svtools/source/dialogs/mcvmath.cxx

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */
   2 /*
   3  * This file is part of the LibreOffice project.
   4  *
   5  * This Source Code Form is subject to the terms of the Mozilla Public
   6  * License, v. 2.0. If a copy of the MPL was not distributed with this
   7  * file, You can obtain one at http://mozilla.org/MPL/2.0/.
   8  *
   9  * This file incorporates work covered by the following license notice:
  10  *
  11  *   Licensed to the Apache Software Foundation (ASF) under one or more
  12  *   contributor license agreements. See the NOTICE file distributed
  13  *   with this work for additional information regarding copyright
  14  *   ownership. The ASF licenses this file to you under the Apache
  15  *   License, Version 2.0 (the "License"); you may not use this file
  16  *   except in compliance with the License. You may obtain a copy of
  17  *   the License at http://www.apache.org/licenses/LICENSE-2.0 .
  18  */
  19
  20
  21 #include "mcvmath.hxx"
  22
  23
  24 // die folgenden Tabellen enthalten     sin(phi) * 2**14
  25 // fuer phi= 360Grad*2**-32 bis 360 Grad
  26 // def. fuer x: phi=360Grad * 2**(x-16)
  27 //           d.h. x =  16 -> 360 Grad
  28 //                x = -16 -> (2**-16) * 360 Grad
  29 //         x:         -16 ... 0 ... 15
  30 //x=    0,     1,     2,     3,     4,     5,     6,      7,
  31 //      8,     9,    10,    11,    12,    13,    14,     15
  32
  33 static const short CosTab[16] =
  34 {
  35     16384, 16384, 16384, 16384, 16384, 16384, 16384,  16383,
  36     16379, 16364, 16305, 16069, 15137, 11585,     0, -16383
  37 };
  38 static const short SinTab[16]=
  39 {
  40         2,     3,      6,    13,    25,     50,   101,  201,
  41       402,   804,   1606,  3196,  6270,  11585, 16384,    0
  42 };
  43
  44 /**************************************************************************
  45 |*
  46 |*    ImpMultBig2()
  47 |*
  48 |*    Description       Multiplier for FixPoint-calculations
  49 |*
  50 **************************************************************************/
  51
  52 //  first parameter should be the larger one
  53
  54 Fix ImpMultBig2( const Fix& a, const Fix& b )
  55 {
  56     Fix f;
  57     f.x = (((b.x+FIX_A2)>>FIX_P2)*a.x+FIX_A3)>>FIX_P3;
  58     return f;
  59 }
  60
  61 /**************************************************************************
  62 |*
  63 |*    ImpSqrt()
  64 |*
  65 |*    Description       SquareRoot function for FixPoint-calculations
  66 |*
  67 **************************************************************************/
  68
  69 sal_uInt16 ImpSqrt( sal_uLong nRadi )
  70 {
  71     sal_uLong  inf = 1;
  72     sal_uLong  sup = nRadi;
  73     sal_uLong sqr;
  74
  75     if ( !nRadi )
  76         return 0;
  77
  78     while ( (inf<<1) <= sup )
  79     {
  80         sup >>= 1;
  81         inf <<= 1;
  82     }
  83     sqr = (sup+inf) >> 1;               // startvalue for iteration
  84
  85     sqr = (nRadi/sqr + sqr) >> 1;       // 2 Newton-Iterations suffice for
  86     sqr = (nRadi/sqr + sqr) >> 1;       // +- 1 Digit
  87
  88     return sal::static_int_cast< sal_uInt16 >(sqr);
  89 }
  90
  91 /**************************************************************************
  92 |*
  93 |*    ImpExPI()
  94 |*
  95 |*    Description       EXPI funktion or FixPoint-calculations
  96 |*
  97 **************************************************************************/
  98
  99 // e**(i*nPhi), unit nPhi: 2**16 == 360 degrees
 100
 101 FixCpx ImpExPI( sal_uInt16 nPhi )
 102 {
 103     short i;
 104     FixCpx aIter(1L);                   // e**(0*i)
 105     FixCpx Mul;
 106     const char Sft=14-FIX_POST;
 107
 108     for ( i = 15; i >= 0; i-- )
 109     {
 110         if ( (1L<<i) & nPhi )
 111         {
 112             Mul.r.x = CosTab[i]>>Sft;   // e**(i(phi1+phi2)) =
 113             Mul.i.x = SinTab[i]>>Sft;   // e**(i*phi1)) * e**(i*phi2))
 114             aIter  *= Mul;
 115         }
 116     }
 117
 118     return aIter;
 119 }
 120
 121 /* vim:set shiftwidth=4 softtabstop=4 expandtab: */