text: // © 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 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,
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  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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  // 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.
  
  // ICU PATCH: ifdef around UCONFIG_NO_FORMATTING
  #include "unicode/utypes.h"
  #if !UCONFIG_NO_FORMATTING
  
  #ifndef DOUBLE_CONVERSION_BIGNUM_H_
  #define DOUBLE_CONVERSION_BIGNUM_H_
  
  // ICU PATCH: Customize header file paths for ICU.
  
  #include "double-conversion-utils.h"
  
  // ICU PATCH: Wrap in ICU namespace
  U_NAMESPACE_BEGIN
  
  namespace double_conversion {
  
  class Bignum {
   public:
    // 3584 = 128 * 28. We can represent 2^3584 > 10^1000 accurately.
    // This bignum can encode much bigger numbers, since it contains an
    // exponent.
    static const int kMaxSignificantBits = 3584;
  
    Bignum();
    void AssignUInt16(uint16_t value);
    void AssignUInt64(uint64_t value);
    void AssignBignum(const Bignum& other);
  
    void AssignDecimalString(Vector<const char> value);
    void AssignHexString(Vector<const char> value);
  
    void AssignPowerUInt16(uint16_t base, int exponent);
  
    void AddUInt64(uint64_t operand);
    void AddBignum(const Bignum& other);
    // Precondition: this >= other.
    void SubtractBignum(const Bignum& other);
  
    void Square();
    void ShiftLeft(int shift_amount);
    void MultiplyByUInt32(uint32_t factor);
    void MultiplyByUInt64(uint64_t factor);
    void MultiplyByPowerOfTen(int exponent);
    void Times10() { return MultiplyByUInt32(10); }
    // Pseudocode:
    //  int result = this / other;
    //  this = this % other;
    // In the worst case this function is in O(this/other).
    uint16_t DivideModuloIntBignum(const Bignum& other);
  
    bool ToHexString(char* buffer, int buffer_size) const;
  
    // Returns
    //  -1 if a < b,
    //   0 if a == b, and
    //  +1 if a > b.
    static int Compare(const Bignum& a, const Bignum& b);
    static bool Equal(const Bignum& a, const Bignum& b) {
      return Compare(a, b) == 0;
    }
    static bool LessEqual(const Bignum& a, const Bignum& b) {
      return Compare(a, b) <= 0;
    }
    static bool Less(const Bignum& a, const Bignum& b) {
      return Compare(a, b) < 0;
    }
    // Returns Compare(a + b, c);
    static int PlusCompare(const Bignum& a, const Bignum& b, const Bignum& c);
    // Returns a + b == c
    static bool PlusEqual(const Bignum& a, const Bignum& b, const Bignum& c) {
      return PlusCompare(a, b, c) == 0;
    }
    // Returns a + b <= c
    static bool PlusLessEqual(const Bignum& a, const Bignum& b, const Bignum& c) {
      return PlusCompare(a, b, c) <= 0;
    }
    // Returns a + b < c
    static bool PlusLess(const Bignum& a, const Bignum& b, const Bignum& c) {
      return PlusCompare(a, b, c) < 0;
    }
   private:
    typedef uint32_t Chunk;
    typedef uint64_t DoubleChunk;
  
    static const int kChunkSize = sizeof(Chunk) * 8;
    static const int kDoubleChunkSize = sizeof(DoubleChunk) * 8;
    // With bigit size of 28 we loose some bits, but a double still fits easily
    // into two chunks, and more importantly we can use the Comba multiplication.
    static const int kBigitSize = 28;
    static const Chunk kBigitMask = (1 << kBigitSize) - 1;
    // Every instance allocates kBigitLength chunks on the stack. Bignums cannot
    // grow. There are no checks if the stack-allocated space is sufficient.
    static const int kBigitCapacity = kMaxSignificantBits / kBigitSize;
  
    void EnsureCapacity(int size) {
      if (size > kBigitCapacity) {
        UNREACHABLE();
      }
    }
    void Align(const Bignum& other);
    void Clamp();
    bool IsClamped() const;
    void Zero();
    // Requires this to have enough capacity (no tests done).
    // Updates used_digits_ if necessary.
    // shift_amount must be < kBigitSize.
    void BigitsShiftLeft(int shift_amount);
    // BigitLength includes the "hidden" digits encoded in the exponent.
    int BigitLength() const { return used_digits_ + exponent_; }
    Chunk BigitAt(int index) const;
    void SubtractTimes(const Bignum& other, int factor);
  
    Chunk bigits_buffer_[kBigitCapacity];
    // A vector backed by bigits_buffer_. This way accesses to the array are
    // checked for out-of-bounds errors.
    Vector<Chunk> bigits_;
    int used_digits_;
    // The Bignum's value equals value(bigits_) * 2^(exponent_ * kBigitSize).
    int exponent_;
  
    DISALLOW_COPY_AND_ASSIGN(Bignum);
  };
  
  }  // namespace double_conversion
  
  // ICU PATCH: Close ICU namespace
  U_NAMESPACE_END
  
  #endif  // DOUBLE_CONVERSION_BIGNUM_H_
  #endif // ICU PATCH: close #if !UCONFIG_NO_FORMATTING
  