Force both manual and automatic frameskipping to be at or above 2. Resets the default value for all games which previously had this value configured.

4 files changed, 35 insertions, 9 deletions

diff --git a/source/nds/entry.cpp b/source/nds/entry.cpp
index 18802a0..6cbf3ef 100644
--- a/source/nds/entry.cpp
+++ b/source/nds/entry.cpp
@@ -390,7 +390,7 @@ void game_set_frameskip()
 	}
 	else
 	{
-		Settings.SkipFrames = game_config.frameskip_value - 1 /* 1 -> 0 and so on */;
+		Settings.SkipFrames = game_config.frameskip_value + 1 /* 1 -> 2 and so on */;
 	}
 }
 
@@ -639,7 +639,6 @@ int sfc_main (int argc, char **argv)
 
 static unsigned int sync_last= 0;
 static unsigned int sync_next = 0;
-static unsigned int auto_equivalent_skip = 0;
 
 static unsigned int skip_rate= 0;
 
@@ -690,7 +689,16 @@ void S9xSyncSpeed ()
 		// If this is negative, we're late by syncdif*42.66
 		// microseconds.
 		syncdif = sync_next - syncnow;
-		if (syncdif < 0 && syncdif >= -(frame_time / 2))
+		if(skip_rate < 2 /* did not skip 2 frames yet */)
+		{
+			// Skip a minimum of 2 frames between rendered frames.
+			// This prevents the DSTwo-DS link from being too busy
+			// to return button statuses.
+			++skip_rate;
+			IPPU.RenderThisFrame = FALSE;
+			sync_next += frame_time;
+		}
+		else if (syncdif < 0 && syncdif >= -(frame_time / 2))
 		{
 			// We're late, but by less than half a frame. Draw it
 			// anyway. If the next frame is too late, it'll be
diff --git a/source/nds/gui.c b/source/nds/gui.c
index 764ca66..4b5955a 100644
--- a/source/nds/gui.c
+++ b/source/nds/gui.c
@@ -2826,7 +2826,7 @@ u32 menu(u16 *screen, bool8 FirstInvocation)
 									(char*)&msg[MSG_VIDEO_ASPECT_RATIO_3],
 									(char*)&msg[MSG_VIDEO_ASPECT_RATIO_4]};
     
-    char *frameskip_options[] = { (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_AUTOMATIC], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_0], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_1], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_2], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_3], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_4], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_5], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_6], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_7], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_8], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_9], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_10] };
+    char *frameskip_options[] = { (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_AUTOMATIC], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_2], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_3], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_4], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_5], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_6], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_7], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_8], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_9], (char*)&msg[MSG_VIDEO_FRAME_SKIPPING_10] };
 
     char *fluidity_options[] = { (char*)&msg[MSG_VIDEO_AUDIO_FLUIDITY_PREFER_VIDEO], (char*)&msg[MSG_VIDEO_AUDIO_FLUIDITY_PREFER_AUDIO] };
 
@@ -2858,7 +2858,7 @@ u32 menu(u16 *screen, bool8 FirstInvocation)
 		&game_config.SoundSync, 2, NULL, ACTION_TYPE, 4),
 		
 	/* 05 */	STRING_SELECTION_OPTION(game_set_frameskip, NULL, &msg[FMT_VIDEO_FRAME_SKIPPING], frameskip_options,
-		&game_config.frameskip_value, 12 /* auto (0) and 0..10 (1..11) make 12 option values */, NULL, ACTION_TYPE, 5)
+		&game_config.frameskip_value, 10 /* auto (0) and 2..10 (1..9) make 10 option values */, NULL, ACTION_TYPE, 5)
 	};
 
 	MAKE_MENU(graphics, NULL, NULL, NULL, NULL, 0, 0);
diff --git a/source/nds/gui.h b/source/nds/gui.h
index e8302eb..b390b69 100644
--- a/source/nds/gui.h
+++ b/source/nds/gui.h
@@ -50,7 +50,24 @@ struct _GAME_CONFIG
 {
 	u32 clock_speed_number;
 	u32  Reserved0;
-	u32 frameskip_value;
+	/*
+	 * PreviouslyUsed_20130205_1 was formerly known as 'frameskip_value';
+	 * its values were in [0, 10]. 0 was automatic frameskipping and
+	 * [1, 10] were mapped to skip 0 to 9 frames respectively.
+	 * Version 1.29 changes the value range for 'frameskip_value' to
+	 * [0, 8], with 0 as automatic frameskipping and [1, 10] to skip 2 to
+	 * 9 frames.
+	 * Change rationale: Frame skip values under 2 cause too much
+	 * communication between the DSTwo and the DS, therefore the DS cannot
+	 * timely send controller information.
+	 * If this variable were to be used as is, the meaning of the option
+	 * would be changed for values in [1, 8], and values in [9, 10] would
+	 * cause undefined behavior, including crashes.
+	 * THIS VALUE IS NOT GUARANTEED TO BE RESERVED AND SET TO 0.
+	 * DO NOT USE THIS VALUE FOR ANY PURPOSE OTHER THAN EXACTLY THE ONE
+	 * FOR WHICH IT WAS INTENDED.
+	 */
+	u32 PreviouslyUsed_20130205_1;
 	u32 graphic;
 	u32 enable_audio;
 	u32 Reserved1;
@@ -60,7 +77,8 @@ struct _GAME_CONFIG
 	u32 HotkeyTemporaryFastForward;
 	u32 HotkeyToggleSound;
 	u32 SoundSync;
-	u32  Reserved2[44];
+	u32 frameskip_value;
+	u32  Reserved2[43];
 };
 
 typedef enum
diff --git a/source/nds/message.h b/source/nds/message.h
index b5bb47b..86389b1 100644
--- a/source/nds/message.h
+++ b/source/nds/message.h
@@ -70,8 +70,8 @@ enum MSG
 	MSG_VIDEO_ASPECT_RATIO_4,
 
 	MSG_VIDEO_FRAME_SKIPPING_AUTOMATIC,
-	MSG_VIDEO_FRAME_SKIPPING_0,
-	MSG_VIDEO_FRAME_SKIPPING_1,
+	MSG_VIDEO_FRAME_SKIPPING_0 /* unused */,
+	MSG_VIDEO_FRAME_SKIPPING_1 /* unused */,
 	MSG_VIDEO_FRAME_SKIPPING_2,
 	MSG_VIDEO_FRAME_SKIPPING_3,
 	MSG_VIDEO_FRAME_SKIPPING_4,