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1 769 jeremybenn 
/* Fixed.java -- Utility methods for fixed point arithmetics
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   Copyright (C) 2006 Free Software Foundation, Inc.
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This file is part of GNU Classpath.
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GNU Classpath is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2, or (at your option)
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any later version.
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GNU Classpath is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
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General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with GNU Classpath; see the file COPYING.  If not, write to the
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Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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02110-1301 USA.
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Linking this library statically or dynamically with other modules is
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making a combined work based on this library.  Thus, the terms and
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conditions of the GNU General Public License cover the whole
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combination.
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As a special exception, the copyright holders of this library give you
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permission to link this library with independent modules to produce an
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executable, regardless of the license terms of these independent
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modules, and to copy and distribute the resulting executable under
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terms of your choice, provided that you also meet, for each linked
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independent module, the terms and conditions of the license of that
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module.  An independent module is a module which is not derived from
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or based on this library.  If you modify this library, you may extend
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this exception to your version of the library, but you are not
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obligated to do so.  If you do not wish to do so, delete this
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exception statement from your version. */
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package gnu.java.math;
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/**
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 * Utility methods for fixed point arithmetics.
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 */
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public final class Fixed
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{
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  /**
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   * Private constructor to avoid instantiation.
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   */
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  private Fixed()
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  {
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    // Forbidden constructor.
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  }
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  /**
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   * Divides two fixed point values with <code>n</code> digits.
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   *
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   * @param n the number of digits
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   * @param a the first operand as fixed point value
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   * @param b the second operand as fixed point value
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   *
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   * @return <code>a / b</code> as fixed point value
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   */
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  public static int div(int n, int a, int b)
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  {
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    return (int) ((((long) a) << n) / b);
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  }
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  /**
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   * Multiplies two fixed point values with <code>n</code> digits.
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   *
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   * @param n the number of digits
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   * @param a the first operand as fixed point value
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   * @param b the second operand as fixed point value
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   *
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   * @return <code>a * b</code> as fixed point value
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   */
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  public static int mul(int n, int a, int b)
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  {
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    return (int) ((((long) a) * b) >> n);
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  }
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  /**
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   * Returns the ceiling value of a fixed point value <code>a</code> with
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   * the <code>n</code> digits.
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   *
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   * @param n the number of digits
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   * @param a the fixed point value
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   *
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   * @return <code>ceil(a)</code> as fixed point value
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   */
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  public static int ceil(int n, int a)
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  {
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    return (a + (1 << n - 1)) & -(1 << n);
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  }
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  /**
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   * Returns the floor value of a fixed point value <code>a</code> with
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   * <code>n</code> digits.
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   *
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   * @param n the number of digits
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   * @param a the fixed point value
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   *
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   * @return <code>floor(a)</code> as fixed point value
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   */
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  public static int floor(int n, int a)
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  {
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    return a & -(1 << n);
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  }
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  /**
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   * Truncates the number so that only the digits after the point are left.
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   *
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   * @param n the number of digits
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   * @param a the fixed point value
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   *
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   * @return the truncated value
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   */
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  public static int trunc(int n, int a)
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  {
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    return a & (0xFFFFFFFF >>> 32 - n);
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  }
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  /**
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   * Returns the round value of a fixed point value <code>a</code> with
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   * the <code>n</code> digits.
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   *
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   * @param n the number of digits
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   * @param a the fixed point value
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   *
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   * @return <code>round(a)</code> as fixed point value
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   */
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  public static int round(int n, int a)
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  {
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    return (a + (1 << (n - 1))) & -(1 << n);
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  }
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  /**
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   * Returns the fixed point value <code>a</code> with <code>n</code> digits
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   * as float.
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   *
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   * @param n the number of digits
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   * @param a the fixed point value
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   *
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   * @return the float value of <code>a</code>
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   */
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  public static float floatValue(int n, int a)
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  {
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    return ((float) a) / (1 << n);
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  }
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  /**
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   * Returns the fixed point value <code>a</code> with <code>n</code> digits
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   * as double.
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   *
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   * @param n the number of digits
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   * @param a the fixed point value
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   *
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   * @return the double value of <code>a</code>
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   */
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  public static double doubleValue(int n, int a)
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  {
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    return ((double) a) / (1 << n);
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  }
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  /**
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   * Returns the fixed point value that corresponds to the specified float
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   * value <code>a</code> with <code>n</code> digits.
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   *
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   * @param n the number of digits
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   * @param a the float value
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   *
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   * @return the fixed point value
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   */
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  public static int fixedValue(int n, float a)
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  {
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    return (int) (a * (1 << n));
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  }
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  /**
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   * Returns the fixed point value that corresponds to the specified double
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   * value <code>a</code> with <code>n</code> digits.
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   *
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   * @param n the number of digits
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   * @param a the double value
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   *
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   * @return the fixed point value
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   */
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  public static int fixedValue(int n, double a)
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  {
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    return (int) (a * (1 << n));
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  }
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  /**
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   * Returns the integer value of the specified fixed point value
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   * <code>a</code>. This simply cuts of the digits (== floor(a)).
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   *
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   * @param n the number of digits
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   * @param a the fixed point value
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   *
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   * @return the integer value
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   */
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  public static int intValue(int n, int a)
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  {
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    return a >> n;
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  }
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  /**
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   * Returns a fixed point decimal as rounded integer value.
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   *
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   * @param n the number of digits
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   * @param a the fixed point number
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   *
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   * @return the fixed point decimal as rounded integer value
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   */
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  public static int roundIntValue(int n, int a)
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  {
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    return (a + (1 << (n - 1))) >> n;
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  }
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}

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