Add support for user-selected and automatic frame skipping. Add support for PAL timings (20 ms per frame).

User-selected frameskip causes slowdowns if the game runs slower than the resulting frame rate, but synchronises correctly if the game runs faster.

Automatic frame skipping is still the default. It now only skips up to 8 frames, but in some games still skips that entire 8 frames. What's needed is an algorithm that averages frame latencies over a few seconds and skips while the latency is LOWER than the average.

7 files changed, 227 insertions, 149 deletions

diff --git a/source/cheats.h b/source/cheats.h
index bb2646f..2f3252e 100644
--- a/source/cheats.h
+++ b/source/cheats.h
@@ -102,7 +102,7 @@ struct SCheat
     uint8   byte;
     uint8   saved_byte;
     // bool8   enabled;
-	uint32	enabled; // THIS IS A TOTAL HACK FOR THE NDSSFC GUI, YOU HAVE BEEN WARNED [Neb]
+	u32	enabled; // THIS IS A TOTAL HACK FOR THE NDSSFC GUI, YOU HAVE BEEN WARNED [Neb]
     bool8   saved;
     char    name[MAX_SFCCHEAT_NAME];
 };
diff --git a/source/cpuexec.cpp b/source/cpuexec.cpp
index 66bb8da..b90da6d 100644
--- a/source/cpuexec.cpp
+++ b/source/cpuexec.cpp
@@ -330,81 +330,6 @@ void S9xDoHBlankProcessing ()
 				Snapshot (NULL);
 			}
 #endif
-			if(!game_fast_forward)
-			{
-				syncnow = getSysTime();
-				if(syncnow > sync_next)
-				{
-					/*
-					 * Little bit of a hack here:
-					 * If we get behind and stay behind for a certain number
-					 * of frames, we automatically enable fast forward.
-					 * That really helps with certain games, such as
-					 * Super Mario RPG and Yoshi's Island.
-					 */
-					if(skip_rate++ < 10)
-					{
-						syncdif = syncnow - sync_next;
-						if(syncdif < 11718)
-						{
-							IPPU.RenderThisFrame = false;
-							sync_next += 391;
-						}
-						else
-						{	//lag more than 0.5s, maybe paused
-							IPPU.RenderThisFrame = true;
-							sync_next = syncnow;
-							framenum = 0;
-							sync_last = syncnow;
-							realframe = 1;
-						}
-					}
-					else
-					{
-						skip_rate = 0;
-						IPPU.RenderThisFrame = true;
-						sync_last= syncnow;
-						sync_next = syncnow+391;
-					}
-				}
-				else
-				{
-					skip_rate = 0;
-					syncdif = sync_next - syncnow;
-					if(syncdif > 391)
-					{
-						udelay(syncdif*22);
-						S9xProcessSound (0);
-					}
-
-					IPPU.RenderThisFrame = true;
-					sync_next += 391;	//16.7ms
-					realframe += 1;
-				}
-#if 0
-				if(++framenum >= 60)
-				{
-					syncdif = syncnow - sync_last;
-					sync_last = syncnow;
-					framenum = 0;
-					//printf("T %d %d\n", syncdif*42667/1000, realframe);
-					realframe = 0;
-				}
-#endif
-			} 
-			else
-			{
-				sync_last= 0;
-				sync_next = 0;
-
-				if(skip_rate++ < 10)
-					IPPU.RenderThisFrame = false;
-				else
-				{
-					skip_rate = 0;
-					IPPU.RenderThisFrame = true;
-				}
-			}
 		}
 
 		if (CPU.V_Counter == PPU.ScreenHeight + 3)
diff --git a/source/nds/entry.cpp b/source/nds/entry.cpp
index 5573f47..58adf49 100644
--- a/source/nds/entry.cpp
+++ b/source/nds/entry.cpp
@@ -343,6 +343,18 @@ void game_disableAudio()
 		S9xSetSoundMute (TRUE);
 	}
 }
+
+void game_set_frameskip()
+{
+	if( game_config.frameskip_value == 0)
+	{
+		Settings.SkipFrames = AUTO_FRAMERATE;
+	}
+	else
+	{
+		Settings.SkipFrames = game_config.frameskip_value - 1 /* 1 -> 0 and so on */;
+	}
+}
 	
