Add an option to put the game on the Lower Screen.

* Before entering the menu, copy the game screen to the Upper Screen if it's on the Lower Screen.
* Now, the frame that's shown in the menu doesn't appear to be the previous frame for a fraction of a second anymore.

5 files changed, 86 insertions, 32 deletions

diff --git a/source/nds/displaymodes.cpp b/source/nds/displaymodes.cpp
index c45f7c1..ead3c93 100644
--- a/source/nds/displaymodes.cpp
+++ b/source/nds/displaymodes.cpp
@@ -56,10 +56,10 @@ static uint16 SevenToSixScanlineResize (uint16 TopColour, uint16 BottomColour, u
 	;
 }
 
-void NDSSFCDrawFrameAntialiased ()
+void NDSSFCDrawFrameAntialiased (void* screen_addr)
 {
 	uint16 X, Y;
-	uint16 *SrcTop = (uint16 *) GFX.Screen, *SrcBottom = SrcTop + 256, *Dest = (uint16 *) up_screen_addr;
+	uint16 *SrcTop = (uint16 *) GFX.Screen, *SrcBottom = SrcTop + 256, *Dest = (uint16 *) screen_addr;
 
 	for (Y = 0; Y < 224; Y += 7)
 	{
diff --git a/source/nds/entry.cpp b/source/nds/entry.cpp
index 456f078..1270d01 100644
--- a/source/nds/entry.cpp
+++ b/source/nds/entry.cpp
@@ -140,22 +140,29 @@ bool8 S9xInitUpdate ()
 }
 
 
-extern void NDSSFCDrawFrameAntialiased();
+extern void NDSSFCDrawFrameAntialiased(void* screen_addr);
 	
 
 bool8 S9xDeinitUpdate (int Width, int Height, bool8 /*sixteen_bit*/)
 {
+	void* screen_addr = emu_config.BottomScreenGame
+		? down_screen_addr
+		: up_screen_addr;
+	SCREEN_ID screen_num = emu_config.BottomScreenGame
+		? DOWN_SCREEN
+		: UP_SCREEN;
+
 	switch(game_config.graphic)
 	{
 		//Up
 		case 1:
 #ifdef DS2_DMA
 			__dcache_writeback_all();
-			ds2_DMAcopy_32Byte(1 /* channel: graphics */, up_screen_addr, GFX.Screen + 256 * 32 * 2, 256 * 192 * 2);
+			ds2_DMAcopy_32Byte(1 /* channel: graphics */, screen_addr, GFX.Screen + 256 * 32 * 2, 256 * 192 * 2);
 			ds2_DMA_wait(1);
 			ds2_DMA_stop(1);
 #else
-		    memcpy(up_screen_addr, GFX.Screen+256*32*2, 256*192*2);
+		    memcpy(screen_addr, GFX.Screen+256*32*2, 256*192*2);
 #endif
 			break;
 
@@ -163,11 +170,11 @@ bool8 S9xDeinitUpdate (int Width, int Height, bool8 /*sixteen_bit*/)
 		case 2:
 #ifdef DS2_DMA
 			__dcache_writeback_all();
-			ds2_DMAcopy_32Byte(1 /* channel: graphics */, up_screen_addr, GFX.Screen, 256 * 192 * 2);
+			ds2_DMAcopy_32Byte(1 /* channel: graphics */, screen_addr, GFX.Screen, 256 * 192 * 2);
 			ds2_DMA_wait(1);
 			ds2_DMA_stop(1);
 #else
-		    memcpy(up_screen_addr, GFX.Screen, 256*192*2);
+		    memcpy(screen_addr, GFX.Screen, 256*192*2);
 #endif
 			break;
 
