Pull in changes from 5.1 for using the standard Mersenne twister rath…

…er than a custom version.

src/Background.cpp

@@ -538,7 +538,7 @@ void BackgroundImpl::LoadFromSong( const Song* pSong )
 
 		// Pick the same random items every time the song is played.
 		RandomGen rnd( GetHashForString(pSong->GetSongDir()) );
-		random_shuffle( vsNames.begin(), vsNames.end(), rnd );
+		std::shuffle( vsNames.begin(), vsNames.end(), rnd );
 		int iSize = min( (int)g_iNumBackgrounds, (int)vsNames.size() );
 		vsNames.resize( iSize );
 

src/Course.cpp

@@ -368,7 +368,7 @@ static void CourseSortSongs( SongSort sort, vector<Song*> &vpPossibleSongs, Rand
 	{
 	DEFAULT_FAIL(sort);
 	case SongSort_Randomize:
-		random_shuffle( vpPossibleSongs.begin(), vpPossibleSongs.end(), rnd );
+		std::shuffle( vpPossibleSongs.begin(), vpPossibleSongs.end(), rnd );
 		break;
 	case SongSort_MostPlays:
 		if( PROFILEMAN )
@@ -428,7 +428,7 @@ bool Course::GetTrailUnsorted( StepsType st, CourseDifficulty cd, Trail &trail )
 		* will change every time it's viewed, and the displayed order will have no
 		* bearing on what you'll actually play. */
 		tmp_entries = m_vEntries;
-		random_shuffle( tmp_entries.begin(), tmp_entries.end(), rnd );
+		std::shuffle( tmp_entries.begin(), tmp_entries.end(), rnd );
 	}
 
 	const vector<CourseEntry> &entries = m_bShuffle ? tmp_entries:m_vEntries;
@@ -586,10 +586,14 @@ bool Course::GetTrailUnsorted( StepsType st, CourseDifficulty cd, Trail &trail )
 					iMaxDist = max( min( iMaxDist, MAX_BOTTOM_RANGE - iHighMeter ), iMinDist );
 
 					int iAdd;
-					if( iMaxDist == iMinDist )
+					if ( iMaxDist == iMinDist )
+					{
 						iAdd = iMaxDist;
+					}
 					else
-						iAdd = rnd( iMaxDist - iMinDist ) + iMinDist;
+					{
+						iAdd = random_up_to(rnd, iMaxDist - iMinDist) + iMinDist;
+					}
 					iLowMeter += iAdd;
 					iHighMeter += iAdd;
 				}
@@ -789,10 +793,14 @@ void Course::GetTrailUnsortedEndless( const vector<CourseEntry> &entries, Trail
 				iMaxDist = max( min( iMaxDist, MAX_BOTTOM_RANGE - iHighMeter ), iMinDist );
 
 				int iAdd;
-				if( iMaxDist == iMinDist )
+				if ( iMaxDist == iMinDist )
+				{
 					iAdd = iMaxDist;
+				}
 				else
-					iAdd = rnd( iMaxDist - iMinDist ) + iMinDist;
+				{
+					iAdd = random_up_to(rnd, iMaxDist - iMinDist) + iMinDist;
+				}
 				iLowMeter += iAdd;
 				iHighMeter += iAdd;
 			}

src/CourseUtil.cpp

@@ -304,7 +304,7 @@ void CourseUtil::AutogenOniFromArtist( const RString &sArtistName, RString sArti
 	 * song set changes. */
 	{
 		RandomGen rng( GetHashForString( sArtistName ) + aSongs.size() );
-		random_shuffle( aSongs.begin(), aSongs.end(), rng );
+		std::shuffle( aSongs.begin(), aSongs.end(), rng );
 	}
 
 	// Only use up to four songs.

src/GameState.cpp

@@ -316,8 +316,8 @@ void GameState::Reset()
 
 	NOTESKIN->RefreshNoteSkinData( m_pCurGame );
 
-	m_iGameSeed = rand();
-	m_iStageSeed = rand();
+	m_iGameSeed = g_RandomNumberGenerator();
+	m_iStageSeed = g_RandomNumberGenerator();
 
 	m_AdjustTokensBySongCostForFinalStageCheck= true;
 
@@ -1242,7 +1242,7 @@ void GameState::ResetStageStatistics()
 
