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diff --git a/include/jsoncons/bigint.hpp b/include/jsoncons/bigint.hpp
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+++ b/include/jsoncons/bigint.hpp
@@ -0,0 +1,1611 @@
+// Copyright 2018 vDaniel Parker
+// Distributed under the Boost license, Version 1.0.
+// (See accompanying file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
+
+// See https://github.com/danielaparker/jsoncons for latest version
+
+#ifndef JSONCONS_BIGINT_HPP
+#define JSONCONS_BIGINT_HPP
+
+#include <cstdint>
+#include <vector> // std::vector
+#include <iostream>
+#include <climits>
+#include <cassert> // assert
+#include <limits> // std::numeric_limits
+#include <algorithm> // std::max, std::min, std::reverse
+#include <string> // std::string
+#include <cstring> // std::memcpy
+#include <cmath> // std::fmod
+#include <memory> // std::allocator
+#include <initializer_list> // std::initializer_list
+#include <type_traits> // std::enable_if
+#include <jsoncons/config/jsoncons_config.hpp>
+
+namespace jsoncons {
+
+/*
+This implementation is based on Chapter 2 and Appendix A of
+Ammeraal, L. (1996) Algorithms and Data Structures in C++,
+Chichester: John Wiley.
+
+*/
+
+
+namespace detail {
+
+    template <class Allocator>
+    class basic_bigint_base
+    {
+    public:
+        using allocator_type = Allocator;
+        using basic_type_allocator_type = typename std::allocator_traits<allocator_type>:: template rebind_alloc<uint64_t>;
+
+    private:
+        basic_type_allocator_type alloc_;
+    public:
+       using allocator_traits_type = std::allocator_traits<allocator_type>;
+       using stored_allocator_type = allocator_type;
+       using pointer = typename allocator_traits_type::pointer;
+       using value_type = typename allocator_traits_type::value_type;
+       using size_type = typename allocator_traits_type::size_type;
+       using pointer_traits = std::pointer_traits<pointer>;
+
+        basic_bigint_base()
+            : alloc_()
+        {
+        }
+        explicit basic_bigint_base(const allocator_type& alloc)
+            : alloc_(basic_type_allocator_type(alloc))
+        {
+        }
+
+        basic_type_allocator_type get_allocator() const
+        {
+            return alloc_;
+        }
+    };
+
+} // namespace detail
+
+template <class Allocator = std::allocator<uint64_t>>
+class basic_bigint : protected detail::basic_bigint_base<Allocator>
+{
+    using base_t = detail::basic_bigint_base<Allocator>;
+
+public:
+
+    using size_type = typename base_t::size_type;
+    using value_type = typename base_t::value_type;
+    using base_t::get_allocator;
+    using bigint_type = basic_bigint<Allocator>;
+
+    static constexpr uint64_t max_basic_type = (std::numeric_limits<uint64_t>::max)();
+    static constexpr uint64_t basic_type_bits = sizeof(uint64_t) * 8;  // Number of bits
+    static constexpr uint64_t basic_type_halfBits = basic_type_bits/2;
+
+    static constexpr uint16_t word_length = 4; // Use multiples of word_length words
+    static constexpr uint64_t r_mask = (uint64_t(1) << basic_type_halfBits) - 1;
+    static constexpr uint64_t l_mask = max_basic_type - r_mask;
+    static constexpr uint64_t l_bit = max_basic_type - (max_basic_type >> 1);
+
+private:
+
+    struct common_storage
+    {
+        uint8_t is_dynamic_:1; 
+        uint8_t is_negative_:1; 
+        size_type length_;
+    };
+
+    struct short_storage
+    {
+        uint8_t is_dynamic_:1; 
+        uint8_t is_negative_:1; 
+        size_type length_;
+        uint64_t values_[2];
+
+        short_storage()
+            : is_dynamic_(false), 
+              is_negative_(false),
+              length_(0),
+              values_{0,0}
+        {
+        }
+
+        template <class T>
+        short_storage(T n, 
+                      typename std::enable_if<std::is_integral<T>::value &&
+                                              sizeof(T) <= sizeof(int64_t) &&
+                                              std::is_signed<T>::value>::type* = 0)
+            : is_dynamic_(false), 
+              is_negative_(n < 0),
+              length_(n == 0 ? 0 : 1)