 void init_sfc_setting(void)
 {
@@ -368,7 +380,6 @@ void init_sfc_setting(void)
     Settings.ShutdownMaster = TRUE;
     Settings.FrameTimePAL = 20000;
     Settings.FrameTimeNTSC = 16667;
-    Settings.FrameTime = Settings.FrameTimeNTSC;
     Settings.DisableSampleCaching = FALSE;
     Settings.DisableMasterVolume = FALSE;
     Settings.Mouse = TRUE;
@@ -449,10 +460,12 @@ int load_gamepak(char* file)
 	game_disableAudio();
 
 	CPU.Flags = 0;
-	S9xReset ();
 	// mdelay(50); // Delete this delay
 	if (!Memory.LoadROM (file))
 		return -1;
+	S9xReset ();
+
+	Settings.FrameTime = (Settings.PAL ? Settings.FrameTimePAL : Settings.FrameTimeNTSC);
 
 	Memory.LoadSRAM (S9xGetFilename (".srm"));
 	// mdelay(50); // Delete this delay
@@ -611,41 +624,18 @@ int sfc_main (int argc, char **argv)
     return (0);
 }
 
+static unsigned int sync_last= 0;
+static unsigned int sync_next = 0;
+static unsigned int framenum = 0;
+
+extern "C" u32 game_fast_forward;
+
+static unsigned int skip_rate= 0;
+
 void S9xSyncSpeed ()
 {
-#if 0
-#ifdef _NETPLAY_SUPPORT
-    if (Settings.NetPlay)
-    {
-	// XXX: Send joypad position update to server
-	// XXX: Wait for heart beat from server
-	S9xNetPlaySendJoypadUpdate (joypads [0]);
-	if (!S9xNetPlayCheckForHeartBeat ())
-	{
-	    do
-	    {
-		CHECK_SOUND ();
-//		S9xProcessEvents (FALSE);
-	    } while (!S9xNetPlayCheckForHeartBeat ());
-	    IPPU.RenderThisFrame = TRUE;
-	    IPPU.SkippedFrames = 0;
-	}
-	else
-	{
-	    if (IPPU.SkippedFrames < 10)
-	    {
-		IPPU.SkippedFrames++;
-		IPPU.RenderThisFrame = FALSE;
-	    }
-	    else
-	    {
-		IPPU.RenderThisFrame = TRUE;
-		IPPU.SkippedFrames = 0;
-	    }
-	}
-    }
-    else
-#endif
+	uint32 syncnow;
+	int32 syncdif;
 
 #if 0
     if (Settings.SoundSync == 2)
@@ -655,30 +645,135 @@ void S9xSyncSpeed ()
 	return;
     }
 #endif
+	syncnow = getSysTime();
+
+	if (game_fast_forward)
+	{
+		sync_last = syncnow;
+		sync_next = syncnow;
 
