Core: Add support for caching bitmapped modes

CHANGES

@@ -7,6 +7,7 @@ Features:
  - GB: Expose platform information to CLI debugger
  - Support Discord Rich Presence
  - Debugger: Add tracing to file
+ - Map viewer supports bitmapped GBA modes
 Emulation fixes:
  - GBA: All IRQs have 7 cycle delay (fixes mgba.io/i/539, mgba.io/i/1208)
  - GBA: Reset now reloads multiboot ROMs

include/mgba/core/bitmap-cache.h

@@ -0,0 +1,64 @@
+/* Copyright (c) 2013-2019 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#ifndef M_BITMAP_CACHE_H
+#define M_BITMAP_CACHE_H
+
+#include <mgba-util/common.h>
+
+CXX_GUARD_START
+
+#include <mgba/core/interface.h>
+
+DECL_BITFIELD(mBitmapCacheConfiguration, uint32_t);
+DECL_BIT(mBitmapCacheConfiguration, ShouldStore, 0);
+
+DECL_BITFIELD(mBitmapCacheSystemInfo, uint32_t);
+DECL_BITS(mBitmapCacheSystemInfo, EntryBPP, 0, 3);
+DECL_BIT(mBitmapCacheSystemInfo, UsesPalette, 3);
+DECL_BITS(mBitmapCacheSystemInfo, Width, 4, 10);
+DECL_BITS(mBitmapCacheSystemInfo, Height, 14, 10);
+DECL_BITS(mBitmapCacheSystemInfo, Buffers, 24, 2);
+
+struct mBitmapCacheEntry {
+	uint32_t paletteVersion;
+	uint32_t vramVersion;
+	uint8_t vramClean;
+};
+
+struct mBitmapCache {
+	color_t* cache;
+	struct mBitmapCacheEntry* status;
+
+	uint32_t globalPaletteVersion;
+
+	uint8_t* vram;
+	color_t* palette;
+
+	uint32_t bitsSize;
+	uint32_t bitsStart[2];
+	uint32_t stride;
+	uint8_t buffer;
+
+	mBitmapCacheConfiguration config;
+	mBitmapCacheSystemInfo sysConfig;
+
+	void* context;
+};
+
+void mBitmapCacheInit(struct mBitmapCache* cache);
+void mBitmapCacheDeinit(struct mBitmapCache* cache);
+void mBitmapCacheConfigure(struct mBitmapCache* cache, mBitmapCacheConfiguration config);
+void mBitmapCacheConfigureSystem(struct mBitmapCache* cache, mBitmapCacheSystemInfo config);
+void mBitmapCacheWriteVRAM(struct mBitmapCache* cache, uint32_t address);
+void mBitmapCacheWritePalette(struct mBitmapCache* cache, uint32_t entry, color_t color);
+
+void mBitmapCacheCleanRow(struct mBitmapCache* cache, struct mBitmapCacheEntry* entry, unsigned y);
+bool mBitmapCacheCheckRow(struct mBitmapCache* cache, const struct mBitmapCacheEntry* entry, unsigned y);
+const color_t* mBitmapCacheGetRow(struct mBitmapCache* cache, unsigned y);
+
+CXX_GUARD_END
+
+#endif

include/mgba/core/cache-set.h

@@ -10,19 +10,22 @@
 
 CXX_GUARD_START
 
+#include <mgba/core/bitmap-cache.h>
 #include <mgba/core/map-cache.h>
 #include <mgba/core/tile-cache.h>
 #include <mgba-util/vector.h>
 
 DECLARE_VECTOR(mMapCacheSet, struct mMapCache);
+DECLARE_VECTOR(mBitmapCacheSet, struct mBitmapCache);
 DECLARE_VECTOR(mTileCacheSet, struct mTileCache);
 
 struct mCacheSet {
 	struct mMapCacheSet maps;
+	struct mBitmapCacheSet bitmaps;
 	struct mTileCacheSet tiles;
 };
 
