[Soft-Float] - Fixes a VU underflow flag edge case and apply some code recommandations.

In some cases, a Zero value could have it's underflow flag skipped, this is fixed.

We also start to simplify the code a bit per recommandations done in the pull request.

Author: GitHubProUser67

pcsx2/FPU.cpp

@@ -338,33 +338,27 @@ void CTC1() {
 }
 
 void CVT_S() {
-	if (CHECK_FPU_SOFT_ADDSUB || CHECK_FPU_SOFT_MUL || CHECK_FPU_SOFT_DIVSQRT) { _FdValUl_ = PS2Float::Itof(0, _FsValSl_).raw; }
-	else
-	{
-		_FdValf_ = (float)_FsValSl_;
-		_FdValf_ = fpuDouble(_FdValUl_);
-	}
+	_FdValf_ = (float)_FsValSl_;
+	_FdValf_ = fpuDouble(_FdValUl_);
 }
 
 void CVT_W() {
-	if (CHECK_FPU_SOFT_ADDSUB || CHECK_FPU_SOFT_MUL || CHECK_FPU_SOFT_DIVSQRT) { _FdValSl_ = PS2Float::Ftoi(0, _FsValUl_); }
-	else if ( ( _FsValUl_ & 0x7F800000 ) <= 0x4E800000 ) { _FdValSl_ = (s32)_FsValf_; }
+	if ( ( _FsValUl_ & 0x7F800000 ) <= 0x4E800000 ) { _FdValSl_ = (s32)_FsValf_; }
 	else if ( ( _FsValUl_ & 0x80000000 ) == 0 ) { _FdValUl_ = 0x7fffffff; }
 	else { _FdValUl_ = 0x80000000; }
 }
 
 void DIV_S() {
-	if (CHECK_FPU_SOFT_DIVSQRT)
+	if (checkDivideByZero( _FdValUl_, _FtValUl_, _FsValUl_, FPUflagD | FPUflagSD, FPUflagI | FPUflagSI)) return;
+	else if (CHECK_FPU_SOFT_DIVSQRT)
 	{
 		PS2Float divres = fpuAccurateDiv(_FsValUl_, _FtValUl_);
 		_FdValUl_ = divres.raw;
-		if (checkDivideByZeroInvalidSoft(divres, FPUflagD | FPUflagSD, FPUflagI | FPUflagSI)) return;
 		if (checkOverflowUnderflowSoft(divres, FPUflagO | FPUflagSO, true)) return;
 		checkOverflowUnderflowSoft(divres, FPUflagU | FPUflagSU, false);
 	}
 	else
 	{
-		if (checkDivideByZero( _FdValUl_, _FtValUl_, _FsValUl_, FPUflagD | FPUflagSD, FPUflagI | FPUflagSI)) return;
 		_FdValf_ = fpuDouble( _FsValUl_ ) / fpuDouble( _FtValUl_ );
 		if (checkOverflow( _FdValUl_, 0)) return;
 		checkUnderflow( _FdValUl_, 0);

pcsx2/PS2Float.cpp

@@ -666,85 +666,6 @@ PS2Float PS2Float::DoMul(PS2Float other)
 	return PS2Float(sign | (u32)(resExponent << MANTISSA_BITS) | (resMantissa & 0x7FFFFF));
 }
 
