diff -r c55016431358 -r 0a7b44b10206 symport/e32/euser/maths/um_pow.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/symport/e32/euser/maths/um_pow.cpp	Thu Jun 25 15:59:54 2009 +0100
@@ -0,0 +1,374 @@
+// Copyright (c) 1995-2009 Nokia Corporation and/or its subsidiary(-ies).
+// All rights reserved.
+// This component and the accompanying materials are made available
+// under the terms of the License "Symbian Foundation License v1.0"
+// which accompanies this distribution, and is available
+// at the URL "http://www.symbianfoundation.org/legal/sfl-v10.html".
+//
+// Initial Contributors:
+// Nokia Corporation - initial contribution.
+//
+// Contributors:
+//
+// Description:
+// e32\euser\maths\um_pow.cpp
+// Raise to the power.
+// 
+//
+
+#include "um_std.h"
+
+#if defined(__USE_VFP_MATH) && !defined(__CPU_HAS_VFP)
+#error	__USE_VFP_MATH was defined but not __CPU_HAS_VFP - impossible combination, check variant.mmh 
+#endif
+
+
+#ifndef __USE_VFP_MATH
+
+LOCAL_D const TUint32 ArtanhCoeffs[] =
+	{
+	0x5C17F0BC,0xB8AA3B29,0x80010000,	// polynomial approximation to (4/ln2)artanh(x)
+	0xD01FDDD8,0xF6384EE1,0x7FFF0000,	// for |x| <= (sqr2-1)/(sqr2+1)
+	0x7D0DDC69,0x93BB6287,0x7FFF0000,
+	0x6564D4F5,0xD30BB153,0x7FFE0000,
+	0x1546C858,0xA4258A33,0x7FFE0000,
+	0xCCE50DA9,0x864D28DF,0x7FFE0000,
+	0x8E1A5DBB,0xE35271A0,0x7FFD0000,
+	0xF5A67D92,0xC3A36B08,0x7FFD0000,
+	0x62D53E02,0xC4A1FFAC,0x7FFD0000
+	};
+
+LOCAL_D const TUint32 TwoToxCoeffs[] =
+	{
+	0x00000000,0x80000000,0x7FFF0000,	// polynomial approximation to 2^(x/8) for
+	0xD1CF79AC,0xB17217F7,0x7FFB0000,	// 0<=x<=1
+	0x162CF72B,0xF5FDEFFC,0x7FF60000,
+	0x23EC0D04,0xE35846B8,0x7FF10000,
+	0xBDB408D7,0x9D955B7E,0x7FEC0000,
+	0xFDD8A678,0xAEC3FE73,0x7FE60000,
+	0xBD6E3950,0xA184E90A,0x7FE00000,
+	0xC1054DA3,0xFFB259D8,0x7FD90000,
+	0x70893DE4,0xB8BEDE2F,0x7FD30000
+	};
+
+LOCAL_D const TUint32 TwoToNover8[] =
+	{
+	0xEA8BD6E7,0x8B95C1E3,0x7FFF0000,	// 2^0.125
+	0x8DB8A96F,0x9837F051,0x7FFF0000,	// 2^0.250
+	0xB15138EA,0xA5FED6A9,0x7FFF0000,	// 2^0.375
+	0xF9DE6484,0xB504F333,0x7FFF0000,	// 2^0.500
+	0x5506DADD,0xC5672A11,0x7FFF0000,	// 2^0.625
+	0xD69D6AF4,0xD744FCCA,0x7FFF0000,	// 2^0.750
+	0xDD24392F,0xEAC0C6E7,0x7FFF0000	// 2^0.875
+	};
+
+LOCAL_D const TUint32 Sqr2data[] = {0xF9DE6484,0xB504F333,0x7FFF0000};		// sqr2
+LOCAL_D const TUint32 Sqr2Invdata[] = {0xF9DE6484,0xB504F333,0x7FFE0000};	// 1/sqr2
+LOCAL_D const TUint32 Onedata[] = {0x00000000,0x80000000,0x7FFF0000};		// 1.0
+
+LOCAL_C void Log2(TRealX& y, TRealX& x)
+	{
+	// Calculate log2(x) and write to y
+	// Result to 64-bit precision to allow accurate powers
+	// Algorithm:
+	//		log2(aSrc)=log2(2^e.m) e=exponent of aSrc, m=mantissa 1<=m<2
+	//		log2(aSrc)=e+log2(m)
+	//		If e=-1 (0.5<=aSrc<1), let x=aSrc else let x=mantissa(aSrc)
+	//		If x>Sqr2, replace x with x/Sqr2
+	//		If x<Sqr2/2, replace x with x*Sqr2
+	//		Replace x with (x-1)/(x+1)
+	//		Use polynomial to calculate artanh(x) for |x| <= (sqr2-1)/(sqr2+1)
+	//			( use identity ln(x) = 2artanh((x-1)/(x+1)) )
+
+	const TRealX& Sqr2=*(const TRealX*)Sqr2data;
+	const TRealX& Sqr2Inv=*(const TRealX*)Sqr2Invdata;
+	const TRealX& One=*(const TRealX*)Onedata;
+
+	TInt n=(x.iExp-0x7FFF)<<1;
+	x.iExp=0x7FFF;
+	if (n!=-2)
+		{
+		if (x>Sqr2)
+			{
+			x*=Sqr2Inv;
+			n++;
+			}
+		}
+	else 
+		{
+		n=0;
+		x.iExp=0x7FFE;
+		if (x<Sqr2Inv)
+			{
+			x*=Sqr2;
+			n--;
+			}
+		}
+	x=(x-One)/(x+One);	// ln(x)=2artanh((x-1)/(x+1))
+	Math::PolyX(y,x*x,8,(const TRealX*)ArtanhCoeffs);
+	y*=x;
+	y+=TRealX(n);
+	if (y.iExp>1)
+		y.iExp--;
+	else
+		y.iExp=0;
+	}
+
+LOCAL_C TInt TwoTox(TRealX& y, TRealX& x)
+	{
+	// Calculate 2^x and write result to y. Result to 64 bit precision.
