kernel/eka/euser/maths/um_utl.cpp
author Mike Kinghan <mikek@symbian.org>
Tue, 16 Nov 2010 14:39:21 +0000
branchGCC_SURGE
changeset 303 9b85206a602c
parent 0 a41df078684a
permissions -rw-r--r--
We need a way to pass flags to rombuilds in Raptor via extension flm interfaces, so that the CPP pass of the rom input files can be informed what toolchain we are building with and conditionally include or exclude files depending on whether the toolchain could build them.

// 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 "Eclipse Public License v1.0"
// which accompanies this distribution, and is available
// at the URL "http://www.eclipse.org/legal/epl-v10.html".
//
// Initial Contributors:
// Nokia Corporation - initial contribution.
//
// Contributors:
//
// Description:
// e32\euser\maths\um_utl.cpp
// 
//

#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

GLDEF_C void Panic(TMathPanic aPanic)
//
// Panic the process with USER-Math as the category.
//
	{

	User::Panic(_L("USER-Math"),aPanic);
	}



#ifdef __USE_VFP_MATH
extern "C" void __set_errno(TInt errno)
	{
	// Do nothing, we don't have an errno to set as we use
	// return values instead - return values are recosntructed
	// from the results/inputs, not from this
	}

extern "C" IMPORT_C TReal __ARM_scalbn(TReal,TInt);
extern "C" TReal scalbn(TReal x,TInt n)
	{
	return __ARM_scalbn(x,n);
	}
#endif



#ifndef __REALS_MACHINE_CODED__
EXPORT_C TReal Math::Poly(TReal aX,const SPoly *aPoly)
/**
Evaluates the polynomial:
{a[n]X^n + a[n-1]X^(n-1) + ... + a[2]X^2 + a[1]X^1 + a[0]}.


@param aX    The value of the x-variable 
@param aPoly A pointer to the structure containing the set of coefficients
             in the order: a[0], a[1], ..., a[n-1], a[n].

@return The result of the evaluation.
*/
//
// Evaluate a power series in x for a P_POLY coefficient table.
// Changed to use TRealX throughout the calculation
//
	{

	const TReal *pR=(&aPoly->c[aPoly->num-1]);
	TRealX r(*pR);
	TRealX x(aX);
	while (pR>&aPoly->c[0])
		{
		r*=x;
		r+=*--pR;
		}
	return(TReal(r));
	}




EXPORT_C void Math::PolyX(TRealX& aY, const TRealX& aX, TInt aDegree, const TRealX *aCoeff)
/**
Evaluates the polynomial:
{a[n]X^n + a[n-1]X^(n-1) + ... + a[2]X^2 + a[1]X^1 + a[0]}.

@param aY      A reference containing the result. 
@param aX      The value of the x-variable. 
@param aDegree The degree of the polynomial (the highest power of x
               which is present).
@param aCoeff  A pointer to a contiguous set of TRealX values containing
               the coefficients.
               They must be in the order: a[0], a[1], ..., a[n-1], a[n].
*/
	{
    // Evaluate a polynomial with TRealX argument and TRealX coefficients.
    // Return a TRealX result.

	const TRealX *pC=aCoeff+aDegree;
	aY=*pC;
	while(aDegree--)
		{
		aY*=aX;
		aY+=*--pC;
		}
	}
#endif