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Unified Diff: src/double.h

Issue 804005: Revert grisu commits. (Closed) Base URL: http://v8.googlecode.com/svn/branches/bleeding_edge/
Patch Set: Created 10 years, 9 months ago
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Index: src/double.h
===================================================================
--- src/double.h (revision 4091)
+++ src/double.h (working copy)
@@ -1,169 +0,0 @@
-// 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.
-
-#ifndef V8_DOUBLE_H_
-#define V8_DOUBLE_H_
-
-#include "diy_fp.h"
-
-namespace v8 {
-namespace internal {
-
-// We assume that doubles and uint64_t have the same endianness.
-static uint64_t double_to_uint64(double d) { return bit_cast<uint64_t>(d); }
-static double uint64_to_double(uint64_t d64) { return bit_cast<double>(d64); }
-
-// Helper functions for doubles.
-class Double {
- public:
- static const uint64_t kSignMask = V8_2PART_UINT64_C(0x80000000, 00000000);
- static const uint64_t kExponentMask = V8_2PART_UINT64_C(0x7FF00000, 00000000);
- static const uint64_t kSignificandMask =
- V8_2PART_UINT64_C(0x000FFFFF, FFFFFFFF);
- static const uint64_t kHiddenBit = V8_2PART_UINT64_C(0x00100000, 00000000);
-
- Double() : d64_(0.0) {}
- explicit Double(double d) : d64_(double_to_uint64(d)) {}
- explicit Double(uint64_t d64) : d64_(d64) {}
-
- DiyFp AsDiyFp() const {
- ASSERT(!IsSpecial());
- return DiyFp(Significand(), Exponent());
- }
-
- // this->Significand() must not be 0.
- DiyFp AsNormalizedDiyFp() const {
- uint64_t f = Significand();
- int e = Exponent();
-
- ASSERT(f != 0);
-
- // The current double could be a denormal.
- while ((f & kHiddenBit) == 0) {
- f <<= 1;
- e--;
- }
- // Do the final shifts in one go. Don't forget the hidden bit (the '-1').
- f <<= DiyFp::kSignificandSize - kSignificandSize - 1;
- e -= DiyFp::kSignificandSize - kSignificandSize - 1;
- return DiyFp(f, e);
- }
-
- // Returns the double's bit as uint64.
- uint64_t AsUint64() const {
- return d64_;
- }
-
- int Exponent() const {
- if (IsDenormal()) return kDenormalExponent;
-
- uint64_t d64 = AsUint64();
- int biased_e = (d64 & kExponentMask) >> kSignificandSize;
- return biased_e - kExponentBias;
- }
-
- uint64_t Significand() const {
- uint64_t d64 = AsUint64();
- uint64_t significand = d64 & kSignificandMask;
- if (!IsDenormal()) {
- return significand + kHiddenBit;
- } else {
- return significand;
- }
- }
-
- // Returns true if the double is a denormal.
- bool IsDenormal() const {
- uint64_t d64 = AsUint64();
- return (d64 & kExponentMask) == 0;
- }
-
- // We consider denormals not to be special.
- // Hence only Infinity and NaN are special.
- bool IsSpecial() const {
- uint64_t d64 = AsUint64();
- return (d64 & kExponentMask) == kExponentMask;
- }
-
- bool IsNan() const {
- uint64_t d64 = AsUint64();
- return ((d64 & kExponentMask) == kExponentMask) &&
- ((d64 & kSignificandMask) != 0);
- }
-
-
- bool IsInfinite() const {
- uint64_t d64 = AsUint64();
- return ((d64 & kExponentMask) == kExponentMask) &&
- ((d64 & kSignificandMask) == 0);
- }
-
-
- int Sign() const {
- uint64_t d64 = AsUint64();
- return (d64 & kSignMask) == 0? 1: -1;
- }
-
-
- // Returns the two boundaries of this.
- // The bigger boundary (m_plus) is normalized. The lower boundary has the same
- // exponent as m_plus.
- void NormalizedBoundaries(DiyFp* out_m_minus, DiyFp* out_m_plus) const {
- DiyFp v = this->AsDiyFp();
- bool significand_is_zero = (v.f() == kHiddenBit);
- DiyFp m_plus = DiyFp::Normalize(DiyFp((v.f() << 1) + 1, v.e() - 1));
- DiyFp m_minus;
- if (significand_is_zero && v.e() != kDenormalExponent) {
- // The 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.
- m_minus = DiyFp((v.f() << 2) - 1, v.e() - 2);
- } else {
- m_minus = DiyFp((v.f() << 1) - 1, v.e() - 1);
- }
- m_minus.set_f(m_minus.f() << (m_minus.e() - m_plus.e()));
- m_minus.set_e(m_plus.e());
- *out_m_plus = m_plus;
- *out_m_minus = m_minus;
- }
-
- double value() const { return uint64_to_double(d64_); }
-
- private:
- static const int kSignificandSize = 52; // Excludes the hidden bit.
- static const int kExponentBias = 0x3FF + kSignificandSize;
- static const int kDenormalExponent = -kExponentBias + 1;
-
- uint64_t d64_;
-};
-
-} } // namespace v8::internal
-
-#endif // V8_DOUBLE_H_
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