+		if(++skip_rate < 10)
+			IPPU.RenderThisFrame = false;
+		else
+		{
+			skip_rate = 0;
+			IPPU.RenderThisFrame = true;
+		}
+	}
+	else if (Settings.SkipFrames == AUTO_FRAMERATE /* && !game_fast_forward */)
+	{
+		// frame_time is in getSysTime units: 42.667 microseconds.
+		uint32 frame_time = Settings.PAL ? 468 /* = 20.0 ms */ : 391 /* = 16.67 ms */;
+		if (sync_last > syncnow) // Overflow occurred! (every 50 hrs)
+		{
+			// Render this frame regardless, set the
+			// sync_next, and get the hell out.
+			IPPU.RenderThisFrame = TRUE;
+			sync_last = syncnow;
+			sync_next = syncnow + frame_time;
+			return;
+		}
+		sync_last = syncnow;
+		// If this is positive, we have syncdif*42.66 microseconds to
+		// spare.
+		// If this is negative, we're late by syncdif*42.66
+		// microseconds.
+		syncdif = sync_next - syncnow;
+		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
+			// skipped.
+			skip_rate = 0;
+			IPPU.RenderThisFrame = true;
+			sync_next += frame_time;
+		}
+		else if(syncdif < 0)
+		{
+			/*
+			 * If we're consistently late, delay up to 8 frames.
+			 * 
+			 * That really helps with certain games, such as
+			 * Super Mario RPG and Yoshi's Island.
+			 */
+			if(++skip_rate < 10)
+			{
+				if(syncdif >= -11719 /* not more than 500.0 ms late */)
+				{
+					IPPU.RenderThisFrame = FALSE;
+					sync_next += frame_time;
+				}
+				else
+				{	//lag more than 0.5s, maybe paused
+					IPPU.RenderThisFrame = TRUE;
+					sync_next = syncnow + frame_time;
+					framenum = 0;
+				}
+			}
+			else
+			{
+				skip_rate = 0;
+				IPPU.RenderThisFrame = TRUE;
+				sync_next = syncnow + frame_time;
+			}
+		}
+		else // Early
+		{
+			skip_rate = 0;
+			ds2_setCPUclocklevel(0);
+			if (syncdif > 0)
+				udelay(syncdif * 128 / 3 /* times 42 + 2/3 microseconds */);
+			set_cpu_clock(clock_speed_number);
+			S9xProcessSound (0);
+
+			IPPU.RenderThisFrame = TRUE;
+			sync_next += frame_time;
+		}
 #if 0
-    if (Settings.TurboMode)
-    {
-        if(++IPPU.FrameSkip >= Settings.TurboSkipFrames)
-        {
-            IPPU.FrameSkip = 0;
-            IPPU.SkippedFrames = 0;
-            IPPU.RenderThisFrame = TRUE;
-        }
-        else
-        {
-            ++IPPU.SkippedFrames;
-            IPPU.RenderThisFrame = FALSE;
-        }
-        return;
-    }
+		if(++framenum >= 60)
+		{
+			syncdif = syncnow - sync_last;
+			sync_last = syncnow;
+			framenum = 0;
+			//printf("T %d %d\n", syncdif*42667/1000, realframe);
+			realframe = 0;
+		}
 #endif
+	}
+	else /* if (Settings.SkipFrames != AUTO_FRAMERATE && !game_fast_forward) */
+	{
+		// frame_time is in getSysTime units: 42.667 microseconds.
+		uint32 frame_time = Settings.PAL ? 468 /* = 20.0 ms */ : 391 /* = 16.67 ms */;
+		sync_last = syncnow;
+		if (++skip_rate > Settings.SkipFrames)
+		{
+			skip_rate = 0;
+			IPPU.RenderThisFrame = TRUE;
+			// Are we early?
+			syncdif = sync_next - syncnow;
+			if (syncdif > 0)
+			{
+				ds2_setCPUclocklevel(0);
+				udelay(syncdif * 128 / 3 /* times 42 + 2/3 microseconds */);
+				set_cpu_clock(clock_speed_number);
+				S9xProcessSound (0);
+				// After that little delay, what time is it?
+				syncnow = getSysTime();
+			}
+			sync_next = syncnow + frame_time * Settings.SkipFrames;
+		}
+		else
+		{
+			IPPU.RenderThisFrame = FALSE;
+		}
+	}
 
 #ifdef __sgi
     /* BS: saves on CPU usage */
     sginap(1);
 #endif
 
+#if 0
     /* Check events */
     
     static struct timeval next1 = {0, 0};
diff --git a/source/nds/gui.c b/source/nds/gui.c
index 4ebb224..d198166 100644
--- a/source/nds/gui.c
+++ b/source/nds/gui.c
@@ -17,8 +17,8 @@
  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  */
 
+#include "snes9x.h"
 
- 
 #include <stdio.h>
 #include <string.h>
 #include <sys/stat.h>
@@ -78,7 +78,7 @@ GAME_CONFIG game_config;
 
 //save state file map
 char savestate_map[SAVE_STATE_SLOT_NUM];
-static unsigned int savestate_index;
+static u32 savestate_index;
 