-void mCacheSetInit(struct mCacheSet*, size_t nMaps, size_t nTiles);
+void mCacheSetInit(struct mCacheSet*, size_t nMaps, size_t nBitmaps, size_t nTiles);
 void mCacheSetDeinit(struct mCacheSet*);
 
 void mCacheSetAssignVRAM(struct mCacheSet*, void* vram);

src/core/bitmap-cache.c

@@ -0,0 +1,182 @@
+/* Copyright (c) 2013-2019 Jeffrey Pfau
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+#include <mgba/core/bitmap-cache.h>
+
+#include <mgba-util/memory.h>
+
+void mBitmapCacheInit(struct mBitmapCache* cache) {
+	// TODO: Reconfigurable cache for space savings
+	cache->cache = NULL;
+	cache->config = mBitmapCacheConfigurationFillShouldStore(0);
+	cache->status = NULL;
+	cache->palette = NULL;
+	cache->buffer = 0;
+}
+
+static void _freeCache(struct mBitmapCache* cache) {
+	size_t size = mBitmapCacheSystemInfoGetHeight(cache->sysConfig) * mBitmapCacheSystemInfoGetBuffers(cache->sysConfig);
+	mappedMemoryFree(cache->cache, mBitmapCacheSystemInfoGetWidth(cache->sysConfig) * size * sizeof(color_t));
+	mappedMemoryFree(cache->status, size * sizeof(*cache->status));
+	if (cache->palette) {
+		free(cache->palette);
+	}
+	cache->cache = NULL;
+	cache->status = NULL;
+	cache->palette = NULL;
+}
+
+static void _redoCacheSize(struct mBitmapCache* cache) {
+	if (!mBitmapCacheConfigurationIsShouldStore(cache->config)) {
+		return;
+	}
+
+	size_t size = mBitmapCacheSystemInfoGetHeight(cache->sysConfig) * mBitmapCacheSystemInfoGetBuffers(cache->sysConfig);
+	cache->cache = anonymousMemoryMap(mBitmapCacheSystemInfoGetWidth(cache->sysConfig) * size * sizeof(color_t));
+	cache->status = anonymousMemoryMap(size * sizeof(*cache->status));
+	if (mBitmapCacheSystemInfoIsUsesPalette(cache->sysConfig)) {
+		cache->palette = malloc((1 << (1 << mBitmapCacheSystemInfoGetEntryBPP(cache->sysConfig))) * sizeof(color_t));
+	} else {
+		cache->palette = NULL;
+	}
+}
+
+void mBitmapCacheConfigure(struct mBitmapCache* cache, mBitmapCacheConfiguration config) {
+	if (config == cache->config) {
+		return;
+	}
+	_freeCache(cache);
+	cache->config = config;
+	_redoCacheSize(cache);
+}
+
+void mBitmapCacheConfigureSystem(struct mBitmapCache* cache, mBitmapCacheSystemInfo config) {
+	if (config == cache->sysConfig) {
+		return;
+	}
+	_freeCache(cache);
+	cache->sysConfig = config;
+	_redoCacheSize(cache);
+
+	size_t stride = mBitmapCacheSystemInfoGetWidth(cache->sysConfig);
+	size_t size = stride * mBitmapCacheSystemInfoGetHeight(cache->sysConfig);
+	size_t bpe = mBitmapCacheSystemInfoGetEntryBPP(cache->sysConfig);
+	if (bpe > 3) {
+		size <<= bpe - 3;
+		stride <<= bpe - 3;
+	} else {
+		size >>= 3 - bpe;
+		stride >>= 3 - bpe;
+	}
+	cache->bitsSize = size;
+	cache->stride = stride;
+}
+
+void mBitmapCacheDeinit(struct mBitmapCache* cache) {
+	_freeCache(cache);
+}
+
+void mBitmapCacheWriteVRAM(struct mBitmapCache* cache, uint32_t address) {
+	size_t i;
+	for (i = 0; i < mBitmapCacheSystemInfoGetBuffers(cache->sysConfig); ++i) {
+		if (address < cache->bitsStart[i]) {
+			continue;
+		}
+		uint32_t offset = address - cache->bitsStart[i];
+		if (offset >= cache->bitsSize) {
