122 lines
3.5 KiB
C++
122 lines
3.5 KiB
C++
/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
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/*
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* This file is part of the LibreOffice project.
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*
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/.
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*
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* This file incorporates work covered by the following license notice:
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*
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* Licensed to the Apache Software Foundation (ASF) under one or more
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* contributor license agreements. See the NOTICE file distributed
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* with this work for additional information regarding copyright
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* ownership. The ASF licenses this file to you under the Apache
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* License, Version 2.0 (the "License"); you may not use this file
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* except in compliance with the License. You may obtain a copy of
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* the License at http://www.apache.org/licenses/LICENSE-2.0 .
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*/
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#include <mcvmath.hxx>
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// ---------------------------------------------------------------------
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// die folgenden Tabellen enthalten sin(phi) * 2**14
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// fuer phi= 360Grad*2**-32 bis 360 Grad
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// def. fuer x: phi=360Grad * 2**(x-16)
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// d.h. x = 16 -> 360 Grad
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// x = -16 -> (2**-16) * 360 Grad
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// x: -16 ... 0 ... 15
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//x= 0, 1, 2, 3, 4, 5, 6, 7,
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// 8, 9, 10, 11, 12, 13, 14, 15
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static const short CosTab[16] =
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{
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16384, 16384, 16384, 16384, 16384, 16384, 16384, 16383,
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16379, 16364, 16305, 16069, 15137, 11585, 0, -16383
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};
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static const short SinTab[16]=
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{
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2, 3, 6, 13, 25, 50, 101, 201,
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402, 804, 1606, 3196, 6270, 11585, 16384, 0
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};
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/**************************************************************************
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|*
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|* ImpMultBig2()
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|*
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|* Beschreibung Multiplikation fuer FixPoint-Berechnungen
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|*
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**************************************************************************/
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// first parameter should be the bigger one
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Fix ImpMultBig2( const Fix& a, const Fix& b )
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{
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Fix f;
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f.x = (((b.x+FIX_A2)>>FIX_P2)*a.x+FIX_A3)>>FIX_P3;
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return f;
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}
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/**************************************************************************
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|*
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|* ImpSqrt()
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|*
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|* Beschreibung Wurzelfunktion fuer FixPoint-Berechnungen
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|*
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**************************************************************************/
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sal_uInt16 ImpSqrt( sal_uLong nRadi )
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{
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sal_uLong inf = 1;
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sal_uLong sup = nRadi;
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sal_uLong sqr;
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if ( !nRadi )
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return 0;
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while ( (inf<<1) <= sup )
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{
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sup >>= 1;
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inf <<= 1;
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}
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sqr = (sup+inf) >> 1; // Anfangswert der Iteration
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sqr = (nRadi/sqr + sqr) >> 1; // 2 Newton-Iterationen reichen fuer
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sqr = (nRadi/sqr + sqr) >> 1; // +- 1 Digit
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return sal::static_int_cast< sal_uInt16 >(sqr);
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}
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/**************************************************************************
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|*
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|* ImpExPI()
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|*
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|* Beschreibung EXPI-Funktion fuer FixPoint-Berechnungen
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|*
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**************************************************************************/
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// e**(i*nPhi), Einheit nPhi: 2**16 == 360 Grad
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FixCpx ImpExPI( sal_uInt16 nPhi )
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{
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short i;
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FixCpx aIter(1L); // e**(0*i)
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FixCpx Mul;
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const char Sft=14-FIX_POST;
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for ( i = 15; i >= 0; i-- )
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{
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if ( (1L<<i) & nPhi )
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{
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Mul.r.x = CosTab[i]>>Sft; // e**(i(phi1+phi2)) =
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Mul.i.x = SinTab[i]>>Sft; // e**(i*phi1)) * e**(i*phi2))
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aIter *= Mul;
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}
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}
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return aIter;
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}
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/* vim:set shiftwidth=4 softtabstop=4 expandtab: */
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