+        {
+            values_[0] = n < 0 ? (uint64_t(0)-static_cast<uint64_t>(n)) : static_cast<uint64_t>(n);
+            values_[1] = 0;
+        }
+
+        template <class T>
+        short_storage(T n, 
+                      typename std::enable_if<std::is_integral<T>::value &&
+                                              sizeof(T) <= sizeof(int64_t) &&
+                                              !std::is_signed<T>::value>::type* = 0)
+            : is_dynamic_(false), 
+              is_negative_(false),
+              length_(n == 0 ? 0 : 1)
+        {
+            values_[0] = n;
+            values_[1] = 0;
+        }
+
+        template <class T>
+        short_storage(T n, 
+                      typename std::enable_if<std::is_integral<T>::value &&
+                                              sizeof(int64_t) < sizeof(T) &&
+                                              std::is_signed<T>::value>::type* = 0)
+            : is_dynamic_(false), 
+              is_negative_(n < 0),
+              length_(n == 0 ? 0 : 2)
+        {
+            using unsigned_type = typename std::make_unsigned<T>::type;
+
+            auto u = n < 0 ? (unsigned_type(0)-static_cast<unsigned_type>(n)) : static_cast<unsigned_type>(n);
+            values_[0] = uint64_t(u & max_basic_type);;
+            u >>= basic_type_bits;
+            values_[1] = uint64_t(u & max_basic_type);;
+        }
+
+        template <class T>
+        short_storage(T n, 
+                      typename std::enable_if<std::is_integral<T>::value &&
+                                              sizeof(int64_t) < sizeof(T) &&
+                                              !std::is_signed<T>::value>::type* = 0)
+            : is_dynamic_(false), 
+              is_negative_(false),
+              length_(n == 0 ? 0 : 2)
+        {
+            values_[0] = uint64_t(n & max_basic_type);;
+            n >>= basic_type_bits;
+            values_[1] = uint64_t(n & max_basic_type);;
+        }
+
+        short_storage(const short_storage& stor)
+            : is_dynamic_(false), 
+              is_negative_(stor.is_negative_),
+              length_(stor.length_)
+        {
+            values_[0] = stor.values_[0];
+            values_[1] = stor.values_[1];
+        }
+
+        short_storage& operator=(const short_storage& stor) = delete;
+    };
+
+    struct dynamic_storage
+    {
+        using real_allocator_type = typename std::allocator_traits<Allocator>:: template rebind_alloc<uint64_t>;
+        using pointer = typename std::allocator_traits<real_allocator_type>::pointer;
+
+        uint8_t is_dynamic_:1; 
+        uint8_t is_negative_:1; 
+        size_type length_;
+        size_type capacity_;
+        pointer data_;
+
+        dynamic_storage()
+            : is_dynamic_(true), 
+              is_negative_(false),
+              length_(0),
+              capacity_(0),
+              data_(nullptr)
+        {
+        }
+
+        dynamic_storage(const dynamic_storage& stor, const real_allocator_type& alloc)
+            : is_dynamic_(true), 
+              is_negative_(stor.is_negative_),
+              length_(stor.length_),
+              capacity_(0),
+              data_(nullptr)
+        {
+            create(stor.length_, alloc);
+            std::memcpy(data_, stor.data_, stor.length_*sizeof(uint64_t));
+        }
+
+        dynamic_storage(dynamic_storage&& stor) noexcept
+            : is_dynamic_(true), 
+              is_negative_(stor.is_negative_),
+              length_(stor.length_),
+              capacity_(stor.capacity_),
+              data_(stor.data_)
+        {
+            stor.length_ = 0;
+            stor.capacity_ = 0;
+            stor.data_ = nullptr;
+        }
+
+        void create(size_type length, real_allocator_type alloc)
+        {
+            capacity_ = round_up(length);
+            data_ = std::allocator_traits<real_allocator_type>::allocate(alloc, capacity_);
+            JSONCONS_TRY
+            {
+                std::allocator_traits<real_allocator_type>::construct(alloc, type_traits::to_plain_pointer(data_));
+            }
+            JSONCONS_CATCH(...)
