/* s3.core.javalang.Double.java -- object wrapper for double primitive
   Copyright (C) 1998, 1999, 2000 Free Software Foundation, Inc.
This file was part of GNU Classpath. It has been modified to fit the
OVM framework for use in the core. It is not meant to be a replacement
for the corresponding java.lang type, but only as a compatible object
in the core of the VM.
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., 59 Temple Place, Suite 330, Boston, MA
02111-1307 USA.
As a special exception, if you link this library with other files to
produce an executable, this library does not by itself cause the
resulting executable to be covered by the GNU General Public License.
This exception does not however invalidate any other reasons why the
executable file might be covered by the GNU General Public License. */
package java.lang;
import ovm.core.services.memory.VM_Address;

/**
 * Instances of class <code>Double</code> represent primitive
 * <code>double</code> values.
 *
 * Additionally, this class provides various helper functions and variables
 * related to doubles.
 *
 * @author Paul Fisher
 * @since JDK 1.0
 */
public final class Double
{
    /**
     * The minimum positive value a <code>double</code> may represent
     * is 5e-324.
     */
    public static final double MIN_VALUE = 5e-324;
    
    /**
     * The maximum positive value a <code>double</code> may represent
     * is 1.7976931348623157e+308.
     */
    public static final double MAX_VALUE = 1.7976931348623157e+308;
    
    /**
     * The value of a double representation -1.0/0.0, negative infinity.
     */
    public static final double NEGATIVE_INFINITY = -1.0/0.0;
    
    /**
     * The value of a double representing 1.0/0.0, positive infinity.
     */
    public static final double POSITIVE_INFINITY = 1.0/0.0;
    
    /**
     * All IEEE 754 values of NaN have the same value in Java.
     */
    public static final double NaN = 0.0/0.0;

    
    private double value;
    
    /**
     * Create a <code>Double</code> from the primitive <code>double</code>
     * specified.
     *
     * @param value the <code>double</code> argument
     */ 
    public Double(double value) {
	this.value = value;
    }
    
    /**
     * Create a <code>Double</code> from the specified <code>String</code>.
     *
     * This method calls <code>Double.parseDouble()</code>.
     *
     * @exception NumberFormatException when the <code>String</code> cannot
     *            be parsed into a <code>Float</code>.
     * @exception NullPointerException when the argument is <code>null</code>.
     * @param s the <code>String</code> to convert
     * @see #parseDouble(java.lang.String)
     */
    public Double(String s) throws NumberFormatException, NullPointerException 
    {
	value = parseDouble(s);
    }

    
    /**
     * Convert the <code>double</code> value of this <code>Double</code>
     * to a <code>String</code>.  This method calls
     * <code>Double.toString(double)</code> to do its dirty work.
     *
     * @return the <code>String</code> representation of this <code>Double</code>.
     * @see #toString(double)
     */
    public String toString() 
    {
	return toString(value);
    }
    
    /**
     * If the <code>Object</code> is not <code>null</code>, is an
     * <code>instanceof</code> <code>Double</code>, and represents
     * the same primitive <code>double</code> value return 
     * <code>true</code>.  Otherwise <code>false</code> is returned.
     *
     * @param obj the object to compare to
     * @return whether the objects are semantically equal.
     */
    public boolean equals(Object obj) 
    {
	return (obj instanceof Double && ((Double)obj).value == value);
    }

    /**
     * The hashcode is the value of the expression: <br>
     * <br>
     * <code>(int)(v^(v>>>32))</code><br>
     * <br>
     * where v is defined by: <br>
     * <code>long v = Double.doubleToLongBits(this.longValue());</code><br>
     */
    public int hashCode() 
    {
	long v = doubleToLongBits(value);
	return (int)(v^(v>>>32));
    }
    
    /**
     * Return the value of this <code>Double</code> when cast to an 
     * <code>int</code>.
     */
    public int intValue() 
    {
	return (int)value;
    }