+	// Algorithm:
+	//		2^x = 2^int(x).2^frac(x)
+	//		2^int(x) just adds int(x) to the final result exponent
+	//		Reduce frac(x) to the range [0,0.125] (modulo 0.125)
+	//		Use polynomial to calculate 2^x for 0<=x<=0.125
+	//		Multiply by 2^(n/8) for n=0,1,2,3,4,5,6,7 to give 2^frac(x)
+
+	if (x.iExp)
+		x.iExp+=3;
+	TInt n=(TInt)x;
+	if (n<16384 && n>-16384)
+		{
+		if (x.iSign&1)
+			n--;
+		x-=TRealX(n);
+		Math::PolyX(y,x,8,(const TRealX*)TwoToxCoeffs);
+		y.iExp=TUint16(TInt(y.iExp)+(n>>3));
+		n&=7;
+		if (n)
+			y*= (*(const TRealX*)(TwoToNover8+3*n-3));
+		return KErrNone;
+		}
+	else
+		{
+		if (n<0)
+			{
+			y.SetZero();
+			return KErrUnderflow;
+			}
+		else
+			{
+			y.SetInfinite(0);
+			return KErrOverflow;
+			}
+		}
+	}
+
+
+
+
+EXPORT_C TInt Math::Pow(TReal &aTrg,const TReal &aSrc,const TReal &aPower)
+/**
+Calculates the value of x raised to the power of y.
+
+The behaviour conforms to that specified for pow() in the
+ISO C Standard ISO/IEC 9899 (Annex F), although floating-point exceptions
+are not supported.
+
+@param aTrg   A reference containing the result.
+@param aSrc   The x argument of the function.
+@param aPower The y argument of the function.
+
+@return KErrNone if successful;
+		KErrOverflow if the result is +/- infinity;
+	   	KErrUnderflow if the result is too small to be represented;
+		KErrArgument if the result is not a number (NaN).
+*/
+//
+// Evaluates aSrc raised to the power aPower and places the result in aTrg.
+// For non-special values algorithm is aTrg=2^(aPower*log2(aSrc))
+//
+	{
+	TRealX x,p;
+
+	TInt ret2=p.Set(aPower);
+	// pow(x, +/-0) -> 1 for any x, even a NaN
+	if (p.IsZero())
+		{
+		aTrg=1.0;
+		return KErrNone;
+		}
+
+	TInt ret1=x.Set(aSrc);
+	if (ret1==KErrArgument || ret2==KErrArgument)
+		{
+		// pow(+1, y) -> 1 for any y, even a NaN
+		// XXX First test should not be necessary, but on WINS
+		//     aSrc == 1.0 is true when aSrc is NaN.
