J. Duke | 319a3b9 | 2007-12-01 00:00:00 +0000 | [diff] [blame^] | 1 | /* |
| 2 | * Copyright 2007 Sun Microsystems, Inc. All Rights Reserved. |
| 3 | * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| 4 | * |
| 5 | * This code is free software; you can redistribute it and/or modify it |
| 6 | * under the terms of the GNU General Public License version 2 only, as |
| 7 | * published by the Free Software Foundation. Sun designates this |
| 8 | * particular file as subject to the "Classpath" exception as provided |
| 9 | * by Sun in the LICENSE file that accompanied this code. |
| 10 | * |
| 11 | * This code is distributed in the hope that it will be useful, but WITHOUT |
| 12 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 13 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License |
| 14 | * version 2 for more details (a copy is included in the LICENSE file that |
| 15 | * accompanied this code). |
| 16 | * |
| 17 | * You should have received a copy of the GNU General Public License version |
| 18 | * 2 along with this work; if not, write to the Free Software Foundation, |
| 19 | * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| 20 | * |
| 21 | * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara, |
| 22 | * CA 95054 USA or visit www.sun.com if you need additional information or |
| 23 | * have any questions. |
| 24 | */ |
| 25 | |
| 26 | package sun.java2d.pisces; |
| 27 | |
| 28 | public class PiscesMath { |
| 29 | |
| 30 | private PiscesMath() {} |
| 31 | |
| 32 | private static final int SINTAB_LG_ENTRIES = 10; |
| 33 | private static final int SINTAB_ENTRIES = 1 << SINTAB_LG_ENTRIES; |
| 34 | private static int[] sintab; |
| 35 | |
| 36 | public static final int PI = (int)(Math.PI*65536.0); |
| 37 | public static final int TWO_PI = (int)(2.0*Math.PI*65536.0); |
| 38 | public static final int PI_OVER_TWO = (int)((Math.PI/2.0)*65536.0); |
| 39 | public static final int SQRT_TWO = (int)(Math.sqrt(2.0)*65536.0); |
| 40 | |
| 41 | static { |
| 42 | sintab = new int[SINTAB_ENTRIES + 1]; |
| 43 | for (int i = 0; i < SINTAB_ENTRIES + 1; i++) { |
| 44 | double theta = i*(Math.PI/2.0)/SINTAB_ENTRIES; |
| 45 | sintab[i] = (int)(Math.sin(theta)*65536.0); |
| 46 | } |
| 47 | } |
| 48 | |
| 49 | public static int sin(int theta) { |
| 50 | int sign = 1; |
| 51 | if (theta < 0) { |
| 52 | theta = -theta; |
| 53 | sign = -1; |
| 54 | } |
| 55 | // 0 <= theta |
| 56 | while (theta >= TWO_PI) { |
| 57 | theta -= TWO_PI; |
| 58 | } |
| 59 | // 0 <= theta < 2*PI |
| 60 | if (theta >= PI) { |
| 61 | theta = TWO_PI - theta; |
| 62 | sign = -sign; |
| 63 | } |
| 64 | // 0 <= theta < PI |
| 65 | if (theta > PI_OVER_TWO) { |
| 66 | theta = PI - theta; |
| 67 | } |
| 68 | // 0 <= theta <= PI/2 |
| 69 | int itheta = (int)((long)theta*SINTAB_ENTRIES/(PI_OVER_TWO)); |
| 70 | return sign*sintab[itheta]; |
| 71 | } |
| 72 | |
| 73 | public static int cos(int theta) { |
| 74 | return sin(PI_OVER_TWO - theta); |
| 75 | } |
| 76 | |
| 77 | // public static double sqrt(double x) { |
| 78 | // double dsqrt = Math.sqrt(x); |
| 79 | // int ix = (int)(x*65536.0); |
| 80 | // Int Isqrt = Isqrt(Ix); |
| 81 | |
| 82 | // Long Lx = (Long)(X*65536.0); |
| 83 | // Long Lsqrt = Lsqrt(Lx); |
| 84 | |
| 85 | // System.Out.Println(); |
| 86 | // System.Out.Println("X = " + X); |
| 87 | // System.Out.Println("Dsqrt = " + Dsqrt); |
| 88 | |
| 89 | // System.Out.Println("Ix = " + Ix); |
| 90 | // System.Out.Println("Isqrt = " + Isqrt/65536.0); |
| 91 | |
| 92 | // System.Out.Println("Lx = " + Lx); |
| 93 | // System.Out.Println("Lsqrt = " + Lsqrt/65536.0); |
| 94 | |
| 95 | // Return Dsqrt; |
| 96 | // } |
| 97 | |
| 98 | // From Ken Turkowski, _Fixed-Point Square Root_, In Graphics Gems V |
| 99 | public static int isqrt(int x) { |
| 100 | int fracbits = 16; |
| 101 | |
| 102 | int root = 0; |
| 103 | int remHi = 0; |
| 104 | int remLo = x; |
| 105 | int count = 15 + fracbits/2; |
| 106 | |
| 107 | do { |
| 108 | remHi = (remHi << 2) | (remLo >>> 30); // N.B. - unsigned shift R |
| 109 | remLo <<= 2; |
| 110 | root <<= 1; |
| 111 | int testdiv = (root << 1) + 1; |
| 112 | if (remHi >= testdiv) { |
| 113 | remHi -= testdiv; |
| 114 | root++; |
| 115 | } |
| 116 | } while (count-- != 0); |
| 117 | |
| 118 | return root; |
| 119 | } |
| 120 | |
| 121 | public static long lsqrt(long x) { |
| 122 | int fracbits = 16; |
| 123 | |
| 124 | long root = 0; |
| 125 | long remHi = 0; |
| 126 | long remLo = x; |
| 127 | int count = 31 + fracbits/2; |
| 128 | |
| 129 | do { |
| 130 | remHi = (remHi << 2) | (remLo >>> 62); // N.B. - unsigned shift R |
| 131 | remLo <<= 2; |
| 132 | root <<= 1; |
| 133 | long testDiv = (root << 1) + 1; |
| 134 | if (remHi >= testDiv) { |
| 135 | remHi -= testDiv; |
| 136 | root++; |
| 137 | } |
| 138 | } while (count-- != 0); |
| 139 | |
| 140 | return root; |
| 141 | } |
| 142 | |
| 143 | public static double hypot(double x, double y) { |
| 144 | // new RuntimeException().printStackTrace(); |
| 145 | return Math.sqrt(x*x + y*y); |
| 146 | } |
| 147 | |
| 148 | public static int hypot(int x, int y) { |
| 149 | return (int)((lsqrt((long)x*x + (long)y*y) + 128) >> 8); |
| 150 | } |
| 151 | |
| 152 | public static long hypot(long x, long y) { |
| 153 | return (lsqrt(x*x + y*y) + 128) >> 8; |
| 154 | } |
| 155 | } |