+			continue;
+		}
+		offset /= cache->stride;
+		offset *= mBitmapCacheSystemInfoGetBuffers(cache->sysConfig);
+		offset += cache->buffer;
+		cache->status[offset].vramClean = 0;
+		++cache->status[offset].vramVersion;
+	}
+}
+
+void mBitmapCacheWritePalette(struct mBitmapCache* cache, uint32_t entry, color_t color) {
+	if (!mBitmapCacheSystemInfoIsUsesPalette(cache->sysConfig)) {
+		return;
+	}
+	size_t maxEntry = 1 << (1 << mBitmapCacheSystemInfoGetEntryBPP(cache->sysConfig));
+	if (entry >= maxEntry) {
+		return;
+	}
+	cache->palette[entry] = color;
+	++cache->globalPaletteVersion;
+}
+
+uint32_t _lookupEntry8(void* vram, uint32_t offset) {
+	return ((uint8_t*) vram)[offset];
+}
+
+uint32_t _lookupEntry15(void* vram, uint32_t offset) {
+	return mColorFrom555(((uint16_t*) vram)[offset]);
+}
+
+void mBitmapCacheCleanRow(struct mBitmapCache* cache, struct mBitmapCacheEntry* entry, unsigned y) {
+	color_t* row = &cache->cache[(cache->buffer * mBitmapCacheSystemInfoGetHeight(cache->sysConfig) + y) * mBitmapCacheSystemInfoGetWidth(cache->sysConfig)];
+	size_t location = cache->buffer + mBitmapCacheSystemInfoGetBuffers(cache->sysConfig) * y;
+	struct mBitmapCacheEntry* status = &cache->status[location];
+	struct mBitmapCacheEntry desiredStatus = {
+		.paletteVersion = cache->globalPaletteVersion,
+		.vramVersion = entry->vramVersion,
+		.vramClean = 1
+	};
+
+	if (entry) {
+		entry[location] = desiredStatus;
+	}
+
+	if (!mBitmapCacheConfigurationIsShouldStore(cache->config) || !memcmp(status, &desiredStatus, sizeof(*entry))) {
+		return;
+	}
+
+	size_t offset = cache->bitsStart[cache->buffer] + y * mBitmapCacheSystemInfoGetWidth(cache->sysConfig);
+	void* vram;
+	int bpe = mBitmapCacheSystemInfoGetEntryBPP(cache->sysConfig);
+	uint32_t (*lookupEntry)(void*, uint32_t);
+	switch (bpe) {
+	case 3:
+		lookupEntry = _lookupEntry8;
+		vram = &cache->vram[offset];
+		break;
+	case 4:
+		lookupEntry = _lookupEntry15;
+		vram = &cache->vram[offset << 1];
+		break;
+	default:
+		abort();
+		break;
+	}
+
+	size_t x;
+	if (mBitmapCacheSystemInfoIsUsesPalette(cache->sysConfig)) {
+		for (x = 0; x < mBitmapCacheSystemInfoGetWidth(cache->sysConfig); ++x) {
+			row[x] = cache->palette[lookupEntry(vram, x)];
+		}
+	} else {
+		for (x = 0; x < mBitmapCacheSystemInfoGetWidth(cache->sysConfig); ++x) {
+			row[x] = lookupEntry(vram, x);
+		}
+	}
+	*status = desiredStatus;
+}
+
+bool mBitmapCacheCheckRow(struct mBitmapCache* cache, const struct mBitmapCacheEntry* entry, unsigned y) {
+	size_t location = cache->buffer + mBitmapCacheSystemInfoGetBuffers(cache->sysConfig) * y;
+	struct mBitmapCacheEntry desiredStatus = {
+		.paletteVersion = cache->globalPaletteVersion,
+		.vramVersion = entry->vramVersion,
+		.vramClean = 1
+	};
+
+	return memcmp(&entry[location], &desiredStatus, sizeof(*entry)) == 0;
+}
+
+const color_t* mBitmapCacheGetRow(struct mBitmapCache* cache, unsigned y) {
+	color_t* row = &cache->cache[(cache->buffer * mBitmapCacheSystemInfoGetHeight(cache->sysConfig) + y) * mBitmapCacheSystemInfoGetWidth(cache->sysConfig)];
+	return row;
+}