    /**
     * Return the value of this <code>Double</code> when cast to a
     * <code>long</code>.
     */    
    public long longValue() 
    {
	return (long)value;
    }
    
    /**
     * Return the value of this <code>Double</code> when cast to a
     * <code>float</code>.
     */
    public float floatValue() 
    {
	return (float)value;
    }

    /**
     * Return the primitive <code>double</code> value represented by this
     * <code>Double</code>.
     */    
    public double doubleValue() 
    {
	return value;
    }
    
    
    /**
     * Return the result of calling <code>new Double(java.lang.String)</code>.
     *
     * @param s the <code>String</code> to convert to a <code>Double</code>.
     * @return a new <code>Double</code> representing the <code>String</code>'s
     *         numeric value.
     *
     * @exception NullPointerException thrown if <code>String</code> is 
     * <code>null</code>.
     * @exception NumberFormatException thrown if <code>String</code> cannot
     * be parsed as a <code>double</code>.
     * @see #Double(java.lang.String)
     * @see #parseDouble(java.lang.String)
     */
    public static Double valueOf(String s)
	throws NumberFormatException, NullPointerException
    {
	return new Double(s);
    }

    /**
     * Return <code>true</code> if the value of this <code>Double</code>
     * is the same as <code>NaN</code>, otherwise return <code>false</code>.
     * @return whether this <code>Double</code> is <code>NaN</code>.
     */
    public boolean isNaN() 
    {
	return isNaN(value);
    }
    
    /**
     * Return <code>true</code> if the <code>double</code> has the same
     * value as <code>NaN</code>, otherwise return <code>false</code>.
     *
     * @param d the <code>double</code> to compare
     * @return whether the argument is <code>NaN</code>.
     */
    public static boolean isNaN(double d) 
    {
        // This works since NaN != NaN is the only reflexive inequality
        // comparison which returns true.
        return d != d;
    }

    /**
     * Return <code>true</code> if the value of this <code>Double</code>
     * is the same as <code>NEGATIVE_INFINITY</code> or 
     * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
     *
     * @return whether this <code>Double</code> is (-/+) infinity.
     */
    public boolean isInfinite() 
    {
	return isInfinite(value);
    }
    
    /**
     * Return <code>true</code> if the <code>double</code> has a value 
     * equal to either <code>NEGATIVE_INFINITY</code> or 
     * <code>POSITIVE_INFINITY</code>, otherwise return <code>false</code>.
     *
     * @param d the <code>double</code> to compare
     * @return whether the argument is (-/+) infinity.
     */
    public static boolean isInfinite(double d) 
    {
	return (d == POSITIVE_INFINITY || d == NEGATIVE_INFINITY);
    }

    /**
     * Returns 0 if the <code>double</code> value of the argument is 
     * equal to the value of this <code>Double</code>.  Returns a number
     * less than zero if the value of this <code>Double</code> is less 
     * than the <code>double</code> value of the argument, and returns a 
     * number greater than zero if the value of this <code>Double</code> 
     * is greater than the <code>double</code> value of the argument.
     * <br>
     * <code>Double.NaN</code> is greater than any number other than itself, 
     * even <code>Double.POSITIVE_INFINITY</code>.
     * <br>
     * <code>0.0d</code> is greater than <code>-0.0d</code>.
     *
     * @param o the Object to compare to.
     * @return  0 if the <code>Double</code>s are the same, &lt; 0 if this
     *          <code>Double</code> is less than the <code>Double</code> in
     *          in question, or &gt; 0 if it is greater.
     */
    public int compareTo(Double d)
    {
	double x = d.doubleValue();

	if (value == NaN)
	    return (x == NaN) ? 0 : 1;
	if ((value == 0.0d) && (x == -0.0d))
	    return 1;
	if ((value == -0.0d) && (x == 0.0d))
	    return -1;

	return ((value - x) > 0) ? 1 : -1;
    }
    
    /**
     * Compares the specified <code>Object</code> to this <code>Double</code>
     * if and only if the <code>Object</code> is an instanceof 
     * <code>Double</code>.
     *
     * @param o the Object to compare to.
     * @return  0 if the <code>Double</code>s are the same, &lt; 0 if this
     *          <code>Double</code> is less than the <code>Double</code> in
     *          in question, or &gt; 0 if it is greater.
     * @throws ClassCastException if the argument is not a <code>Double</code>
     */
    public int compareTo(Object o)
    {
	return compareTo((Double)o);
    }