+		if (ret1 != KErrArgument && aSrc == 1.0)
+			{
+			aTrg=aSrc;
+			return KErrNone;
+			}
+		SetNaN(aTrg);
+		return KErrArgument;
+		}
+
+	// Infinite power
+	if (ret2==KErrOverflow)
+		{
+		// figure out which of these cases we have:
+		//
+		// pow(x, -INF) -> +INF for |x| < 1  } flag = 0
+		// pow(x, +INF) -> +INF for |x| > 1  }
+		// pow(x, -INF) -> +0 for |x| > 1      } flag = 1
+		// pow(x, +INF) -> +0 for |x| < 1      }
+		//
+		// flag = 2 => |x| == 1.0
+		//
+		TInt flag=2;
+		if (Abs(aSrc)>1.0)
+			flag=p.iSign&1;
+		if (Abs(aSrc)<1.0)
+			flag=1-(p.iSign&1);
+		if (flag==0)
+			{
+			SetInfinite(aTrg,0);
+			return KErrOverflow;
+			}
+		if (flag==1)
+			{
+			SetZero(aTrg,0);
+			return KErrNone;
+			}
+		if (Abs(aSrc)==1.0)
+			{
+			// pow(-1, +/-INF) -> 1
+			aTrg=1.0;
+			return KErrNone;
+			}
+		// This should never happen (i.e. aSrc is NaN, which
+		// should be taken care of above)
+		SetNaN(aTrg);
+		return KErrArgument;
+		}
+
+	// Negative Base raised to a power
+	TInt odd=1;
+	if (x.iSign & 1)
+		{
+		TReal pint;
+		Math::Int(pint,aPower);
+		if (aPower-pint) // Checks that if aSrc is less than zero, then aPower is integral
+			{
+			// pow(-INF, y) -> +0 for y < 0 and not an odd integer
+			// pow(-INF, y) -> +INF for y > 0 and not an odd integer
+			// Since we're here, aPower is not integral, so can't be odd, either
+			if (ret1 == KErrOverflow)
+				{
+				if (aPower < 0)
+					{
+					SetZero(aTrg);
+					return KErrNone;
+					}
+				else
+					{
+					SetInfinite(aTrg,0);
+					return KErrOverflow;
+					}
+				}
+			SetNaN(aTrg);
+			return KErrArgument;
+			}
+		TReal powerby2=aPower*0.5;
+		Math::Int(pint,powerby2);
+		if (powerby2-pint)
+			odd=(-1);
+		x.iSign=0;
+		}
+
+	// Zero or infinity raised to a power
+	if (x.IsZero() || ret1==KErrOverflow)
+		{
+		if (x.IsZero() && p.IsZero())
+			{
+			aTrg=1.0;
+			return KErrNone;
+			}
+		TInt sign=(odd==-1 ? 1 : 0);
+		if ((x.IsZero() && (p.iSign&1)==0) || (ret1==KErrOverflow && (p.iSign&1)))
+			{
+			SetZero(aTrg,sign);				
+			return KErrNone;
+			}
+		else
+			{
+			SetInfinite(aTrg,sign);
+			return KErrOverflow;
+			}
+		}
+
+	TRealX y;
+	Log2(y,x);
+	x=y*p;			// this cannot overflow or underflow
+	TInt r=TwoTox(y,x);
+	if (odd<0)
+		y.iSign=1;
+	TInt r2=y.GetTReal(aTrg);
+	return (r==KErrNone)?r2:r;
+	}
+
+#else // __USE_VFP_MATH
+
+// definitions come from RVCT math library
+extern "C" TReal pow(TReal,TReal);
+
+EXPORT_C TInt Math::Pow(TReal &aTrg,const TReal &aSrc,const TReal &aPower)
+	{
+	aTrg = pow(aSrc,aPower);
+	if (Math::IsZero(aTrg) && !Math::IsZero(aSrc) && !Math::IsInfinite(aSrc) && !Math::IsInfinite(aPower))
+		return KErrUnderflow;
+	if (Math::IsFinite(aTrg))
+		return KErrNone;
+	if (Math::IsZero(aPower))	// pow(x, +/-0) -> 1 for any x, even a NaN
+		{
+		aTrg = 1.0;
+		return KErrNone;
+		}
+	if (Math::IsInfinite(aTrg))
+		return KErrOverflow;
+	if (aSrc==1.0)				// pow(+1, y) -> 1 for any y, even a NaN
+		{
+		aTrg=aSrc;
+		return KErrNone;
+		}
+	if (Math::IsInfinite(aPower))
+		{
+		if (aSrc == -1.0)		// pow(-1, +/-INF) -> 1
+			{
+			aTrg = 1.0;
+			return KErrNone;
+			}
+		if (((Abs(aSrc) < 1) && (aPower < 0)) ||	// pow(x, -INF) -> +INF for |x| < 1
+		    ((Abs(aSrc) > 1) && (aPower > 0)))		// pow(x, +INF) -> +INF for |x| > 1
+			{
+			SetInfinite(aTrg,0);
+			return KErrOverflow;
+			}
+		}
+	// pow(-INF, y) -> +INF for y > 0 and not an odd integer
+	if (Math::IsInfinite(aSrc) && (aSrc < 0) && (aPower > 0))
+		{
+		TBool odd = EFalse;
+		TReal pint;
+		Math::Int(pint, aPower);
+		if (aPower == pint)
+			{
+			TReal halfPower = aPower * 0.5;
+			Math::Int(pint, halfPower);
+			if (halfPower != pint)
+				odd = ETrue;
+			}
+		if (odd == EFalse)
+			{
+			SetInfinite(aTrg,0);
+			return KErrOverflow;
+			}
+		}
+
+	// Otherwise...
+	SetNaN(aTrg);
+	return KErrArgument;
+	}
+
+#endif