src/core/cache-set.c

@@ -6,11 +6,14 @@
 #include <mgba/core/cache-set.h>
 
 DEFINE_VECTOR(mMapCacheSet, struct mMapCache);
+DEFINE_VECTOR(mBitmapCacheSet, struct mBitmapCache);
 DEFINE_VECTOR(mTileCacheSet, struct mTileCache);
 
-void mCacheSetInit(struct mCacheSet* cache, size_t nMaps, size_t nTiles) {
+void mCacheSetInit(struct mCacheSet* cache, size_t nMaps, size_t nBitmaps, size_t nTiles) {
 	mMapCacheSetInit(&cache->maps, nMaps);
 	mMapCacheSetResize(&cache->maps, nMaps);
+	mBitmapCacheSetInit(&cache->bitmaps, nBitmaps);
+	mBitmapCacheSetResize(&cache->bitmaps, nBitmaps);
 	mTileCacheSetInit(&cache->tiles, nTiles);
 	mTileCacheSetResize(&cache->tiles, nTiles);
 
@@ -18,6 +21,9 @@ void mCacheSetInit(struct mCacheSet* cache, size_t nMaps, size_t nTiles) {
 	for (i = 0; i < nMaps; ++i) {
 		mMapCacheInit(mMapCacheSetGetPointer(&cache->maps, i));
 	}
+	for (i = 0; i < nBitmaps; ++i) {
+		mBitmapCacheInit(mBitmapCacheSetGetPointer(&cache->bitmaps, i));
+	}
 	for (i = 0; i < nTiles; ++i) {
 		mTileCacheInit(mTileCacheSetGetPointer(&cache->tiles, i));
 	}
@@ -28,6 +34,9 @@ void mCacheSetDeinit(struct mCacheSet* cache) {
 	for (i = 0; i < mMapCacheSetSize(&cache->maps); ++i) {
 		mMapCacheDeinit(mMapCacheSetGetPointer(&cache->maps, i));
 	}
+	for (i = 0; i < mBitmapCacheSetSize(&cache->bitmaps); ++i) {
+		mBitmapCacheDeinit(mBitmapCacheSetGetPointer(&cache->bitmaps, i));
+	}
 	for (i = 0; i < mTileCacheSetSize(&cache->tiles); ++i) {
 		mTileCacheDeinit(mTileCacheSetGetPointer(&cache->tiles, i));
 	}
@@ -38,6 +47,9 @@ void mCacheSetAssignVRAM(struct mCacheSet* cache, void* vram) {
 	for (i = 0; i < mMapCacheSetSize(&cache->maps); ++i) {
 		mMapCacheSetGetPointer(&cache->maps, i)->vram = vram;
 	}
+	for (i = 0; i < mBitmapCacheSetSize(&cache->bitmaps); ++i) {
+		mBitmapCacheSetGetPointer(&cache->bitmaps, i)->vram = vram;
+	}
 	for (i = 0; i < mTileCacheSetSize(&cache->tiles); ++i) {
 		struct mTileCache* tileCache = mTileCacheSetGetPointer(&cache->tiles, i);
 		tileCache->vram = (void*) ((uintptr_t) vram + tileCache->tileBase);
@@ -49,6 +61,9 @@ void mCacheSetWriteVRAM(struct mCacheSet* cache, uint32_t address) {
 	for (i = 0; i < mMapCacheSetSize(&cache->maps); ++i) {
 		mMapCacheWriteVRAM(mMapCacheSetGetPointer(&cache->maps, i), address);
 	}
+	for (i = 0; i < mBitmapCacheSetSize(&cache->bitmaps); ++i) {
+		mBitmapCacheWriteVRAM(mBitmapCacheSetGetPointer(&cache->bitmaps, i), address);
+	}
 	for (i = 0; i < mTileCacheSetSize(&cache->tiles); ++i) {
 		mTileCacheWriteVRAM(mTileCacheSetGetPointer(&cache->tiles, i), address);
 	}
@@ -56,6 +71,9 @@ void mCacheSetWriteVRAM(struct mCacheSet* cache, uint32_t address) {
 
 void mCacheSetWritePalette(struct mCacheSet* cache, uint32_t entry, color_t color) {
 	size_t i;
+	for (i = 0; i < mBitmapCacheSetSize(&cache->bitmaps); ++i) {
+		mBitmapCacheWritePalette(mBitmapCacheSetGetPointer(&cache->bitmaps, i), entry, color);
+	}
 	for (i = 0; i < mTileCacheSetSize(&cache->tiles); ++i) {
 		mTileCacheWritePalette(mTileCacheSetGetPointer(&cache->tiles, i), entry, color);
 	}