    /**
     * Convert the <code>double</code> to a <code>String</code>.
     * <P>
     * 
     * Floating-point string representation is fairly complex: here is a
     * rundown of the possible values.  "<CODE>[-]</CODE>" indicates that a
     * negative sign will be printed if the value (or exponent) is negative.
     * "<CODE>&lt;number&gt;</CODE>" means a string of digits (0-9).
     * "<CODE>&lt;digit&gt;</CODE>" means a single digit (0-9).
     * <P>
     *
     * <TABLE BORDER=1>
     * <TR><TH>Value of Float</TH><TH>String Representation</TH></TR>
     * <TR>
     *     <TD>[+-] 0</TD>
     *     <TD>[<CODE>-</CODE>]<CODE>0.0</CODE></TD>
     * </TR>
     * <TR>
     *     <TD>Between [+-] 10<SUP>-3</SUP> and 10<SUP>7</SUP></TD>
     *     <TD><CODE>[-]number.number</CODE></TD>
     * </TR>
     * <TR>
     *     <TD>Other numeric value</TD>
     *     <TD><CODE>[-]&lt;digit&gt;.&lt;number&gt;E[-]&lt;number&gt;</CODE></TD>
     * </TR>
     * <TR>
     *     <TD>[+-] infinity</TD>
     *     <TD><CODE>[-]Infinity</CODE></TD>
     * </TR>
     * <TR>
     *     <TD>NaN</TD>
     *     <TD><CODE>NaN</CODE></TD>
     * </TR>
     * </TABLE>
     *
     * Yes, negative zero <EM>is</EM> a possible value.  Note that there is
     * <EM>always</EM> a <CODE>.</CODE> and at least one digit printed after
     * it: even if the number is 3, it will be printed as <CODE>3.0</CODE>.
     * After the ".", all digits will be printed except trailing zeros.  No
     * truncation or rounding is done by this function.
     *
     *
     * @XXX specify where we are not in accord with the spec.
     *
     * @param d the <code>double</code> to convert
     * @return the <code>String</code> representing the <code>double</code>.
     */
    public native static String toString(double d);

  /**
   * Convert the double to the IEEE 754 floating-point "double format" bit
   * layout. Bit 63 (the most significant) is the sign bit, bits 62-52
   * (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0
   * (masked by 0x000fffffffffffffL) are the mantissa. This function
   * collapses all versions of NaN to 0x7ff8000000000000L. The result of this
   * function can be used as the argument to
   * <code>Double.longBitsToDouble(long)</code> to obtain the original
   * <code>double</code> value.
   *
   * @param value the <code>double</code> to convert
   * @return the bits of the <code>double</code>
   * @see #longBitsToDouble(long)
   */
    public static long doubleToLongBits(double value) {
        if (Double.isNaN(value)) return 0x7ff8000000000000L;
        // do we need to check +/- infinity ?
        return doubleToRawLongBits(value);
    }

    /**
     * Convert the double to the IEEE 754 floating-point "double format" bit
     * layout. Bit 63 (the most significant) is the sign bit, bits 62-52
     * (masked by 0x7ff0000000000000L) represent the exponent, and bits 51-0
     * (masked by 0x000fffffffffffffL) are the mantissa. This function
     * leaves NaN alone, rather than collapsing to a canonical value. The
     * result of this function can be used as the argument to
     * <code>Double.longBitsToDouble(long)</code> to obtain the original
     * <code>double</code> value.
     *
     * @param value the <code>double</code> to convert
     * @return the bits of the <code>double</code>
     * @see #longBitsToDouble(long)
     */
    public static long doubleToRawLongBits(double value) 
        throws VM_Address.BCfiatret {
        return /* hosted only */ 0;
    }

