| /* |
| * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved. |
| * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. |
| * |
| * This code is free software; you can redistribute it and/or modify it |
| * under the terms of the GNU General Public License version 2 only, as |
| * published by the Free Software Foundation. Oracle designates this |
| * particular file as subject to the "Classpath" exception as provided |
| * by Oracle in the LICENSE file that accompanied this code. |
| * |
| * This code 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 |
| * version 2 for more details (a copy is included in the LICENSE file that |
| * accompanied this code). |
| * |
| * You should have received a copy of the GNU General Public License version |
| * 2 along with this work; if not, write to the Free Software Foundation, |
| * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. |
| * |
| * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA |
| * or visit www.oracle.com if you need additional information or have any |
| * questions. |
| */ |
| |
| // This file is available under and governed by the GNU General Public |
| // License version 2 only, as published by the Free Software Foundation. |
| // However, the following notice accompanied the original version of this |
| // file: |
| // |
| // Copyright 2010 the V8 project authors. All rights reserved. |
| // Redistribution and use in source and binary forms, with or without |
| // modification, are permitted provided that the following conditions are |
| // met: |
| // |
| // * Redistributions of source code must retain the above copyright |
| // notice, this list of conditions and the following disclaimer. |
| // * Redistributions in binary form must reproduce the above |
| // copyright notice, this list of conditions and the following |
| // disclaimer in the documentation and/or other materials provided |
| // with the distribution. |
| // * Neither the name of Google Inc. nor the names of its |
| // contributors may be used to endorse or promote products derived |
| // from this software without specific prior written permission. |
| // |
| // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| package jdk.nashorn.internal.runtime.doubleconv; |
| |
| // Helper functions for doubles. |
| class IeeeDouble { |
| |
| // We assume that doubles and long have the same endianness. |
| static long doubleToLong(final double d) { return Double.doubleToRawLongBits(d); } |
| static double longToDouble(final long d64) { return Double.longBitsToDouble(d64); } |
| |
| static final long kSignMask = 0x8000000000000000L; |
| static final long kExponentMask = 0x7FF0000000000000L; |
| static final long kSignificandMask = 0x000FFFFFFFFFFFFFL; |
| static final long kHiddenBit = 0x0010000000000000L; |
| static final int kPhysicalSignificandSize = 52; // Excludes the hidden bit. |
| static final int kSignificandSize = 53; |
| |
| static private final int kExponentBias = 0x3FF + kPhysicalSignificandSize; |
| static private final int kDenormalExponent = -kExponentBias + 1; |
| static private final int kMaxExponent = 0x7FF - kExponentBias; |
| static private final long kInfinity = 0x7FF0000000000000L; |
| static private final long kNaN = 0x7FF8000000000000L; |
| |
| static DiyFp asDiyFp(final long d64) { |
| assert (!isSpecial(d64)); |
| return new DiyFp(significand(d64), exponent(d64)); |
| } |
| |
| // The value encoded by this Double must be strictly greater than 0. |
| static DiyFp asNormalizedDiyFp(final long d64) { |
| assert (value(d64) > 0.0); |
| long f = significand(d64); |
| int e = exponent(d64); |
| |
| // The current double could be a denormal. |
| while ((f & kHiddenBit) == 0) { |
| f <<= 1; |
| e--; |
| } |
| // Do the final shifts in one go. |
| f <<= DiyFp.kSignificandSize - kSignificandSize; |
| e -= DiyFp.kSignificandSize - kSignificandSize; |
| |
| return new DiyFp(f, e); |
| } |
| |
| // Returns the next greater double. Returns +infinity on input +infinity. |
| static double nextDouble(final long d64) { |
| if (d64 == kInfinity) return longToDouble(kInfinity); |
