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double-conversion-ieee.h (15734B)

---

// © 2018 and later: Unicode, Inc. and others.
// License & terms of use: http://www.unicode.org/copyright.html
//
// From the double-conversion library. Original license:
//
// Copyright 2012 the V8 project authors. All rights reserved.
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// modification, are permitted provided that the following conditions are
// met:
//
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// ICU PATCH: ifdef around UCONFIG_NO_FORMATTING
#include "unicode/utypes.h"
#if !UCONFIG_NO_FORMATTING

#ifndef DOUBLE_CONVERSION_DOUBLE_H_
#define DOUBLE_CONVERSION_DOUBLE_H_

// ICU PATCH: Customize header file paths for ICU.

#include "double-conversion-diy-fp.h"

// ICU PATCH: Wrap in ICU namespace
U_NAMESPACE_BEGIN

namespace double_conversion {

// We assume that doubles and uint64_t have the same endianness.
static uint64_t double_to_uint64(double d) { return BitCast<uint64_t>(d); }
static double uint64_to_double(uint64_t d64) { return BitCast<double>(d64); }
static uint32_t float_to_uint32(float f) { return BitCast<uint32_t>(f); }
static float uint32_to_float(uint32_t d32) { return BitCast<float>(d32); }

// Helper functions for doubles.
class Double {
public:
 static const uint64_t kSignMask = DOUBLE_CONVERSION_UINT64_2PART_C(0x80000000, 00000000);
 static const uint64_t kExponentMask = DOUBLE_CONVERSION_UINT64_2PART_C(0x7FF00000, 00000000);
 static const uint64_t kSignificandMask = DOUBLE_CONVERSION_UINT64_2PART_C(0x000FFFFF, FFFFFFFF);
 static const uint64_t kHiddenBit = DOUBLE_CONVERSION_UINT64_2PART_C(0x00100000, 00000000);
 static const uint64_t kQuietNanBit = DOUBLE_CONVERSION_UINT64_2PART_C(0x00080000, 00000000);
 static const int kPhysicalSignificandSize = 52;  // Excludes the hidden bit.
 static const int kSignificandSize = 53;
 static const int kExponentBias = 0x3FF + kPhysicalSignificandSize;
 static const int kMaxExponent = 0x7FF - kExponentBias;

 Double() : d64_(0) {}
 explicit Double(double d) : d64_(double_to_uint64(d)) {}
 explicit Double(uint64_t d64) : d64_(d64) {}
 explicit Double(DiyFp diy_fp)
   : d64_(DiyFpToUint64(diy_fp)) {}

 // The value encoded by this Double must be greater or equal to +0.0.
 // It must not be special (infinity, or NaN).
 DiyFp AsDiyFp() const {
   DOUBLE_CONVERSION_ASSERT(Sign() > 0);
   DOUBLE_CONVERSION_ASSERT(!IsSpecial());
   return DiyFp(Significand(), Exponent());
 }

 // The value encoded by this Double must be strictly greater than 0.
 DiyFp AsNormalizedDiyFp() const {
   DOUBLE_CONVERSION_ASSERT(value() > 0.0);
   uint64_t f = Significand();
   int e = Exponent();

   // 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 DiyFp(f, e);
 }

 // Returns the double's bit as uint64.
 uint64_t AsUint64() const {
   return d64_;
 }

 // Returns the next greater double. Returns +infinity on input +infinity.
 double NextDouble() const {
   if (d64_ == kInfinity) return Double(kInfinity).value();
   if (Sign() < 0 && Significand() == 0) {
     // -0.0
     return 0.0;
   }
   if (Sign() < 0) {
     return Double(d64_ - 1).value();
   } else {
     return Double(d64_ + 1).value();
   }
 }

 double PreviousDouble() const {
   if (d64_ == (kInfinity | kSignMask)) return -Infinity();
   if (Sign() < 0) {
     return Double(d64_ + 1).value();
   } else {
     if (Significand() == 0) return -0.0;
     return Double(d64_ - 1).value();
   }
 }

