| // Copyright (c) 2012, the Dart project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| |
| #ifndef RUNTIME_VM_DOUBLE_INTERNALS_H_ |
| #define RUNTIME_VM_DOUBLE_INTERNALS_H_ |
| |
| #include "platform/utils.h" |
| |
| namespace dart { |
| |
| // 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); |
| } |
| |
| // Helper functions for doubles. |
| class DoubleInternals { |
| public: |
| static constexpr int kSignificandSize = 53; |
| |
| explicit DoubleInternals(double d) : d64_(double_to_uint64(d)) {} |
| |
| // 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 = |
| static_cast<int>((d64 & kExponentMask) >> kPhysicalSignificandSize); |
| 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; |
| } |
| |
| int Sign() const { |
| uint64_t d64 = AsUint64(); |
| return (d64 & kSignMask) == 0 ? 1 : -1; |
| } |
| |
| private: |
| static constexpr uint64_t kSignMask = |
| DART_2PART_UINT64_C(0x80000000, 00000000); |
| static constexpr uint64_t kExponentMask = |
| DART_2PART_UINT64_C(0x7FF00000, 00000000); |
| static constexpr uint64_t kSignificandMask = |
| DART_2PART_UINT64_C(0x000FFFFF, FFFFFFFF); |
| static constexpr uint64_t kHiddenBit = |
| DART_2PART_UINT64_C(0x00100000, 00000000); |
| static constexpr int kPhysicalSignificandSize = |
| 52; // Excludes the hidden bit. |
| static constexpr int kExponentBias = 0x3FF + kPhysicalSignificandSize; |
| static constexpr int kDenormalExponent = -kExponentBias + 1; |
| |
| const uint64_t d64_; |
| }; |
| |
| } // namespace dart |
| |
| #endif // RUNTIME_VM_DOUBLE_INTERNALS_H_ |