src/gb/renderers/cache-set.c

@@ -11,16 +11,13 @@
 #include <mgba/internal/gb/video.h>
 
 void GBVideoCacheInit(struct mCacheSet* cache) {
-	mCacheSetInit(cache, 2, 1);
+	mCacheSetInit(cache, 2, 0, 1);
 	mTileCacheConfiguration config = 0;
 	config = mTileCacheSystemInfoSetPaletteBPP(config, 1); // 2^(2^1) = 4 entries
 	config = mTileCacheSystemInfoSetPaletteCount(config, 4); // 16 palettes
 	config = mTileCacheSystemInfoSetMaxTiles(config, 1024);
-	mTileCacheInit(mTileCacheSetGetPointer(&cache->tiles, 0));
 	mTileCacheConfigureSystem(mTileCacheSetGetPointer(&cache->tiles, 0), config, 0, 0);
 
-	mMapCacheInit(mMapCacheSetGetPointer(&cache->maps, 0));
-	mMapCacheInit(mMapCacheSetGetPointer(&cache->maps, 1));
 	mMapCacheSetGetPointer(&cache->maps, 0)->tileCache = mTileCacheSetGetPointer(&cache->tiles, 0);
 	mMapCacheSetGetPointer(&cache->maps, 1)->tileCache = mTileCacheSetGetPointer(&cache->tiles, 0);
 }

src/gba/renderers/cache-set.c

@@ -11,35 +11,45 @@
 #include <mgba/internal/gba/video.h>
 
 void GBAVideoCacheInit(struct mCacheSet* cache) {
-	mCacheSetInit(cache, 4, 4);
+	mCacheSetInit(cache, 4, 2, 4);
 	mTileCacheSystemInfo sysconfig = 0;
 	mTileCacheConfiguration config = mTileCacheConfigurationFillShouldStore(0);
 	sysconfig = mTileCacheSystemInfoSetPaletteBPP(sysconfig, 2); // 2^(2^2) = 16 entries
 	sysconfig = mTileCacheSystemInfoSetPaletteCount(sysconfig, 4); // 16 palettes
 	sysconfig = mTileCacheSystemInfoSetMaxTiles(sysconfig, 2048);
-	mTileCacheInit(mTileCacheSetGetPointer(&cache->tiles, 0));
 	mTileCacheConfigure(mTileCacheSetGetPointer(&cache->tiles, 0), config);
 	mTileCacheConfigureSystem(mTileCacheSetGetPointer(&cache->tiles, 0), sysconfig, 0, 0);
 	sysconfig = mTileCacheSystemInfoSetMaxTiles(sysconfig, 1024);
-	mTileCacheInit(mTileCacheSetGetPointer(&cache->tiles, 2));
 	mTileCacheConfigure(mTileCacheSetGetPointer(&cache->tiles, 2), config);
 	mTileCacheConfigureSystem(mTileCacheSetGetPointer(&cache->tiles, 2), sysconfig, 0x10000, 0x100);
 
 	sysconfig = mTileCacheSystemInfoSetPaletteBPP(sysconfig, 3); // 2^(2^3) = 256 entries
 	sysconfig = mTileCacheSystemInfoSetPaletteCount(sysconfig, 0); // 1 palettes
 	sysconfig = mTileCacheSystemInfoSetMaxTiles(sysconfig, 2048);
-	mTileCacheInit(mTileCacheSetGetPointer(&cache->tiles, 1));
 	mTileCacheConfigure(mTileCacheSetGetPointer(&cache->tiles, 1), config);
 	mTileCacheConfigureSystem(mTileCacheSetGetPointer(&cache->tiles, 1), sysconfig, 0, 0);
 	sysconfig = mTileCacheSystemInfoSetMaxTiles(sysconfig, 1024);
-	mTileCacheInit(mTileCacheSetGetPointer(&cache->tiles, 3));
 	mTileCacheConfigure(mTileCacheSetGetPointer(&cache->tiles, 3), config);
 	mTileCacheConfigureSystem(mTileCacheSetGetPointer(&cache->tiles, 3), sysconfig, 0x10000, 0x100);
 