 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;
 }

 bool IsNan() const {
   uint64_t d64 = AsUint64();
   return ((d64 & kExponentMask) == kExponentMask) &&
       ((d64 & kSignificandMask) != 0);
 }

 bool IsQuietNan() const {
#if (defined(__mips__) && !defined(__mips_nan2008)) || defined(__hppa__)
   return IsNan() && ((AsUint64() & kQuietNanBit) == 0);
#else
   return IsNan() && ((AsUint64() & kQuietNanBit) != 0);
#endif
 }

 bool IsSignalingNan() const {
#if (defined(__mips__) && !defined(__mips_nan2008)) || defined(__hppa__)
   return IsNan() && ((AsUint64() & kQuietNanBit) != 0);
#else
   return IsNan() && ((AsUint64() & kQuietNanBit) == 0);
#endif
 }


 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;
 }

 // Precondition: the value encoded by this Double must be greater or equal
 // than +0.0.
 DiyFp UpperBoundary() const {
   DOUBLE_CONVERSION_ASSERT(Sign() > 0);
   return DiyFp(Significand() * 2 + 1, Exponent() - 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.
 void NormalizedBoundaries(DiyFp* out_m_minus, DiyFp* out_m_plus) const {
   DOUBLE_CONVERSION_ASSERT(value() > 0.0);
   DiyFp v = this->AsDiyFp();
   DiyFp m_plus = DiyFp::Normalize(DiyFp((v.f() << 1) + 1, v.e() - 1));
   DiyFp m_minus;
   if (LowerBoundaryIsCloser()) {
     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;
 }

 bool LowerBoundaryIsCloser() const {
   // 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.
   bool physical_significand_is_zero = ((AsUint64() & kSignificandMask) == 0);
   return physical_significand_is_zero && (Exponent() != kDenormalExponent);
 }

 double value() const { return uint64_to_double(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(int order) {
   if (order >= (kDenormalExponent + kSignificandSize)) {
     return kSignificandSize;
   }
   if (order <= kDenormalExponent) return 0;
   return order - kDenormalExponent;
 }

 static double Infinity() {
   return Double(kInfinity).value();
 }

 static double NaN() {
   return Double(kNaN).value();
 }

private:
 static const int kDenormalExponent = -kExponentBias + 1;
 static const uint64_t kInfinity = DOUBLE_CONVERSION_UINT64_2PART_C(0x7FF00000, 00000000);
#if (defined(__mips__) && !defined(__mips_nan2008)) || defined(__hppa__)
 static const uint64_t kNaN = DOUBLE_CONVERSION_UINT64_2PART_C(0x7FF7FFFF, FFFFFFFF);
#else
 static const uint64_t kNaN = DOUBLE_CONVERSION_UINT64_2PART_C(0x7FF80000, 00000000);
#endif


 const uint64_t d64_;

 static uint64_t DiyFpToUint64(DiyFp diy_fp) {
   uint64_t significand = diy_fp.f();
   int exponent = diy_fp.e();
   while (significand > kHiddenBit + kSignificandMask) {
     significand >>= 1;
     exponent++;
   }
   if (exponent >= kMaxExponent) {
     return kInfinity;
   }
   if (exponent < kDenormalExponent) {
     return 0;
   }
   while (exponent > kDenormalExponent && (significand & kHiddenBit) == 0) {
     significand <<= 1;
     exponent--;
   }
   uint64_t biased_exponent;
   if (exponent == kDenormalExponent && (significand & kHiddenBit) == 0) {
     biased_exponent = 0;
   } else {
     biased_exponent = static_cast<uint64_t>(exponent + kExponentBias);
   }
   return (significand & kSignificandMask) |
       (biased_exponent << kPhysicalSignificandSize);
 }

 DOUBLE_CONVERSION_DISALLOW_COPY_AND_ASSIGN(Double);
};

class Single {
public:
 static const uint32_t kSignMask = 0x80000000;
 static const uint32_t kExponentMask = 0x7F800000;
 static const uint32_t kSignificandMask = 0x007FFFFF;
 static const uint32_t kHiddenBit = 0x00800000;
 static const uint32_t kQuietNanBit = 0x00400000;
 static const int kPhysicalSignificandSize = 23;  // Excludes the hidden bit.
 static const int kSignificandSize = 24;

 Single() : d32_(0) {}
 explicit Single(float f) : d32_(float_to_uint32(f)) {}
 explicit Single(uint32_t d32) : d32_(d32) {}

 // The value encoded by this Single must be greater or equal to +0.0.
 // It must not be special (infinity, or NaN).
 DiyFp AsDiyFp() const {
   DOUBLE_CONVERSION_ASSERT(Sign() > 0);
   DOUBLE_CONVERSION_ASSERT(!IsSpecial());
   return DiyFp(Significand(), Exponent());
 }