-PS2Float PS2Float::Itof(s32 complement, s32 f1)
-{
-	if (f1 == 0)
-		return PS2Float(0);
-
-	s32 resExponent;
-
-	bool negative = f1 < 0;
-
-	if (f1 == -2147483648)
-	{
-		if (complement <= 0)
-			// special case
-			return PS2Float(0xcf000000);
-		else
-			f1 = 2147483647;
-	}
-
-	s32 u = std::abs(f1);
-
-	s32 shifts;
-
-	s32 lzcnt = Common::CountLeadingSignBits(u);
-	if (lzcnt < 8)
-	{
-		s32 count = 8 - lzcnt;
-		u >>= count;
-		shifts = -count;
-	}
-	else
-	{
-		s32 count = lzcnt - 8;
-		u <<= count;
-		shifts = count;
-	}
-
-	resExponent = BIAS + MANTISSA_BITS - shifts - complement;
-
-	if (resExponent >= 158)
-		return negative ? PS2Float(0xcf000000) : PS2Float(0x4f000000);
-	else if (resExponent >= 0)
-		return PS2Float(negative, (u8)resExponent, (u32)u);
-
-	return PS2Float(0);
-}
-
-s32 PS2Float::Ftoi(s32 complement, u32 f1)
-{
-	u32 a, result;
-
-	a = f1;
-	if ((f1 & 0x7F800000) == 0)
-		result = 0;
-	else
-	{
-		complement = (s32)(f1 >> MANTISSA_BITS & 0xFF) + complement;
-		f1 &= 0x7FFFFF;
-		f1 |= 0x800000;
-		if (complement < 158)
-		{
-			if (complement > 126)
-			{
-				f1 = (f1 << 7) >> (31 - ((u8)complement - 126));
-				if ((s32)a < 0)
-					f1 = ~f1 + 1;
-				result = f1;
-			}
-			else
-				result = 0;
-		}
-		else if ((s32)a < 0)
-			result = SIGNMASK;
-		else
-			result = MAX_FLOATING_POINT_VALUE;
-	}
-
-	return (s32)result;
-}
-
 u8 PS2Float::Clip(u32 f1, u32 f2, bool& cplus, bool& cminus)
 {
 	bool resultPlus = false;

pcsx2/PS2Float.h

@@ -25,25 +25,21 @@ class PS2Float
 	constexpr u8 Exponent() const { return (raw >> 23) & 0xFF; }
 	constexpr bool Sign() const { return ((raw >> 31) & 1) != 0; }
 
-	PS2Float(s32 value);
+	__fi PS2Float(s32 value);
 
-	PS2Float(u32 value);
+	__fi PS2Float(u32 value);
 
-	PS2Float(float value);
+	__fi PS2Float(float value);
 
-	PS2Float(bool sign, u8 exponent, u32 mantissa);
+	__fi PS2Float(bool sign, u8 exponent, u32 mantissa);
 
-	static PS2Float Max();
+	__fi static PS2Float Max();
 
-	static PS2Float Min();
+	__fi static PS2Float Min();
 
-	static PS2Float One();
+	__fi static PS2Float One();
 
-	static PS2Float MinOne();
-
-	static PS2Float Itof(s32 complement, s32 f1);
-
-	static s32 Ftoi(s32 complement, u32 f1);
+	__fi static PS2Float MinOne();
 
 	static u8 Clip(u32 f1, u32 f2, bool& cplus, bool& cminus);
 

pcsx2/VUflags.cpp

@@ -49,21 +49,28 @@ static __ri u32 VU_MAC_UPDATE( s32 shift, VURegs* VU, float f)
 
 static __ri u32 VU_MAC_UPDATE(s32 shift, VURegs* VU, PS2Float f)
 {
+	bool isUnderflow = false;
+	
 	u32 v = f.raw;
 
 	if (v & PS2Float::SIGNMASK)
 		VU->macflag |= 0x0010 << shift;
 	else
 		VU->macflag &= ~(0x0010 << shift);
+	
+	if (f.uf)
+	{
+		isUnderflow = true;
+		VU->macflag = (VU->macflag & ~(0x1000 << shift)) | (0x0101 << shift);
+	}
 
 	if (f.IsZero())
 	{
 		VU->macflag = (VU->macflag & ~(0x1100 << shift)) | (0x0001 << shift);
 		return v;
 	}
-	else if (f.uf) { VU->macflag = (VU->macflag & ~(0x1000 << shift)) | (0x0101 << shift); }
 	else if (f.of) { VU->macflag = (VU->macflag & ~(0x0101 << shift)) | (0x1000 << shift); }
-	else { VU->macflag = (VU->macflag & ~(0x1101 << shift)); }
+	else if (!isUnderflow) { VU->macflag = (VU->macflag & ~(0x1101 << shift)); }
 
 	return v;
 }