-	mMapCacheInit(mMapCacheSetGetPointer(&cache->maps, 0));
+	mBitmapCacheSystemInfo bitConfig;
-	mMapCacheInit(mMapCacheSetGetPointer(&cache->maps, 1));
+	bitConfig = mBitmapCacheSystemInfoSetEntryBPP(0, 4);
-	mMapCacheInit(mMapCacheSetGetPointer(&cache->maps, 2));
+	bitConfig = mBitmapCacheSystemInfoClearUsesPalette(bitConfig);
-	mMapCacheInit(mMapCacheSetGetPointer(&cache->maps, 3));
+	bitConfig = mBitmapCacheSystemInfoSetHeight(bitConfig, 160);
+	bitConfig = mBitmapCacheSystemInfoSetWidth(bitConfig, 240);
+	bitConfig = mBitmapCacheSystemInfoSetBuffers(bitConfig, 1);
+	mBitmapCacheConfigureSystem(mBitmapCacheSetGetPointer(&cache->bitmaps, 0), bitConfig);
+	mBitmapCacheSetGetPointer(&cache->bitmaps, 0)->bitsStart[0] = 0;
+	mBitmapCacheSetGetPointer(&cache->bitmaps, 0)->bitsStart[1] = 0xA000;
+
+	bitConfig = mBitmapCacheSystemInfoSetEntryBPP(0, 3);
+	bitConfig = mBitmapCacheSystemInfoFillUsesPalette(bitConfig);
+	bitConfig = mBitmapCacheSystemInfoSetHeight(bitConfig, 160);
+	bitConfig = mBitmapCacheSystemInfoSetWidth(bitConfig, 240);
+	bitConfig = mBitmapCacheSystemInfoSetBuffers(bitConfig, 2);
+	mBitmapCacheConfigureSystem(mBitmapCacheSetGetPointer(&cache->bitmaps, 1), bitConfig);
+	mBitmapCacheSetGetPointer(&cache->bitmaps, 1)->bitsStart[0] = 0;
+	mBitmapCacheSetGetPointer(&cache->bitmaps, 1)->bitsStart[1] = 0xA000;
 }
 
 void GBAVideoCacheAssociate(struct mCacheSet* cache, struct GBAVideo* video) {
@@ -77,6 +87,8 @@ static void mapParser2(struct mMapCache* cache, struct mMapCacheEntry* entry, vo
 }
 
 static void GBAVideoCacheWriteDISPCNT(struct mCacheSet* cache, uint16_t value) {
+	mBitmapCacheSetGetPointer(&cache->bitmaps, 1)->buffer = GBARegisterDISPCNTGetFrameSelect(value);
+
 	switch (GBARegisterDISPCNTGetMode(value)) {
 	case 0:
 	default:
@@ -110,6 +122,28 @@ static void GBAVideoCacheWriteDISPCNT(struct mCacheSet* cache, uint16_t value) {
 		mMapCacheSetGetPointer(&cache->maps, 3)->tileCache = mTileCacheSetGetPointer(&cache->tiles, 1);
 		break;
 	}
+
+	mBitmapCacheSystemInfo bitConfig;
+	switch (GBARegisterDISPCNTGetMode(value)) {
+	case 3:
+		bitConfig = mBitmapCacheSystemInfoSetEntryBPP(0, 4);
+		bitConfig = mBitmapCacheSystemInfoClearUsesPalette(bitConfig);
+		bitConfig = mBitmapCacheSystemInfoSetHeight(bitConfig, 160);
+		bitConfig = mBitmapCacheSystemInfoSetWidth(bitConfig, 240);
+		bitConfig = mBitmapCacheSystemInfoSetBuffers(bitConfig, 1);
+		mBitmapCacheConfigureSystem(mBitmapCacheSetGetPointer(&cache->bitmaps, 0), bitConfig);
+		mBitmapCacheSetGetPointer(&cache->bitmaps, 0)->buffer = 0;
+		break;
+	case 5:
+		bitConfig = mBitmapCacheSystemInfoSetEntryBPP(0, 4);
+		bitConfig = mBitmapCacheSystemInfoClearUsesPalette(bitConfig);
+		bitConfig = mBitmapCacheSystemInfoSetHeight(bitConfig, 128);
+		bitConfig = mBitmapCacheSystemInfoSetWidth(bitConfig, 160);
+		bitConfig = mBitmapCacheSystemInfoSetBuffers(bitConfig, 2);
+		mBitmapCacheConfigureSystem(mBitmapCacheSetGetPointer(&cache->bitmaps, 0), bitConfig);
+		mBitmapCacheSetGetPointer(&cache->bitmaps, 0)->buffer = GBARegisterDISPCNTGetFrameSelect(value);
+		break;
+	}
 }
 