@@ -175,16 +182,16 @@ bool8 S9xDeinitUpdate (int Width, int Height, bool8 /*sixteen_bit*/)
 		case 3:
 #ifdef DS2_DMA
 			__dcache_writeback_all();
-			ds2_DMAcopy_32Byte(1 /* channel: graphics */, up_screen_addr, GFX.Screen + 256 * 16 * 2, 256 * 192 * 2);
+			ds2_DMAcopy_32Byte(1 /* channel: graphics */, screen_addr, GFX.Screen + 256 * 16 * 2, 256 * 192 * 2);
 			ds2_DMA_wait(1);
 			ds2_DMA_stop(1);
 #else
-		    memcpy(up_screen_addr, GFX.Screen+256*16*2, 256*192*2);
+		    memcpy(screen_addr, GFX.Screen+256*16*2, 256*192*2);
 #endif
 			break;
 			
 		case 4:
-			NDSSFCDrawFrameAntialiased ();
+			NDSSFCDrawFrameAntialiased (screen_addr);
 		break;
 		
 
@@ -197,7 +204,7 @@ bool8 S9xDeinitUpdate (int Width, int Height, bool8 /*sixteen_bit*/)
 			register unsigned int m;
 
 			src = GFX.Screen;
-			dst = (unsigned char*)up_screen_addr;
+			dst = (unsigned char*)screen_addr;
 			for(m = 0; m < 32; m++)
 			{
 #ifdef DS2_DMA
@@ -214,7 +221,7 @@ bool8 S9xDeinitUpdate (int Width, int Height, bool8 /*sixteen_bit*/)
 			break;
 	}
 
-	ds2_flipScreen(UP_SCREEN, UP_SCREEN_UPDATE_METHOD);
+	ds2_flipScreen(screen_num, UP_SCREEN_UPDATE_METHOD);
 	// A problem with update method 1 (wait, double buffer) means that, after
 	// about 15 minutes of play time, the screen starts to half-redraw every
 	// frame. With update method 0, this is mitigated. (Method 2 is too slow.)
@@ -648,7 +655,19 @@ int sfc_main (int argc, char **argv)
 				S9xSetSoundMute (TRUE);
 				unsigned short screen[256*192];
 
-				copy_screen((void*)screen, up_screen_addr, 0, 0, 256, 192);
+				if (FirstInvocation) {
+					memset(screen, 0, sizeof(screen));
+				}
+				else {
+					S9xDeinitUpdate(256, 224, TRUE);
+
+					void* screen_addr = emu_config.BottomScreenGame
+						? down_screen_addr
+						: up_screen_addr;
+
+					copy_screen((void*)screen, screen_addr, 0, 0, 256, 192);
+				}
+
 				menu(screen, FirstInvocation);
 				FirstInvocation = FALSE;
 				game_disableAudio();
@@ -1262,10 +1281,13 @@ uint32 S9xReadJoypad (int which1)
 				mdelay(1);
 			} while (inputdata.key & KEY_LID);
 			ds2_wakeup();
-			// Before starting to emulate again, turn off the lower
-			// screen's backlight.
+			// Before starting to emulate again, turn on only the
+			// game screen's backlight.
+			SCREEN_ID screen_num = emu_config.BottomScreenGame
+				? DOWN_SCREEN
+				: UP_SCREEN;
 			mdelay(100); // needed to avoid ds2_setBacklight crashing
-			ds2_setBacklight(2);
+			ds2_setBacklight(3 - screen_num);
 			GameFrequencyCPU();
 		}
 
diff --git a/source/nds/gui.c b/source/nds/gui.c
index ca5a016..4b9c129 100644
--- a/source/nds/gui.c
+++ b/source/nds/gui.c
@@ -2728,6 +2728,9 @@ u32 menu(u16 *screen, bool8 FirstInvocation)
 
     char *sound_seletion[] = { (char*)&msg[MSG_AUDIO_MUTED], (char*)&msg[MSG_AUDIO_ENABLED] };
 