+            {
+                std::allocator_traits<real_allocator_type>::deallocate(alloc, data_, capacity_);
+                JSONCONS_RETHROW;
+            }
+        }
+
+        void destroy(const real_allocator_type& a) noexcept
+        {
+            if (data_ != nullptr)
+            {
+                real_allocator_type alloc(a);
+
+                std::allocator_traits<real_allocator_type>::destroy(alloc, type_traits::to_plain_pointer(data_));
+                std::allocator_traits<real_allocator_type>::deallocate(alloc, data_,capacity_);
+            }
+        }
+
+        void reserve(size_type n, const real_allocator_type& a)
+        {
+            real_allocator_type alloc(a);
+
+            size_type capacity_new = round_up(n);
+            uint64_t* data_old = data_;
+            data_ = std::allocator_traits<real_allocator_type>::allocate(alloc, capacity_new);
+            if (length_ > 0)
+            {
+                std::memcpy( data_, data_old, length_*sizeof(uint64_t));
+            }
+            if (capacity_ > 0 && data_ != nullptr)
+            {
+                std::allocator_traits<real_allocator_type>::deallocate(alloc, data_old, capacity_);
+            }
+            capacity_ = capacity_new;
+        }
+
+        // Find suitable new block size
+        constexpr size_type round_up(size_type i) const 
+        {
+            return (i/word_length + 1) * word_length;
+        }
+    };
+
+    union
+    {
+        common_storage common_stor_;
+        short_storage short_stor_;
+        dynamic_storage dynamic_stor_;
+    };
+
+public:
+    basic_bigint()
+    {
+        ::new (&short_stor_) short_storage();
+    }
+
+    explicit basic_bigint(const Allocator& alloc)
+        : base_t(alloc)
+    {
+        ::new (&short_stor_) short_storage();
+    }
+
+
+    basic_bigint(const basic_bigint<Allocator>& n)
+        : base_t(n.get_allocator())
+    {
+        if (!n.is_dynamic())
+        {
+            ::new (&short_stor_) short_storage(n.short_stor_);
+        }
+        else
+        {
+            ::new (&dynamic_stor_) dynamic_storage(n.dynamic_stor_, get_allocator());
+        }
+    }
+
+    basic_bigint(basic_bigint<Allocator>&& other) noexcept
+        : base_t(other.get_allocator())
+    {
+        if (!other.is_dynamic())
+        {
+            ::new (&short_stor_) short_storage(other.short_stor_);
+        }
+        else
+        {
+            ::new (&dynamic_stor_) dynamic_storage(std::move(other.dynamic_stor_));
+        }
+    }
+
+    template <class Integer>
+    basic_bigint(Integer n, 
+                 typename std::enable_if<std::is_integral<Integer>::value>::type* = 0)
+    {
+        ::new (&short_stor_) short_storage(n);
+    }
+
+    ~basic_bigint() noexcept
+    {
+        destroy();
+    }
+
+    constexpr bool is_dynamic() const
+    {
+        return common_stor_.is_dynamic_;
+    }
+
+    constexpr size_type length() const
+    {
+        return common_stor_.length_;
+    }
+
+    constexpr size_type capacity() const
+    {
+        return is_dynamic() ? dynamic_stor_.capacity_ : 2;
+    }
+
+    bool is_negative() const
+    {
+        return common_stor_.is_negative_;
+    }
+
+    void is_negative(bool value) 
+    {
+        common_stor_.is_negative_ = value;
+    }
+
+    constexpr const uint64_t* data() const
+    {
+        return is_dynamic() ? dynamic_stor_.data_ : short_stor_.values_;
+    }
+
+    uint64_t* data() 
+    {
+        return is_dynamic() ? dynamic_stor_.data_ : short_stor_.values_;
+    }
+
+    template <class CharT>
+    static basic_bigint<Allocator> from_string(const std::basic_string<CharT>& s)
+    {
+        return from_string(s.data(), s.length());
+    }
+
+    template <class CharT>
+    static basic_bigint<Allocator> from_string(const CharT* s)
+    {
+        return from_string(s, std::char_traits<CharT>::length(s));
+    }
+
+    template <class CharT>
+    static basic_bigint<Allocator> from_string(const CharT* data, size_type length)
+    {
+        bool neg;
+        if (*data == '-')
+        {
+            neg = true;
+            data++;
+            --length;
+        }
+        else
+        {
+            neg = false;
+        }
+
+        basic_bigint<Allocator> v = 0;
+        for (size_type i = 0; i < length; i++)
+        {
+            CharT c = data[i];
+            switch (c)
+            {