 static void GBAVideoCacheWriteBGCNT(struct mCacheSet* cache, size_t bg, uint16_t value) {

src/platform/qt/MapView.cpp

@@ -12,7 +12,10 @@
 #include <mgba-util/png-io.h>
 #include <mgba-util/vfs.h>
 #ifdef M_CORE_GBA
+#include <mgba/internal/gba/gba.h>
+#include <mgba/internal/gba/io.h>
 #include <mgba/internal/gba/memory.h>
+#include <mgba/internal/gba/video.h>
 #endif
 #ifdef M_CORE_GB
 #include <mgba/internal/gb/memory.h>
@@ -139,6 +142,24 @@ bool MapView::eventFilter(QObject* obj, QEvent* event) {
 void MapView::updateTilesGBA(bool force) {
 	{
 		CoreController::Interrupter interrupter(m_controller);
+		int bitmap = -1;
+		if (m_controller->platform() == PLATFORM_GBA) {
+			int mode = GBARegisterDISPCNTGetMode(static_cast<GBA*>(m_controller->thread()->core->board)->memory.io[REG_DISPCNT]);
+			if (m_map == 2 && mode > 2) {
+				bitmap = mode == 4 ? 1 : 0;
+			}
+		}
+		if (bitmap >= 0) {
+			mBitmapCache* bitmapCache = mBitmapCacheSetGetPointer(&m_cacheSet->bitmaps, bitmap);
+			int width = mBitmapCacheSystemInfoGetWidth(bitmapCache->sysConfig);
+			int height = mBitmapCacheSystemInfoGetHeight(bitmapCache->sysConfig);
+			m_rawMap = QImage(QSize(width, height), QImage::Format_ARGB32);
+			uchar* bgBits = m_rawMap.bits();
+			for (int j = 0; j < height; ++j) {
+				mBitmapCacheCleanRow(bitmapCache, m_bitmapStatus, j);
+				memcpy(static_cast<void*>(&bgBits[width * j * 4]), mBitmapCacheGetRow(bitmapCache, j), width * 4);
+			}
+		} else {
 			mMapCache* mapCache = mMapCacheSetGetPointer(&m_cacheSet->maps, m_map);
 			int tilesW = 1 << mMapCacheSystemInfoGetTilesWide(mapCache->sysConfig);
 			int tilesH = 1 << mMapCacheSystemInfoGetTilesHigh(mapCache->sysConfig);
@@ -153,6 +174,7 @@ void MapView::updateTilesGBA(bool force) {
 				}
 			}
 		}
+	}
 	m_rawMap = m_rawMap.rgbSwapped();
 	QPixmap map = QPixmap::fromImage(m_rawMap.convertToFormat(QImage::Format_RGB32));
 	if (m_ui.magnification->value() > 1) {
@@ -181,7 +203,6 @@ void MapView::exportMap() {
 	png_structp png = PNGWriteOpen(vf);
 	png_infop info = PNGWriteHeaderA(png, m_rawMap.width(), m_rawMap.height());
 
-	mMapCache* mapCache = mMapCacheSetGetPointer(&m_cacheSet->maps, m_map);
 	QImage map = m_rawMap.rgbSwapped();
 	PNGWritePixelsA(png, map.width(), map.height(), map.bytesPerLine() / 4, static_cast<const void*>(map.constBits()));
 	PNGWriteClose(png, info);

src/platform/qt/MapView.h

@@ -45,6 +45,7 @@ private:
 
 	std::shared_ptr<CoreController> m_controller;
 	mMapCacheEntry m_mapStatus[128 * 128] = {}; // TODO: Correct size
+	mBitmapCacheEntry m_bitmapStatus[512 * 2] = {}; // TODO: Correct size
 	int m_map = 0;
 	QImage m_rawMap;
 	int m_boundary;