 #define MAKE_MENU(name, init_function, passive_function, key_function, end_function, \
 	focus_option, screen_focus)												  \
@@ -2776,7 +2776,7 @@ u32 menu(u16 *screen)
 									(char*)&msg[MSG_VIDEO_ASPECT_RATIO_3],
 									(char*)&msg[MSG_VIDEO_ASPECT_RATIO_4]};
     
-    char *frameskip_options[] = { (char*)&msg[MSG_FRAMESKIP_0], (char*)&msg[MSG_FRAMESKIP_1] };
+    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 *on_off_options[] = { (char*)&msg[MSG_GENERAL_OFF], (char*)&msg[MSG_GENERAL_ON] };
 
@@ -2800,7 +2800,10 @@ u32 menu(u16 *screen)
 		&game_fast_forward, 2, NULL, ACTION_TYPE, 2),
 		
 	/* 03 */	STRING_SELECTION_OPTION(game_disableAudio, NULL, &msg[FMT_AUDIO_SOUND], sound_seletion,
-		&game_enable_audio, 2, NULL, ACTION_TYPE, 3)
+		&game_enable_audio, 2, NULL, ACTION_TYPE, 3),
+		
+	/* 04 */	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, 4)
 	};
 
 	MAKE_MENU(graphics, NULL, NULL, NULL, NULL, 0, 0);
@@ -4004,9 +4007,7 @@ void init_game_config(void)
 	game_config.clock_speed_number = 5;	// 396 MHz by default
 	clock_speed_number = 5;
 	game_config.graphic = 3; // By default, have a good-looking aspect ratio
-
-	game_config.gamepad_config_menu = BUTTON_ID_TOUCH;
-    memcpy(game_config.gamepad_config_map, gamepad_config_map_init, sizeof(gamepad_config_map_init));
+	game_config.frameskip_value = 0; // Automatic frame skipping
 
 	game_config.backward = 0;	//time backward disable
 	game_config.backward_time = 2;	//time backward granularity 1s
@@ -4063,9 +4064,8 @@ void load_game_config_file(void)
 	{
 		fread(&game_config, 1, sizeof(GAME_CONFIG), fp);
 
-		memcpy(gamepad_config_map, game_config.gamepad_config_map, sizeof(game_config.gamepad_config_map));
-		gamepad_config_menu = game_config.gamepad_config_menu;
 		clock_speed_number = game_config.clock_speed_number;
+		Settings.SkipFrames = (game_config.frameskip_value == 0 ? AUTO_FRAMERATE : game_config.frameskip_value - 1 /* 1 -> 0 and so on */);
 	}
 
 	fclose(fp);
@@ -4113,9 +4113,6 @@ int save_game_config_file(void)
 
     if(gamepak_name[0] == 0) return -1;
 
-    memcpy(game_config.gamepad_config_map, gamepad_config_map, sizeof(game_config.gamepad_config_map));
-    game_config.gamepad_config_menu = gamepad_config_menu;
-
     sprintf(game_config_filename, "%s/%s", DEFAULT_CFG_DIR, gamepak_name);
     pt = strrchr(game_config_filename, '.');
 	if(NULL == pt) 
diff --git a/source/nds/gui.h b/source/nds/gui.h
index 5a40979..ec0dd1a 100644
--- a/source/nds/gui.h
+++ b/source/nds/gui.h
@@ -44,16 +44,63 @@ struct _EMU_CONFIG
 