+                case '0':case '1':case '2':case '3':case '4':case '5':case '6':case '7':case '8': case '9':
+                    v = (v * 10) + (uint64_t)(c - '0');
+                    break;
+                default:
+                    JSONCONS_THROW(std::runtime_error(std::string("Invalid digit ") + "\'" + (char)c + "\'"));
+            }
+        }
+
+        if (neg)
+        {
+            v.common_stor_.is_negative_ = true;
+        }
+
+        return v;
+    }
+
+    template <class CharT>
+    static basic_bigint<Allocator> from_string_radix(const CharT* data, size_type length, uint8_t radix)
+    {
+        if (!(radix >= 2 && radix <= 16))
+        {
+            JSONCONS_THROW(std::runtime_error("Unsupported radix"));
+        }
+
+        bool neg;
+        if (*data == '-')
+        {
+            neg = true;
+            data++;
+            --length;
+        }
+        else
+        {
+            neg = false;
+        }
+
+        basic_bigint<Allocator> v = 0;
+        for (size_type i = 0; i < length; i++)
+        {
+            CharT c = data[i];
+            uint64_t d;
+            switch (c)
+            {
+                case '0':case '1':case '2':case '3':case '4':case '5':case '6':case '7':case '8': case '9':
+                    d = (uint64_t)(c - '0');
+                    break;
+                case 'a':case 'b':case 'c':case 'd':case 'e':case 'f':
+                    d = (uint64_t)(c - ('a' - 10));
+                    break;
+                case 'A':case 'B':case 'C':case 'D':case 'E':case 'F':
+                    d = (uint64_t)(c - ('A' - 10));
+                    break;
+                default:
+                    JSONCONS_THROW(std::runtime_error(std::string("Invalid digit in radix ") + std::to_string(radix) + ": \'" + (char)c + "\'"));
+            }
+            if (d >= radix)
+            {
+                JSONCONS_THROW(std::runtime_error(std::string("Invalid digit in radix ") + std::to_string(radix) + ": \'" + (char)c + "\'"));
+            }
+            v = (v * radix) + d;
+        }
+
+        if ( neg )
+        {
+            v.common_stor_.is_negative_ = true;
+        }
+        return v;
+    }
+
+    static basic_bigint from_bytes_be(int signum, const uint8_t* str, std::size_t n)
+    {
+        static const double radix_log2 = std::log2(next_power_of_two(256));
+        // Estimate how big the result will be, so we can pre-allocate it.
+        double bits = radix_log2 * n;
+        double big_digits = std::ceil(bits / 64.0);
+        //std::cout << "ESTIMATED: " << big_digits << "\n";
+
+        bigint_type v = 0;
+        v.reserve(static_cast<std::size_t>(big_digits));
+
+        if (n > 0)
+        {
+            for (std::size_t i = 0; i < n; i++)
+            {
+                v = (v * 256) + (uint64_t)(str[i]);
+            }
+        }
+        //std::cout << "ACTUAL: " << v.length() << "\n";
+
+        if (signum < 0)
+        {
+            v.common_stor_.is_negative_ = true;
+        }
+
+        return v;
+    }
+
+    uint64_t* begin() { return is_dynamic() ? dynamic_stor_.data_ : short_stor_.values_; }
+    const uint64_t* begin() const { return is_dynamic() ? dynamic_stor_.data_ : short_stor_.values_; }
+    uint64_t* end() { return begin() + length(); }
+    const uint64_t* end() const { return begin() + length(); }
+
+    void resize(size_type n)
+    {
+        size_type len_old = common_stor_.length_;
+        reserve(n);
+        common_stor_.length_ = n;
+        if ( common_stor_.length_ > len_old )
+        {
+            memset( data()+len_old, 0, (common_stor_.length_ - len_old)*sizeof(uint64_t) );
+        }
+    }
+
+    void reserve(size_type n)
+    {
+       if (capacity() < n)
+       {
+           if (!is_dynamic())
+           {
+               size_type size = short_stor_.length_;
+               size_type is_neg = short_stor_.is_negative_;
+               uint64_t values[2] = {short_stor_.values_[0], short_stor_.values_[1]};
+
+               ::new (&dynamic_stor_) dynamic_storage();
+               dynamic_stor_.reserve(n, get_allocator());
+               dynamic_stor_.length_ = size;
+               dynamic_stor_.is_negative_ = is_neg;
+               dynamic_stor_.data_[0] = values[0];
+               dynamic_stor_.data_[1] = values[1];
+           }
+           else
+           {
+               dynamic_stor_.reserve(n, get_allocator());
