| /* Fixed.java -- Utility methods for fixed point arithmetics |
| Copyright (C) 2006 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package gnu.java.math; |
| |
| /** |
| * Utility methods for fixed point arithmetics. |
| */ |
| public final class Fixed |
| { |
| |
| /** |
| * Private constructor to avoid instantiation. |
| */ |
| private Fixed() |
| { |
| // Forbidden constructor. |
| } |
| |
| /** |
| * Divides two fixed point values with <code>n</code> digits. |
| * |
| * @param n the number of digits |
| * @param a the first operand as fixed point value |
| * @param b the second operand as fixed point value |
| * |
| * @return <code>a / b</code> as fixed point value |
| */ |
| public static int div(int n, int a, int b) |
| { |
| return (int) ((((long) a) << n) / b); |
| } |
| |
| /** |
| * Multiplies two fixed point values with <code>n</code> digits. |
| * |
| * @param n the number of digits |
| * @param a the first operand as fixed point value |
| * @param b the second operand as fixed point value |
| * |
| * @return <code>a * b</code> as fixed point value |
| */ |
| public static int mul(int n, int a, int b) |
| { |
| return (int) ((((long) a) * b) >> n); |
| } |
| |
| /** |
| * Returns the ceiling value of a fixed point value <code>a</code> with |
| * the <code>n</code> digits. |
| * |
| * @param n the number of digits |
| * @param a the fixed point value |
| * |
| * @return <code>ceil(a)</code> as fixed point value |
| */ |
| public static int ceil(int n, int a) |
| { |
| return (a + (1 << n - 1)) & -(1 << n); |
| } |
| |
| /** |
| * Returns the floor value of a fixed point value <code>a</code> with |
| * <code>n</code> digits. |
| * |
| * @param n the number of digits |
| * @param a the fixed point value |
| * |
| * @return <code>floor(a)</code> as fixed point value |
| */ |
| public static int floor(int n, int a) |
| { |
| return a & -(1 << n); |
| } |
| |
| /** |
| * Truncates the number so that only the digits after the point are left. |
| * |
| * @param n the number of digits |
| * @param a the fixed point value |
| * |
| * @return the truncated value |
| */ |
| public static int trunc(int n, int a) |
| { |
| return a & (0xFFFFFFFF >>> 32 - n); |
| } |
| |
| /** |
| * Returns the round value of a fixed point value <code>a</code> with |
| * the <code>n</code> digits. |
| * |
| * @param n the number of digits |
| * @param a the fixed point value |
| * |
| * @return <code>round(a)</code> as fixed point value |
| */ |
| public static int round(int n, int a) |
| { |
| return (a + (1 << (n - 1))) & -(1 << n); |
| } |
| |
| /** |
| * Returns the fixed point value <code>a</code> with <code>n</code> digits |
| * as float. |
| * |
| * @param n the number of digits |
| * @param a the fixed point value |
| * |
| * @return the float value of <code>a</code> |
| */ |
| public static float floatValue(int n, int a) |
| { |
| return ((float) a) / (1 << n); |
| } |
| |
| /** |
| * Returns the fixed point value <code>a</code> with <code>n</code> digits |
| * as double. |
| * |
| * @param n the number of digits |
| * @param a the fixed point value |
| * |
| * @return the double value of <code>a</code> |
| */ |
| public static double doubleValue(int n, int a) |
| { |
| return ((double) a) / (1 << n); |
| } |
| |
| /** |
| * Returns the fixed point value that corresponds to the specified float |
| * value <code>a</code> with <code>n</code> digits. |
| * |
| * @param n the number of digits |
| * @param a the float value |
| * |
| * @return the fixed point value |
| */ |
| public static int fixedValue(int n, float a) |
| { |
| return (int) (a * (1 << n)); |
| } |
| |
| /** |
| * Returns the fixed point value that corresponds to the specified double |
| * value <code>a</code> with <code>n</code> digits. |
| * |
| * @param n the number of digits |
| * @param a the double value |
| * |
| * @return the fixed point value |
| */ |
| public static int fixedValue(int n, double a) |
| { |
| return (int) (a * (1 << n)); |
| } |
| |
| /** |
| * Returns the integer value of the specified fixed point value |
| * <code>a</code>. This simply cuts of the digits (== floor(a)). |
| * |
| * @param n the number of digits |
| * @param a the fixed point value |
| * |
| * @return the integer value |
| */ |
| public static int intValue(int n, int a) |
| { |
| return a >> n; |
| } |
| |
| /** |
| * Returns a fixed point decimal as rounded integer value. |
| * |
| * @param n the number of digits |
| * @param a the fixed point number |
| * |
| * @return the fixed point decimal as rounded integer value |
| */ |
| public static int roundIntValue(int n, int a) |
| { |
| return (a + (1 << (n - 1))) >> n; |
| } |
| } |