 // Returns the single's bit as uint64.
 uint32_t AsUint32() const {
   return d32_;
 }

 int Exponent() const {
   if (IsDenormal()) return kDenormalExponent;

   uint32_t d32 = AsUint32();
   int biased_e =
       static_cast<int>((d32 & kExponentMask) >> kPhysicalSignificandSize);
   return biased_e - kExponentBias;
 }

 uint32_t Significand() const {
   uint32_t d32 = AsUint32();
   uint32_t significand = d32 & kSignificandMask;
   if (!IsDenormal()) {
     return significand + kHiddenBit;
   } else {
     return significand;
   }
 }

 // Returns true if the single is a denormal.
 bool IsDenormal() const {
   uint32_t d32 = AsUint32();
   return (d32 & kExponentMask) == 0;
 }

 // We consider denormals not to be special.
 // Hence only Infinity and NaN are special.
 bool IsSpecial() const {
   uint32_t d32 = AsUint32();
   return (d32 & kExponentMask) == kExponentMask;
 }

 bool IsNan() const {
   uint32_t d32 = AsUint32();
   return ((d32 & kExponentMask) == kExponentMask) &&
       ((d32 & kSignificandMask) != 0);
 }

 bool IsQuietNan() const {
#if (defined(__mips__) && !defined(__mips_nan2008)) || defined(__hppa__)
   return IsNan() && ((AsUint32() & kQuietNanBit) == 0);
#else
   return IsNan() && ((AsUint32() & kQuietNanBit) != 0);
#endif
 }

 bool IsSignalingNan() const {
#if (defined(__mips__) && !defined(__mips_nan2008)) || defined(__hppa__)
   return IsNan() && ((AsUint32() & kQuietNanBit) != 0);
#else
   return IsNan() && ((AsUint32() & kQuietNanBit) == 0);
#endif
 }


 bool IsInfinite() const {
   uint32_t d32 = AsUint32();
   return ((d32 & kExponentMask) == kExponentMask) &&
       ((d32 & kSignificandMask) == 0);
 }

 int Sign() const {
   uint32_t d32 = AsUint32();
   return (d32 & kSignMask) == 0? 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 Single must be greater than 0.
 void NormalizedBoundaries(DiyFp* out_m_minus, DiyFp* out_m_plus) const {
   DOUBLE_CONVERSION_ASSERT(value() > 0.0);
   DiyFp v = this->AsDiyFp();
   DiyFp m_plus = DiyFp::Normalize(DiyFp((v.f() << 1) + 1, v.e() - 1));
   DiyFp m_minus;
   if (LowerBoundaryIsCloser()) {
     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;
 }

 // Precondition: the value encoded by this Single must be greater or equal
 // than +0.0.
 DiyFp UpperBoundary() const {
   DOUBLE_CONVERSION_ASSERT(Sign() > 0);
   return DiyFp(Significand() * 2 + 1, Exponent() - 1);
 }

 bool LowerBoundaryIsCloser() const {
   // 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.
   bool physical_significand_is_zero = ((AsUint32() & kSignificandMask) == 0);
   return physical_significand_is_zero && (Exponent() != kDenormalExponent);
 }

 float value() const { return uint32_to_float(d32_); }

 static float Infinity() {
   return Single(kInfinity).value();
 }

 static float NaN() {
   return Single(kNaN).value();
 }

private:
 static const int kExponentBias = 0x7F + kPhysicalSignificandSize;
 static const int kDenormalExponent = -kExponentBias + 1;
 static const int kMaxExponent = 0xFF - kExponentBias;
 static const uint32_t kInfinity = 0x7F800000;
#if (defined(__mips__) && !defined(__mips_nan2008)) || defined(__hppa__)
 static const uint32_t kNaN = 0x7FBFFFFF;
#else
 static const uint32_t kNaN = 0x7FC00000;
#endif

 const uint32_t d32_;

 DOUBLE_CONVERSION_DISALLOW_COPY_AND_ASSIGN(Single);
};

}  // namespace double_conversion

// ICU PATCH: Close ICU namespace
U_NAMESPACE_END

#endif  // DOUBLE_CONVERSION_DOUBLE_H_
#endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING