1 /*
   2  * Copyright (c) 2003, 2014, Oracle and/or its affiliates. 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.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  */
  23 
  24 /**
  25  * Common library for additional constants of the {@code double} type.
  26  */
  27 public final class DoubleConsts {
  28     /**
  29      * Don't let anyone instantiate this class.
  30      */
  31     private DoubleConsts() {}
  32 
  33     /**
  34      * Bias used in representing a {@code double} exponent.
  35      */
  36     public static final int     EXP_BIAS        = 1023;
  37 
  38     /**
  39      * Bit mask to isolate the exponent field of a {@code double}.
  40      */
  41     public static final long    EXP_BIT_MASK    = 0x7FF0000000000000L;
  42 
  43     /**
  44      * Bit mask to isolate the sign bit of a {@code double}.
  45      */
  46     public static final long    SIGN_BIT_MASK   = 0x8000000000000000L;
  47 
  48     /**
  49      * Bit mask to isolate the significand field of a {@code double}.
  50      */
  51     public static final long    SIGNIF_BIT_MASK = 0x000FFFFFFFFFFFFFL;
  52 
  53     /**
  54      * The number of logical bits in the significand of a
  55      * {@code double} number, including the implicit bit.
  56      */
  57     public static final int SIGNIFICAND_WIDTH   = 53;
  58 
  59     /**
  60      * The exponent the smallest positive {@code double}
  61      * subnormal value would have if it could be normalized.
  62      */
  63     public static final int     MIN_SUB_EXPONENT = Double.MIN_EXPONENT -
  64                                                    (SIGNIFICAND_WIDTH - 1);
  65 
  66     static {
  67         // verify bit masks cover all bit positions and that the bit
  68         // masks are non-overlapping
  69         assert(((SIGN_BIT_MASK | EXP_BIT_MASK | SIGNIF_BIT_MASK) == ~0L) &&
  70                (((SIGN_BIT_MASK & EXP_BIT_MASK) == 0L) &&
  71                 ((SIGN_BIT_MASK & SIGNIF_BIT_MASK) == 0L) &&
  72                 ((EXP_BIT_MASK & SIGNIF_BIT_MASK) == 0L)));
  73     }
  74 }