 struct _GAME_CONFIG
 {
-	u32	clock_speed_number;
-	u32 frameskip_type;
+	u32 clock_speed_number;
+	u32  Reserved0;
 	u32 frameskip_value;
-	u32	graphic;
-	u32	enable_audio;
-	u32 gamepad_config_menu;
+	u32 graphic;
+	u32 enable_audio;
+	u32 Reserved1;
 	u32 backward;
 	u32 backward_time;
-	u32	reserve[32];
-	u32 gamepad_config_map[MAX_GAMEPAD_MAP];
+	u32  Reserved2;
+	u32  Reserved3;
+	u32  Reserved4;
+	u32  Reserved5;
+	u32  Reserved6;
+	u32  Reserved7;
+	u32  Reserved8;
+	u32  Reserved9;
+	u32  Reserved10;
+	u32  Reserved11;
+	u32  Reserved12;
+	u32  Reserved13;
+	u32  Reserved14;
+	u32  Reserved15;
+	u32  Reserved16;
+	u32  Reserved17;
+	u32  Reserved18;
+	u32  Reserved19;
+	u32  Reserved20;
+	u32  Reserved21;
+	u32  Reserved22;
+	u32  Reserved23;
+	u32  Reserved24;
+	u32  Reserved25;
+	u32  Reserved26;
+	u32  Reserved27;
+	u32  Reserved28;
+	u32  Reserved29;
+	u32  Reserved30;
+	u32  Reserved31;
+	u32  Reserved32;
+
+	u32  Reserved33;
+	u32  Reserved34;
+	u32  Reserved35;
+	u32  Reserved36;
+	u32  Reserved37;
+	u32  Reserved38;
+	u32  Reserved39;
+	u32  Reserved40;
+	u32  Reserved41;
+	u32  Reserved42;
+	u32  Reserved43;
+	u32  Reserved44;
+	u32  Reserved45;
+	u32  Reserved46;
+	u32  Reserved47;
+	u32  Reserved48;
+	u32  Reserved49;
 };
 
 typedef enum
@@ -118,6 +165,7 @@ extern GAME_CONFIG	game_config;
 extern void gui_init(u32 lang_id);
 extern u32 menu(u16 *original_screen);
 extern void game_disableAudio();
+extern void game_set_frameskip();
 extern void set_cpu_clock(u32 num);
 
 #ifdef __cplusplus
diff --git a/source/nds/message.h b/source/nds/message.h
index ee89acd..09332bc 100644
--- a/source/nds/message.h
+++ b/source/nds/message.h
@@ -30,8 +30,7 @@ enum MSG
 	MSG_MAIN_MENU_EXIT,
 	FMT_VIDEO_ASPECT_RATIO,
 	FMT_VIDEO_FAST_FORWARD,
-	FMT_VIDEO_FRAME_SKIP_AUTOMATIC,
-	FMT_VIDEO_FRAME_SKIP_MANUAL,
+	FMT_VIDEO_FRAME_SKIPPING,
 	FMT_AUDIO_SOUND,
 	MSG_SAVED_STATE_CREATE,
 	FMT_SAVED_STATE_LOAD,
@@ -56,8 +55,18 @@ enum MSG
 	MSG_VIDEO_ASPECT_RATIO_3,
 	MSG_VIDEO_ASPECT_RATIO_4,
 
-	MSG_FRAMESKIP_0,                  // currently unused
-	MSG_FRAMESKIP_1,                  // currently unused
+	MSG_VIDEO_FRAME_SKIPPING_AUTOMATIC,
+	MSG_VIDEO_FRAME_SKIPPING_0,
+	MSG_VIDEO_FRAME_SKIPPING_1,
+	MSG_VIDEO_FRAME_SKIPPING_2,
+	MSG_VIDEO_FRAME_SKIPPING_3,
+	MSG_VIDEO_FRAME_SKIPPING_4,
+	MSG_VIDEO_FRAME_SKIPPING_5,
+	MSG_VIDEO_FRAME_SKIPPING_6,
+	MSG_VIDEO_FRAME_SKIPPING_7,
+	MSG_VIDEO_FRAME_SKIPPING_8,
+	MSG_VIDEO_FRAME_SKIPPING_9,
+	MSG_VIDEO_FRAME_SKIPPING_10,
 
 	MSG_GENERAL_OFF,
 	MSG_GENERAL_ON,
diff --git a/source/snes9x.h b/source/snes9x.h
index e9ed479..e9e29b8 100644
--- a/source/snes9x.h
+++ b/source/snes9x.h
@@ -97,9 +97,13 @@
 #include "fs_api.h"
 #include "ds2_malloc.h"
 
+#ifdef __cplusplus
 extern "C" {
+#endif
 extern int cprintf(const char *fmt, ...);
+#ifdef __cplusplus
 }
+#endif
 
 #ifdef __WIN32__
 #include "..\wsnes9x.h"