+    char *game_screen_options[] = { (char*)&msg[MSG_VIDEO_GAME_SCREEN_TOP], (char*)&msg[MSG_VIDEO_GAME_SCREEN_BOTTOM] };
+
+
 //    char *snap_frame_options[] = { (char*)&msg[MSG_SNAP_FRAME_0], (char*)&msg[MSG_SNAP_FRAME_1] };
 
 //    char *enable_disable_options[] = { (char*)&msg[MSG_EN_DIS_ABLE_0], (char*)&msg[MSG_EN_DIS_ABLE_1] };
@@ -2755,7 +2758,11 @@ u32 menu(u16 *screen, bool8 FirstInvocation)
 		&game_config.frameskip_value, 12 /* auto (0) and 0..10 (1..11) make 12 option values */, NULL, ACTION_TYPE, 5),
 
 	/* 06 */	STRING_SELECTION_OPTION(game_set_retro, NULL, &msg[FMT_AUDIO_RETRO_SOUND], on_off_options,
-		&game_config.RetroSound, 2, NULL, ACTION_TYPE, 6)
+		&game_config.RetroSound, 2, NULL, ACTION_TYPE, 6),
+
+	/* 07 */	STRING_SELECTION_OPTION(NULL, NULL, &msg[FMT_VIDEO_GAME_SCREEN], game_screen_options,
+		&emu_config.BottomScreenGame, 2, NULL, PASSIVE_TYPE, 7)
+
 	};
 
 	MAKE_MENU(graphics, NULL, NULL, NULL, NULL, 1, 1);
@@ -3569,12 +3576,9 @@ u32 menu(u16 *screen, bool8 FirstInvocation)
 	}
 	else
 	{
-		/*
-		 * It's pretty complicated. These two flips are needed because,
-		 * otherwise, the menu freezes if S9xAutoSaveSRAM was called after
-		 * loading from a save state.
-		 */
+		copy_screen(up_screen_addr, (void*) screen, 0, 0, 256, 192);
 		ds2_flipScreen(UP_SCREEN, 1);
+		copy_screen(up_screen_addr, (void*) screen, 0, 0, 256, 192);
 		ds2_flipScreen(UP_SCREEN, 1);
 	}
 
@@ -4022,14 +4026,31 @@ u32 menu(u16 *screen, bool8 FirstInvocation)
 
 	if(bg_screenp != NULL) free((void*)bg_screenp);
 
-	ds2_clearScreen(DOWN_SCREEN, 0);
-	ds2_flipScreen(DOWN_SCREEN, DOWN_SCREEN_UPDATE_METHOD);
-	copy_screen(up_screen_addr, (void*) screen, 0, 0, 256, 192);
-	ds2_flipScreen(UP_SCREEN, UP_SCREEN_UPDATE_METHOD);
+	void* screen_addr;
+	SCREEN_ID screen_num;
+	if (emu_config.BottomScreenGame)
+	{
+		screen_addr = down_screen_addr;
+		screen_num = DOWN_SCREEN;
+		ds2_clearScreen(UP_SCREEN, 0);
+		ds2_flipScreen(UP_SCREEN, DOWN_SCREEN_UPDATE_METHOD);
+	}
+	else
+	{
+		screen_addr = up_screen_addr;
+		screen_num = UP_SCREEN;
+		ds2_clearScreen(DOWN_SCREEN, 0);
+		ds2_flipScreen(DOWN_SCREEN, DOWN_SCREEN_UPDATE_METHOD);
+	}
+
+	copy_screen(screen_addr, (void*) screen, 0, 0, 256, 192);
+	ds2_flipScreen(screen_num, UP_SCREEN_UPDATE_METHOD);
+	copy_screen(screen_addr, (void*) screen, 0, 0, 256, 192);
+	ds2_flipScreen(screen_num, UP_SCREEN_UPDATE_METHOD);
 	wait_Allkey_release(0);
 
 	mdelay(100); // to prevent ds2_setBacklight() from crashing
-	ds2_setBacklight(2);
+	ds2_setBacklight(3 - screen_num);
 
