syncing with sm4svn part 1.

7534867: fix SSM crashes when selecting a song with only one player enabled
cddaab5: simplify SongUtil::GetStepsTypeAndDifficultyFromSortOrder
615aab0: add Style::GetUsesCenteredArrows (doubles + routine)
17f38e7: sanity check
[all code changes by Glenn Maynard]

src/ScreenGameplay.cpp

@@ -362,7 +362,17 @@ void ScreenGameplay::Init()
 	ScreenWithMenuElements::Init();
 
 	this->FillPlayerInfo( m_vPlayerInfo );
-	ASSERT_M( !m_vPlayerInfo.empty(), "m_vPlayerInfo must be filled by FillPlayerInfo" );
+
+	{
+		ASSERT_M( !m_vPlayerInfo.empty(), "m_vPlayerInfo must be filled by FillPlayerInfo" );
+
+		int iNumEnabledPlayers = 0;
+		FOREACH_EnabledPlayerInfo( m_vPlayerInfo, pi )
+			++iNumEnabledPlayers;
+
+		/* If this is 0, we have no active players and havn't been initialized correctly. */
+		ASSERT( iNumEnabledPlayers > 0 );
+	}
 
 	/* Pause MEMCARDMAN.  If a memory card is removed, we don't want to interrupt the
 	 * player by making a noise until the game finishes. */

src/ScreenSelectMusic.cpp

@@ -1003,7 +1003,7 @@ void ScreenSelectMusic::MenuStart( const InputEventPlus &input )
 			bool bSelectedRoutineSteps[NUM_PLAYERS], bAnySelectedRoutine = false;
 			bool bSelectedSameSteps = GAMESTATE->m_pCurSteps[PLAYER_1] == GAMESTATE->m_pCurSteps[PLAYER_2];
 
-			FOREACH_PlayerNumber( p )
+			FOREACH_HumanPlayer( p )
 			{
 				const Steps *pSteps = GAMESTATE->m_pCurSteps[p];
 				const StepsTypeInfo &sti = GAMEMAN->GetStepsTypeInfo( pSteps->m_StepsType );

src/SongUtil.cpp

@@ -917,18 +917,17 @@ bool SongUtil::GetStepsTypeAndDifficultyFromSortOrder( SortOrder so, StepsType &
 {
 	switch( so )
 	{
+	case SORT_BEGINNER_METER:			dcOut = Difficulty_Beginner;	break;
+	case SORT_EASY_METER:				dcOut = Difficulty_Easy;		break;
+	case SORT_MEDIUM_METER:			dcOut = Difficulty_Medium;		break;
+	case SORT_HARD_METER:				dcOut = Difficulty_Hard;		break;
+	case SORT_CHALLENGE_METER:			dcOut = Difficulty_Challenge;	break;
+	case SORT_DOUBLE_EASY_METER:		dcOut = Difficulty_Easy;		break;
+	case SORT_DOUBLE_MEDIUM_METER:		dcOut = Difficulty_Medium;		break;
+	case SORT_DOUBLE_HARD_METER:		dcOut = Difficulty_Hard;		break;
+	case SORT_DOUBLE_CHALLENGE_METER:	dcOut = Difficulty_Challenge;	break;
 	default:
 		return false;
-	case SORT_BEGINNER_METER:
-	case SORT_EASY_METER:
-	case SORT_MEDIUM_METER:
-	case SORT_HARD_METER:
-	case SORT_CHALLENGE_METER:
-	case SORT_DOUBLE_EASY_METER:
-	case SORT_DOUBLE_MEDIUM_METER:
-	case SORT_DOUBLE_HARD_METER:
-	case SORT_DOUBLE_CHALLENGE_METER:
-		break;	// fall through
 	}
 
 	switch( so )
@@ -963,20 +962,6 @@ bool SongUtil::GetStepsTypeAndDifficultyFromSortOrder( SortOrder so, StepsType &
 		break;
 	}
 
-	switch( so )
-	{
-	DEFAULT_FAIL( so );
-	case SORT_BEGINNER_METER:			dcOut = Difficulty_Beginner;	break;
-	case SORT_EASY_METER:				dcOut = Difficulty_Easy;		break;
-	case SORT_MEDIUM_METER:			dcOut = Difficulty_Medium;		break;
-	case SORT_HARD_METER:				dcOut = Difficulty_Hard;		break;
-	case SORT_CHALLENGE_METER:			dcOut = Difficulty_Challenge;	break;
-	case SORT_DOUBLE_EASY_METER:		dcOut = Difficulty_Easy;		break;
-	case SORT_DOUBLE_MEDIUM_METER:		dcOut = Difficulty_Medium;		break;
-	case SORT_DOUBLE_HARD_METER:		dcOut = Difficulty_Hard;		break;
-	case SORT_DOUBLE_CHALLENGE_METER:	dcOut = Difficulty_Challenge;	break;
-	}
-
 	return true;
 }
 

src/Style.cpp

@@ -20,6 +20,17 @@
 #include "NoteData.h"
 #include <float.h>
 
+bool Style::GetUsesCenteredArrows() const
+{
+	switch( m_StyleType )
+	{
+	case StyleType_OnePlayerTwoSides:
+	case StyleType_TwoPlayersSharedSides:
+		return true;
+	default:
+		return false;
+	}
+}
 
 void Style::GetTransformedNoteDataForStyle( PlayerNumber pn, const NoteData& original, NoteData& noteDataOut ) const
 {

src/Style.h

@@ -57,8 +57,8 @@ public:
 	int GameInputToColumn( const GameInput &GameI ) const;
 	RString ColToButtonName( int iCol ) const;
 
+	bool GetUsesCenteredArrows() const;
 	void GetTransformedNoteDataForStyle( PlayerNumber pn, const NoteData& original, NoteData& noteDataOut ) const;
-
 	void GetMinAndMaxColX( PlayerNumber pn, float& fMixXOut, float& fMaxXOut ) const;
 
 	// Lua