| if (sign(d64) < 0 && significand(d64) == 0) { |
| // -0.0 |
| return 0.0; |
| } |
| if (sign(d64) < 0) { |
| return longToDouble(d64 - 1); |
| } else { |
| return longToDouble(d64 + 1); |
| } |
| } |
| |
| static double previousDouble(final long d64) { |
| if (d64 == (kInfinity | kSignMask)) return -Infinity(); |
| if (sign(d64) < 0) { |
| return longToDouble(d64 + 1); |
| } else { |
| if (significand(d64) == 0) return -0.0; |
| return longToDouble(d64 - 1); |
| } |
| } |
| |
| static int exponent(final long d64) { |
| if (isDenormal(d64)) return kDenormalExponent; |
| |
| final int biased_e = (int) ((d64 & kExponentMask) >>> kPhysicalSignificandSize); |
| return biased_e - kExponentBias; |
| } |
| |
| static long significand(final long d64) { |
| final long significand = d64 & kSignificandMask; |
| if (!isDenormal(d64)) { |
| return significand + kHiddenBit; |
| } else { |
| return significand; |
| } |
| } |
| |
| // Returns true if the double is a denormal. |
| static boolean isDenormal(final long d64) { |
| return (d64 & kExponentMask) == 0L; |
| } |
| |
| // We consider denormals not to be special. |
| // Hence only Infinity and NaN are special. |
| static boolean isSpecial(final long d64) { |
| return (d64 & kExponentMask) == kExponentMask; |
| } |
| |
| static boolean isNaN(final long d64) { |
| return ((d64 & kExponentMask) == kExponentMask) && |
| ((d64 & kSignificandMask) != 0L); |
| } |
| |
| |
| static boolean isInfinite(final long d64) { |
| return ((d64 & kExponentMask) == kExponentMask) && |
| ((d64 & kSignificandMask) == 0L); |
| } |
| |
| |
| static int sign(final long d64) { |
| return (d64 & kSignMask) == 0L ? 1 : -1; |
| } |
| |
| |
| // Computes the two boundaries of this. |
| // The bigger boundary (m_plus) is normalized. The lower boundary has the same |
| // exponent as m_plus. |
| // Precondition: the value encoded by this Double must be greater than 0. |
| static void normalizedBoundaries(final long d64, final DiyFp m_minus, final DiyFp m_plus) { |
| assert (value(d64) > 0.0); |
| final DiyFp v = asDiyFp(d64); |
| m_plus.setF((v.f() << 1) + 1); |
| m_plus.setE(v.e() - 1); |
| m_plus.normalize(); |
| if (lowerBoundaryIsCloser(d64)) { |
| m_minus.setF((v.f() << 2) - 1); |
| m_minus.setE(v.e() - 2); |
| } else { |
| m_minus.setF((v.f() << 1) - 1); |
| m_minus.setE(v.e() - 1); |
| } |
| m_minus.setF(m_minus.f() << (m_minus.e() - m_plus.e())); |
| m_minus.setE(m_plus.e()); |
| } |
| |
| static boolean lowerBoundaryIsCloser(final long d64) { |
| // The boundary is closer if the significand is of the form f == 2^p-1 then |
| // the lower boundary is closer. |
| // Think of v = 1000e10 and v- = 9999e9. |
| // Then the boundary (== (v - v-)/2) is not just at a distance of 1e9 but |
| // at a distance of 1e8. |
| // The only exception is for the smallest normal: the largest denormal is |
| // at the same distance as its successor. |
| // Note: denormals have the same exponent as the smallest normals. |
| final boolean physical_significand_is_zero = ((d64 & kSignificandMask) == 0); |
| return physical_significand_is_zero && (exponent(d64) != kDenormalExponent); |
| } |
| |
| static double value(final long d64) { |
| return longToDouble(d64); |
| } |
| |
| // Returns the significand size for a given order of magnitude. |
| // If v = f*2^e with 2^p-1 <= f <= 2^p then p+e is v's order of magnitude. |
| // This function returns the number of significant binary digits v will have |
| // once it's encoded into a double. In almost all cases this is equal to |
| // kSignificandSize. The only exceptions are denormals. They start with |
| // leading zeroes and their effective significand-size is hence smaller. |
| static int significandSizeForOrderOfMagnitude(final int order) { |
| if (order >= (kDenormalExponent + kSignificandSize)) { |
| return kSignificandSize; |
| } |
| if (order <= kDenormalExponent) return 0; |
| return order - kDenormalExponent; |
| } |
| |
| static double Infinity() { |
| return longToDouble(kInfinity); |
| } |
| |
| static double NaN() { |
| return longToDouble(kNaN); |
| } |
| |
| } |
| |
| |
