/* s3.core.javalang.Float
   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>Float</code> represent primitive
 * <code>float</code> values.
 *
 * Additionally, this class provides various helper functions and variables
 * related to floats.
 *
 * @author Paul Fisher
 * @author Ben L. Titzer
 * @since JDK 1.0
 */
public final class Float
{
    /**
     * The minimum positive value a <code>float</code> may represent
     * is 1.4e-45.
     */
    public static final float MIN_VALUE = 1.4e-45f;

    /**
     * The maximum positive value a <code>double</code> may represent
     * is 3.4028235e+38f.
     */
    public static final float MAX_VALUE = 3.4028235e+38f;

    /**
     * The value of a float representation -1.0/0.0, negative infinity.
     */
    public static final float NEGATIVE_INFINITY = -1.0f/0.0f;

    /**
     * The value of a float representation 1.0/0.0, positive infinity.
     */
    public static final float POSITIVE_INFINITY = 1.0f/0.0f;

    /**
     * All IEEE 754 values of NaN have the same value in Java.
     */
    public static final float NaN = 0.0f/0.0f;

    private float value;

    /**
     * Create a <code>float</code> from the primitive <code>Float</code>
     * specified.
     *
     * @param value the <code>Float</code> argument
     */ 
    public Float(float value) 
    {
	this.value = value;
    }

    /**
     * Create a <code>Float</code> from the primitive <code>double</code>
     * specified.
     *
     * @param value the <code>double</code> argument
     */ 
    public Float(double value) 
    {
	this((float)value);
    }

    /**
     * Create a <code>Float</code> from the specified <code>String</code>.
     *
     * This method calls <code>Float.parseFloat()</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 #parseFloat(java.lang.String)
     */
    public Float(String s) throws NumberFormatException, NullPointerException
    {
	value = parseFloat(s);
    }
    
    /**
     * Convert the <code>float</code> value of this <code>Float</code>
     * to a <code>String</code>.  This method calls
     * <code>Float.toString(float)</code> to do its dirty work.
     *
     * @return the <code>String</code> representation of this <code>Float</code>.
     * @see #toString(float)
     */
    public String toString() {
	return toString(value);
    }
    
    /**
     * If the <code>Object</code> is not <code>null</code>, is an
     * <code>instanceof</code> <code>Float</code>, and represents
     * the same primitive <code>float</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 Float && ((Float)obj).value == value);
    }

    /**
     * Return a hashcode representing this Object.
     * <code>Float</code>'s hash code is calculated by calling the
     * <code>floatToIntBits()</code> function.
     * @return this Object's hash code.
     * @see java.lang.Float.floatToIntBits(float)
     */    
    public int hashCode() 
    {
	return floatToIntBits(value);
    }
    /**
     * 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;
    }
    
    /**
     * Convert the <code>float</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 f the <code>float</code> to convert
     * @return the <code>String</code> representing the <code>float</code>.
     */
    public native static String toString(float f);

    /**
     * Return the result of calling <code>new Float(java.lang.String)</code>.
     *
     * @param s the <code>String</code> to convert to a <code>Float</code>.
     * @return a new <code>Float</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 #Float(java.lang.String)
     * @see #parseFloat(java.lang.String)
     */
    public static Float valueOf(String s)
	throws NumberFormatException, NullPointerException
    {
	return new Float(s);
    }
    
    /**
     * Return <code>true</code> if the value of this <code>Float</code>
     * is the same as <code>NaN</code>, otherwise return <code>false</code>.
     * @return whether this <code>Float</code> is <code>NaN</code>.
     */
    public boolean isNaN() 
    {
	return isNaN(value);
    }

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

    }

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

    /**
     * Convert the float to the IEEE 754 floating-point "single format" bit
     * layout. Bit 31 (the most significant) is the sign bit, bits 30-23
     * (masked by 0x7f800000) represent the exponent, and bits 22-0
     * (masked by 0x007fffff) are the mantissa. This function collapses all
     * versions of NaN to 0x7fc00000. The result of this function can be used
     * as the argument to <code>Float.intBitsToFloat(int)</code> to obtain the
     * original <code>float</code> value.
     *
     * @param value the <code>float</code> to convert
     * @return the bits of the <code>float</code>
     * @see #intBitsToFloat(int)
     */
    public static int floatToIntBits(float value) {
        if (Float.isNaN(value)) return 0x7fc0000;
        // do we need to check +/- infinity ?
        return floatToRawIntBits(value);
    }

    /**
     * Convert the float to the IEEE 754 floating-point "single format" bit
     * layout. Bit 31 (the most significant) is the sign bit, bits 30-23
     * (masked by 0x7f800000) represent the exponent, and bits 22-0
     * (masked by 0x007fffff) 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>Float.intBitsToFloat(int)</code> to
     * obtain the original <code>float</code> value.
     *
     * @param value the <code>float</code> to convert
     * @return the bits of the <code>float</code>
     * @see #intBitsToFloat(int)
     */
    public static int floatToRawIntBits(float value)
        throws VM_Address.BCfiatret {
        return /* hosted only */ 0;
    }


    /**
     * Convert the argument in IEEE 754 floating-point "single format" bit
     * layout to the corresponding float. Bit 31 (the most significant) is the
     * sign bit, bits 30-23 (masked by 0x7f800000) represent the exponent, and
     * bits 22-0 (masked by 0x007fffff) are the mantissa. This function leaves
     * NaN alone, so that you can recover the bit pattern with
     * <code>Float.floatToRawIntBits(float)</code>.
     *
     * @param bits the bits to convert
     * @return the <code>float</code> represented by the bits
     * @see #floatToIntBits(float)
     * @see #floatToRawIntBits(float)
     */
    public static float intBitsToFloat(int bits) 
        throws VM_Address.BCfiatret {
        return /* hosted only */ 0;
    }


    /**
     * Parse the specified <code>String</code> as a <code>float</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>float</code> has a limited range.  If the
     * number you specify is greater than <code>Float.MAX_VALUE</code> or less
     * than <code>-Float.MAX_VALUE</code>, it will be set at
     * <code>Float.POSITIVE_INFINITY</code> or
     * <code>Float.NEGATIVE_INFINITY</code>, respectively.
     * <P>
     *
     * Note also that <code>float</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>Float.MIN_VALUE</code> is
     * the margin of error for <code>float</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 this exception to be thrown.
     *
     * @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>float</code>.
     * @exception NumberFormatException when the string cannot be parsed to a
     *            <code>float</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 float parseFloat(String s)
    throws NumberFormatException, NullPointerException;
}