 	// Reset the round seed. Do this here and not in FinishStage so that players
 	// get new shuffle patterns if they Back out of gameplay and play again.
-	m_iStageSeed = rand();
+	m_iStageSeed = g_RandomNumberGenerator();
 }
 
 void GameState::UpdateSongPosition( float fPositionSeconds, const TimingData &timing, const RageTimer &timestamp )
@@ -2495,7 +2495,7 @@ Difficulty GameState::GetHardestStepsDifficulty() const
 
 void GameState::SetNewStageSeed()
 {
-	m_iStageSeed= rand();
+	m_iStageSeed = g_RandomNumberGenerator();
 }
 
 bool GameState::IsEventMode() const

src/MusicWheel.cpp

@@ -1348,7 +1348,7 @@ void MusicWheel::StartRandom()
 	{
 		// Shuffle and use the roulette wheel.
 		RandomGen rnd;
-		random_shuffle( getWheelItemsData(SORT_ROULETTE).begin(), getWheelItemsData(SORT_ROULETTE).end(), rnd );
+		std::shuffle( getWheelItemsData(SORT_ROULETTE).begin(), getWheelItemsData(SORT_ROULETTE).end(), rnd );
 		GAMESTATE->m_SortOrder.Set( SORT_ROULETTE );
 	}
 	else

src/NoteDataUtil.cpp

@@ -1489,19 +1489,19 @@ static void GetTrackMapping( StepsType st, NoteDataUtil::TrackMapping tt, int Nu
 				switch(st) {
 					case StepsType_beat_single5:
 					{
-						random_shuffle( &iTakeFromTrack[0], &iTakeFromTrack[5], rnd );
-						random_shuffle( &iTakeFromTrack[6], &iTakeFromTrack[11], rnd );
+						std::shuffle( &iTakeFromTrack[0], &iTakeFromTrack[5], rnd );
+						std::shuffle( &iTakeFromTrack[6], &iTakeFromTrack[11], rnd );
 						break;
 					}
 					case StepsType_beat_single7:
 					{
-						random_shuffle( &iTakeFromTrack[1], &iTakeFromTrack[8], rnd );
-						random_shuffle( &iTakeFromTrack[9], &iTakeFromTrack[16], rnd );
+						std::shuffle( &iTakeFromTrack[1], &iTakeFromTrack[8], rnd );
+						std::shuffle( &iTakeFromTrack[9], &iTakeFromTrack[16], rnd );
 						break;
 					}
 					default:
 					{
-						random_shuffle( &iTakeFromTrack[0], &iTakeFromTrack[NumTracks], rnd );
+						std::shuffle( &iTakeFromTrack[0], &iTakeFromTrack[NumTracks], rnd );
 						break;
 					}
 				}

src/NotesLoaderBMS.cpp

@@ -483,7 +483,7 @@ struct bmsCommandTree
 			while (randomStack.size() < currentNode->branchHeight + 1) // if we're on branch level N we need N+1 values.
 				randomStack.push_back(0);
 
-			randomStack[currentNode->branchHeight] = rand() % StringToInt(value) + 1;
+			randomStack[currentNode->branchHeight] = random_up_to(g_RandomNumberGenerator, StringToInt(value)) + 1;
 		}
 		else
 		{

src/Player.cpp

@@ -3368,7 +3368,6 @@ RString Player::ApplyRandomAttack()
 	if( GAMESTATE->m_RandomAttacks.size() < 1 )
 		return "";
 
-	//int iAttackToUse = rand() % GAMESTATE->m_RandomAttacks.size();
 	DateTime now = DateTime::GetNowDate();
 	int iSeed = now.tm_hour * now.tm_min * now.tm_sec * now.tm_mday;
 	RandomGen rnd( GAMESTATE->m_iStageSeed * iSeed );

src/RageUtil.cpp

@@ -24,87 +24,19 @@ void UnicodeUpperLower(wchar_t *, size_t, const unsigned char *);
 
 RandomGen g_RandomNumberGenerator;
 
