1 /* 2 * Copyright (c) 2003, 2022, 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. Oracle designates this 8 * particular file as subject to the "Classpath" exception as provided 9 * by Oracle in the LICENSE file that accompanied this code. 10 * 11 * This code is distributed in the hope that it will be useful, but WITHOUT 12 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 13 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 14 * version 2 for more details (a copy is included in the LICENSE file that 15 * accompanied this code). 16 * 17 * You should have received a copy of the GNU General Public License version 18 * 2 along with this work; if not, write to the Free Software Foundation, 19 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 20 * 21 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 22 * or visit www.oracle.com if you need additional information or have any 23 * questions. 24 */ 25 26 package jdk.internal.math; 27 28 import static java.lang.Float.MIN_EXPONENT; 29 import static java.lang.Float.PRECISION; 30 import static java.lang.Float.SIZE; 31 32 /** 33 * This class contains additional constants documenting limits of the 34 * {@code float} type. 35 * 36 * @author Joseph D. Darcy 37 */ 38 39 public class FloatConsts { 40 /** 41 * Don't let anyone instantiate this class. 42 */ FloatConsts()43 private FloatConsts() {} 44 45 public static final float POSITIVE_INFINITY = java.lang.Float.POSITIVE_INFINITY; 46 public static final float NEGATIVE_INFINITY = java.lang.Float.NEGATIVE_INFINITY; 47 public static final float NaN = java.lang.Float.NaN; 48 public static final float MAX_VALUE = java.lang.Float.MAX_VALUE; 49 public static final float MIN_VALUE = java.lang.Float.MIN_VALUE; 50 51 /** 52 * A constant holding the smallest positive normal value of type 53 * <code>float</code>, 2<sup>-126</sup>. It is equal to the value 54 * returned by <code>Float.intBitsToFloat(0x00800000)</code>. 55 */ 56 public static final float MIN_NORMAL = 1.17549435E-38f; 57 58 /** 59 * The number of logical bits in the significand of a 60 * {@code float} number, including the implicit bit. 61 */ 62 public static final int SIGNIFICAND_WIDTH = PRECISION; 63 64 /** 65 * Maximum exponent a finite <code>float</code> number may have. 66 * It is equal to the value returned by 67 * <code>Math.ilogb(Float.MAX_VALUE)</code>. 68 */ 69 public static final int MAX_EXPONENT = 127; 70 71 /** 72 * Minimum exponent a normalized <code>float</code> number may 73 * have. It is equal to the value returned by 74 * <code>Math.ilogb(Float.MIN_NORMAL)</code>. 75 */ 76 public static final int MIN_EXPONENT = -126; 77 78 /** 79 * The exponent the smallest positive {@code float} 80 * subnormal value would have if it could be normalized. 81 */ 82 public static final int MIN_SUB_EXPONENT = 83 MIN_EXPONENT - (SIGNIFICAND_WIDTH - 1); // -149 84 85 /** 86 * Bias used in representing a {@code float} exponent. 87 */ 88 public static final int EXP_BIAS = 89 (1 << (SIZE - SIGNIFICAND_WIDTH - 1)) - 1; // 127 90 91 /** 92 * Bit mask to isolate the sign bit of a {@code float}. 93 */ 94 public static final int SIGN_BIT_MASK = 1 << (SIZE - 1); 95 96 /** 97 * Bit mask to isolate the exponent field of a {@code float}. 98 */ 99 public static final int EXP_BIT_MASK = 100 ((1 << (SIZE - SIGNIFICAND_WIDTH)) - 1) << (SIGNIFICAND_WIDTH - 1); 101 102 /** 103 * Bit mask to isolate the significand field of a {@code float}. 104 */ 105 public static final int SIGNIF_BIT_MASK = (1 << (SIGNIFICAND_WIDTH - 1)) - 1; 106 107 /** 108 * Bit mask to isolate the magnitude bits (combined exponent and 109 * significand fields) of a {@code float}. 110 */ 111 public static final int MAG_BIT_MASK = EXP_BIT_MASK | SIGNIF_BIT_MASK; 112 113 static { 114 // verify bit masks cover all bit positions and that the bit 115 // masks are non-overlapping 116 assert(((SIGN_BIT_MASK | EXP_BIT_MASK | SIGNIF_BIT_MASK) == ~0) && 117 (((SIGN_BIT_MASK & EXP_BIT_MASK) == 0) && 118 ((SIGN_BIT_MASK & SIGNIF_BIT_MASK) == 0) && 119 ((EXP_BIT_MASK & SIGNIF_BIT_MASK) == 0)) && 120 ((SIGN_BIT_MASK | MAG_BIT_MASK) == ~0)); 121 } 122 } 123