 	GameFrequencyCPU();
 
@@ -4623,9 +4644,12 @@ void QuickLoadState (void)
 {
 	char BaseName[MAX_PATH + 1];
 	get_savestate_filename(0, BaseName);
+	SCREEN_ID screen_num = emu_config.BottomScreenGame
+		? DOWN_SCREEN
+		: UP_SCREEN;
 
 	mdelay(100); // needed to avoid ds2_setBacklight crashing
-	ds2_setBacklight(3);
+	ds2_setBacklight((3 - DOWN_SCREEN) | (3 - screen_num));
 
 	ds2_clearScreen(DOWN_SCREEN, RGB15(0, 0, 0));
 	draw_message(down_screen_addr, NULL, 28, 31, 227, 165, 0);
@@ -4647,16 +4671,19 @@ void QuickLoadState (void)
 	ds2_flipScreen(DOWN_SCREEN, DOWN_SCREEN_UPDATE_METHOD);
 
 	mdelay(100); // needed to avoid ds2_setBacklight crashing
-	ds2_setBacklight(2);
+	ds2_setBacklight(3 - screen_num);
 }
 
 void QuickSaveState (void)
 {
 	char BaseName[MAX_PATH + 1];
 	get_savestate_filename(0, BaseName);
+	SCREEN_ID screen_num = emu_config.BottomScreenGame
+		? DOWN_SCREEN
+		: UP_SCREEN;
 
 	mdelay(100); // needed to avoid ds2_setBacklight crashing
-	ds2_setBacklight(3);
+	ds2_setBacklight((3 - DOWN_SCREEN) | (3 - screen_num));
 
 	ds2_clearScreen(DOWN_SCREEN, RGB15(0, 0, 0));
 	draw_message(down_screen_addr, NULL, 28, 31, 227, 165, 0);
@@ -4680,7 +4707,7 @@ void QuickSaveState (void)
 	ds2_flipScreen(DOWN_SCREEN, DOWN_SCREEN_UPDATE_METHOD);
 
 	mdelay(100); // needed to avoid ds2_setBacklight crashing
-	ds2_setBacklight(2);
+	ds2_setBacklight(3 - screen_num);
 }
 
 void ToggleFullScreen (void)
diff --git a/source/nds/gui.h b/source/nds/gui.h
index 570afe6..980553b 100644
--- a/source/nds/gui.h
+++ b/source/nds/gui.h
@@ -86,7 +86,8 @@ struct _EMU_CONFIG
   u32 HotkeyQuickLoadState;
   u32 HotkeyQuickSaveState;
   u32 HotkeyToggleFullScreen;
-  u32 Reserved[58];
+  u32 BottomScreenGame;
+  u32 Reserved[57];
 };
 
 struct _GAME_CONFIG
diff --git a/source/nds/message.h b/source/nds/message.h
index 07799ec..98f64ab 100644
--- a/source/nds/message.h
+++ b/source/nds/message.h
@@ -37,6 +37,7 @@ enum MSG
 	FMT_VIDEO_ASPECT_RATIO,
 	FMT_VIDEO_FAST_FORWARD,
 	FMT_VIDEO_FRAME_SKIPPING,
+	FMT_VIDEO_GAME_SCREEN,
 	FMT_AUDIO_SOUND,
 	FMT_AUDIO_RETRO_SOUND,
 	FMT_SAVED_STATE_CREATE,
@@ -92,6 +93,9 @@ enum MSG
 	MSG_VIDEO_FRAME_SKIPPING_9,
 	MSG_VIDEO_FRAME_SKIPPING_10,
 
+	MSG_VIDEO_GAME_SCREEN_TOP,
+	MSG_VIDEO_GAME_SCREEN_BOTTOM,
+
 	MSG_GENERAL_OFF,
 	MSG_GENERAL_ON,