    /**
     * Return the <code>double</code> represented by the long
     * bits specified.
     *
     * @param bits the long bits representing a <code>double</code>
     * @return the <code>double</code> represented by the bits.
     */
    public static double longBitsToDouble(long l) throws VM_Address.BCfiatret {
        return /* hosted only */ 0;
    }

    /**
     * Parse the specified <code>String</code> as a <code>double</code>.
     * <P>
     *
     * The number is really read as <em>n * 10<sup>exponent</sup></em>.  The
     * first number is <em>n</em>, and if there is an "<code>E</code>"
     * ("<code>e</code>" is also acceptable), then the integer after that is
     * the exponent.
     * <P>
     *
     * Here are the possible forms the number can take:
     * <BR>
     * <TABLE BORDER=1>
     *     <TR><TH>Form</TH><TH>Examples</TH></TR>
     *     <TR><TD><CODE>[+-]&lt;number&gt;[.]</CODE></TD><TD>345., -10, 12</TD></TR>
     *     <TR><TD><CODE>[+-]&lt;number&gt;.&lt;number&gt;</CODE></TD><TD>40.2, 80.00, -12.30</TD></TR>
     *     <TR><TD><CODE>[+-]&lt;number&gt;[.]E[+-]&lt;number&gt;</CODE></TD><TD>80E12, -12e+7, 4.E-123</TD></TR>
     *     <TR><TD><CODE>[+-]&lt;number&gt;.&lt;number&gt;E[+-]&lt;number&gt;</CODE></TD><TD>6.02e-22, -40.2E+6, 12.3e9</TD></TR>
     * </TABLE>
     *
     * "<code>[+-]</code>" means either a plus or minus sign may go there, or
     * neither, in which case + is assumed.
     * <BR>
     * "<code>[.]</code>" means a dot may be placed here, but is optional.
     * <BR>
     * "<code>&lt;number&gt;</code>" means a string of digits (0-9), basically
     * an integer.  "<code>&lt;number&gt;.&lt;number&gt;</code>" is basically
     * a real number, a floating-point value.
     * <P>
     *
     * Remember that a <code>double</code> has a limited range.  If the
     * number you specify is greater than <code>Double.MAX_VALUE</code> or less
     * than <code>-Double.MAX_VALUE</code>, it will be set at
     * <code>Double.POSITIVE_INFINITY</code> or
     * <code>Double.NEGATIVE_INFINITY</code>, respectively.
     * <P>
     *
     * Note also that <code>double</code> does not have perfect precision.  Many
     * numbers cannot be precisely represented.  The number you specify
     * will be rounded to the nearest representable value.  <code>Double.MIN_VALUE</code> is
     * the margin of error for <code>double</code> values.
     * <P>
     *
     * If an unexpected character is found in the <code>String</code>, a
     * <code>NumberFormatException</code> will be thrown.  Spaces are not
     * allowed, and will cause the same exception.
     *
     * @XXX specify where/how we are not in accord with the spec.
     *
     * @param str the <code>String</code> to convert
     * @return the value of the <code>String</code> as a <code>double</code>.
     * @exception NumberFormatException when the string cannot be parsed to a
     *            <code>double</code>.
     * @exception NullPointerException when the string is null.
     * @since JDK 1.2
     * @see #MIN_VALUE
     * @see #MAX_VALUE
     * @see #POSITIVE_INFINITY
     * @see #NEGATIVE_INFINITY
     */
    public native static double parseDouble(String str) 
    throws NumberFormatException, NullPointerException;
}