-MersenneTwister::MersenneTwister( int iSeed ) : m_iNext(0)
-{
-	Reset( iSeed );
-}
-
-void MersenneTwister::Reset( int iSeed )
-{
-	if( iSeed == 0 )
-		iSeed = time(NULL);
-
-	m_Values[0] = iSeed;
-	m_iNext = 0;
-	for( int i = 1; i < 624; ++i )
-		m_Values[i] = ((69069 * m_Values[i-1]) + 1) & 0xFFFFFFFF;
-
-	GenerateValues();
-}
-
-void MersenneTwister::GenerateValues()
-{
-	static const unsigned mask[] = { 0, 0x9908B0DF };
-
-	for( int i = 0; i < 227; ++i )
-	{
-		int iVal = (m_Values[i] & 0x80000000) | (m_Values[i+1] & 0x7FFFFFFF);
-		int iNext = (i + 397);
-
-		m_Values[i] = m_Values[iNext];
-		m_Values[i] ^= (iVal >> 1);
-		m_Values[i] ^= mask[iVal&1];
-	}
-
-	for( int i = 227; i < 623; ++i )
-	{
-		int iVal = (m_Values[i] & 0x80000000) | (m_Values[i+1] & 0x7FFFFFFF);
-		int iNext = (i + 397) - 624;
-
-		m_Values[i] = m_Values[iNext];
-		m_Values[i] ^= (iVal >> 1);
-		m_Values[i] ^= mask[iVal&1];
-	}
-
-	int iVal = (m_Values[623] & 0x80000000) + (m_Values[0] & 0x7FFFFFFF);
-	int iNext = (623 + 397) - 624;
-	m_Values[623] = m_Values[iNext] ^ (iVal>>1);
-	m_Values[623] ^= mask[iVal&1];
-}
-
-int MersenneTwister::Temper( int iVal )
-{
-	iVal ^= (iVal >> 11);
-	iVal ^= (iVal << 7) & 0x9D2C5680;
-	iVal ^= (iVal << 15) & 0xEFC60000;
-	iVal ^= (iVal >> 18);
-	return iVal;
-}
-
-int MersenneTwister::operator()()
-{
-	if( m_iNext == 624 )
-	{
-		m_iNext = 0;
-		GenerateValues();
-	}
-
-	return Temper( m_Values[m_iNext++] );
-}
-
 /* Extend MersenneTwister into Lua space. This is intended to replace
  * math.randomseed and math.random, so we conform to their behavior. */
 
 namespace
 {
-	MersenneTwister g_LuaPRNG;
+	RandomGen g_LuaPRNG;
 
-	/* To map from [0..2^31-1] to [0..1), we divide by 2^31. */
-	const double DIVISOR = pow( double(2), double(31) );
+	/* To map from [0..2^32-1] to [0..1), we divide by 2^32. */
+	const double DIVISOR = 4294967296.0;
 
 	static int Seed( lua_State *L )
 	{
-		g_LuaPRNG.Reset( IArg(1) );
+		g_LuaPRNG.seed( IArg(1) );
 		return 0;
 	}
 
@@ -125,7 +57,7 @@ namespace
 			{
 				int upper = IArg(1);
 				luaL_argcheck( L, 1 <= upper, 1, "interval is empty" );
-				lua_pushnumber( L, g_LuaPRNG(upper) + 1 );
+				lua_pushnumber(L, random_up_to(g_LuaPRNG, upper) + 1);
 				return 1;
 			}
 			/* [l..u] */
@@ -134,7 +66,7 @@ namespace
 				int lower = IArg(1);
 				int upper = IArg(2);
 				luaL_argcheck( L, lower < upper, 2, "interval is empty" );
-				lua_pushnumber( L, (int(g_LuaPRNG()) % (upper-lower+1)) + lower );
+				lua_pushnumber(L, random_up_to(g_LuaPRNG, upper - lower + 1) + lower);
 				return 1;
 			}
 
@@ -156,6 +88,11 @@ namespace
 
 LUA_REGISTER_NAMESPACE( MersenneTwister );
 
+void seed_lua_prng()
+{
+	g_LuaPRNG.seed(static_cast<unsigned int>(time(nullptr)));
+}
+
 void fapproach( float& val, float other_val, float to_move )
 {
 	ASSERT_M( to_move >= 0, ssprintf("to_move: %f < 0", to_move) );

src/RageUtil.h

@@ -4,6 +4,7 @@
 #define RAGE_UTIL_H
 
 #include <map>
+#include <random>
 #include <vector>
 #include <sstream>
 class RageFileDriver;
@@ -238,35 +239,38 @@ inline uint32_t Swap24LE( uint32_t n ) { return Swap24( n ); }
 inline uint16_t Swap16LE( uint16_t n ) { return Swap16( n ); }
 #endif
 
