SCY, state->io[REG_SCY]);
671	gb->video.renderer->writeVideoRegister(gb->video.renderer, REG_SCX, state->io[REG_SCX]);
672	gb->video.renderer->writeVideoRegister(gb->video.renderer, REG_WY, state->io[REG_WY]);
673	gb->video.renderer->writeVideoRegister(gb->video.renderer, REG_WX, state->io[REG_WX]);
674	if (gb->model == GB_MODEL_SGB) {
675		gb->video.renderer->writeVideoRegister(gb->video.renderer, REG_BGP, state->io[REG_BGP]);
676		gb->video.renderer->writeVideoRegister(gb->video.renderer, REG_OBP0, state->io[REG_OBP0]);
677		gb->video.renderer->writeVideoRegister(gb->video.renderer, REG_OBP1, state->io[REG_OBP1]);
678	}
679	gb->video.stat = state->io[REG_STAT];
680}