-struct MersenneTwister
+typedef std::mt19937 RandomGen;
+
+extern RandomGen g_RandomNumberGenerator;
+
+void seed_lua_prng();
+
+inline int random_up_to(RandomGen& rng, int limit)
 {
-	MersenneTwister( int iSeed = 0 ); // 0 = time()
-	int operator()(); // returns [0,2^31-1]
-	int operator()( int n ) // returns [0,n)
+	RandomGen::result_type res = rng();
+	// Cutting off the incomplete [0,n) chunk at the max value makes the result
+	// more evenly distributed. -Kyz
+	RandomGen::result_type up_to_max = RandomGen::max() - (RandomGen::max() % limit);
+	while (res > up_to_max)
 	{
-		return (*this)() % n;
+		res = rng();
 	}
 
-	void Reset( int iSeed );
-
-private:
-	static int Temper( int iValue );
-	void GenerateValues();
-
-	int m_Values[624];
-	int m_iNext;
-};
-typedef MersenneTwister RandomGen;
+	return int(res % limit);
+}
 
-extern RandomGen g_RandomNumberGenerator;
+inline int random_up_to(int limit)
+{
+	return random_up_to(g_RandomNumberGenerator, limit);
+}
 
 /**
  * @brief Generate a random float between 0 inclusive and 1 exclusive.
  * @return the random float.
  */
 inline float RandomFloat()
 {
-	return g_RandomNumberGenerator() / 2147483648.0f;
+	return float(g_RandomNumberGenerator() / 4294967296.0);
 }
 
 /**
@@ -281,15 +285,15 @@ inline float RandomFloat( float fLow, float fHigh )
 }
 
 // Returns an integer between nLow and nHigh inclusive
-inline int RandomInt( int nLow, int nHigh )
+inline int RandomInt(int low, int high)
 {
-	return static_cast<int>( g_RandomNumberGenerator(nHigh - nLow + 1) + nLow );
+	return random_up_to(g_RandomNumberGenerator, high - low + 1) + low;
 }
 
 // Returns an integer between 0 and n-1 inclusive (replacement for rand() % n).
-inline int RandomInt( int n )
+inline int RandomInt(int n)
 {
-	return static_cast<int>( g_RandomNumberGenerator(n) );
+	return random_up_to(g_RandomNumberGenerator, n);
 }
 
 

src/RandomSample.cpp

@@ -56,7 +56,7 @@ bool RandomSample::LoadSoundDir( RString sDir, int iMaxToLoad )
 	GetDirListing( sDir + "*.ogg", arraySoundFiles );
 	GetDirListing( sDir + "*.wav", arraySoundFiles );
 
-	random_shuffle( arraySoundFiles.begin(), arraySoundFiles.end() );
+	std::shuffle( arraySoundFiles.begin(), arraySoundFiles.end(), g_RandomNumberGenerator );
 	arraySoundFiles.resize( min( arraySoundFiles.size(), (unsigned)iMaxToLoad ) );
 
 	for( unsigned i=0; i<arraySoundFiles.size(); i++ )

src/ScreenDebugOverlay.cpp

@@ -910,8 +910,10 @@ static void FillProfileStats( Profile *pProfile )
 		vector<Steps*> vpAllSteps = (*pSong)->GetAllSteps();
 		FOREACH( Steps*, vpAllSteps, pSteps )
 		{
-			if( rand() % 5 )
-				pProfile->IncrementStepsPlayCount( *pSong, *pSteps );
+			if (random_up_to(5))
+			{
+				pProfile->IncrementStepsPlayCount(*pSong, *pSteps);
+			}
 			for( int i=0; i<iCount; i++ )
 			{
 				int iIndex = 0;
@@ -928,8 +930,10 @@ static void FillProfileStats( Profile *pProfile )
 		(*pCourse)->GetAllTrails( vpAllTrails );
 		FOREACH( Trail*, vpAllTrails, pTrail )
 		{
-			if( rand() % 5 )
-				pProfile->IncrementCoursePlayCount( *pCourse, *pTrail );
+			if (random_up_to(5))
+			{
+				pProfile->IncrementCoursePlayCount(*pCourse, *pTrail);
+			}
 			for( int i=0; i<iCount; i++ )
 			{
 				int iIndex = 0;