+           }
+       }
+    }
+
+    // operators
+
+    bool operator!() const
+    {
+        return length() == 0 ? true : false;
+    }
+
+    basic_bigint operator-() const
+    {
+        basic_bigint<Allocator> v(*this);
+        v.common_stor_.is_negative_ = !v.is_negative();
+        return v;
+    }
+
+    basic_bigint& operator=( const basic_bigint<Allocator>& y )
+    {
+        if ( this != &y )
+        {
+            resize( y.length() );
+            common_stor_.is_negative_ = y.is_negative();
+            if ( y.length() > 0 )
+            {
+                std::memcpy( data(), y.data(), y.length()*sizeof(uint64_t) );
+            }
+        }
+        return *this;
+    }
+
+    basic_bigint& operator+=( const basic_bigint<Allocator>& y )
+    {
+        if ( is_negative() != y.is_negative() )
+            return *this -= -y;
+        uint64_t d;
+        uint64_t carry = 0;
+
+        resize( (std::max)(y.length(), length()) + 1 );
+
+        for (size_type i = 0; i < length(); i++ )
+        {
+            if ( i >= y.length() && carry == 0 )
+                break;
+            d = data()[i] + carry;
+            carry = d < carry;
+            if ( i < y.length() )
+            {
+                data()[i] = d + y.data()[i];
+                if ( data()[i] < d )
+                    carry = 1;
+            }
+            else
+                data()[i] = d;
+        }
+        reduce();
+        return *this;
+    }
+
+    basic_bigint& operator-=( const basic_bigint<Allocator>& y )
+    {
+        if ( is_negative() != y.is_negative() )
+            return *this += -y;
+        if ( (!is_negative() && y > *this) || (is_negative() && y < *this) )
+            return *this = -(y - *this);
+        uint64_t borrow = 0;
+        uint64_t d;
+        for (size_type i = 0; i < length(); i++ )
+        {
+            if ( i >= y.length() && borrow == 0 )
+                break;
+            d = data()[i] - borrow;
+            borrow = d > data()[i];
+            if ( i < y.length())
+            {
+                data()[i] = d - y.data()[i];
+                if ( data()[i] > d )
+                    borrow = 1;
+            }
+            else 
+                data()[i] = d;
+        }
+        reduce();
+        return *this;
+    }
+
+    basic_bigint& operator*=( int64_t y )
+    {
+        *this *= uint64_t(y < 0 ? -y : y);
+        if ( y < 0 )
+            common_stor_.is_negative_ = !is_negative();
+        return *this;
+    }
+
+    basic_bigint& operator*=( uint64_t y )
+    {
+        size_type len0 = length();
+        uint64_t hi;
+        uint64_t lo;
+        uint64_t dig = data()[0];
+        uint64_t carry = 0;
+
+        resize( length() + 1 );
+
+        size_type i = 0;
+        for (i = 0; i < len0; i++ )
+        {
+            DDproduct( dig, y, hi, lo );
+            data()[i] = lo + carry;
+            dig = data()[i+1];
+            carry = hi + (data()[i] < lo);
+        }
+        data()[i] = carry;
+        reduce();
+        return *this;
+    }
+
+    basic_bigint& operator*=( basic_bigint<Allocator> y )
+    {
+        if ( length() == 0 || y.length() == 0 )
+                    return *this = 0;
+        bool difSigns = is_negative() != y.is_negative();
+        if ( length() + y.length() == 2 ) // length() = y.length() = 1
+        {
+            uint64_t a = data()[0], b = y.data()[0];
+            data()[0] = a * b;
+            if ( data()[0] / a != b )
+            {
+                resize( 2 );
+                DDproduct( a, b, data()[1], data()[0] );
+            }
+            common_stor_.is_negative_ = difSigns;
+            return *this;
+        }
+        if ( length() == 1 )  //  && y.length() > 1
+        {
+            uint64_t digit = data()[0];
+            *this = y;
+            *this *= digit;
+        }
+        else
+        {
+            if ( y.length() == 1 )
+                *this *= y.data()[0];
+            else
+            {
+                size_type lenProd = length() + y.length(), jA, jB;
+                uint64_t sumHi = 0, sumLo, hi, lo,
+                sumLo_old, sumHi_old, carry=0;
+                basic_bigint<Allocator> x = *this;
+                resize( lenProd ); // Give *this length lenProd
+
+                for (size_type i = 0; i < lenProd; i++ )
+                {
+                    sumLo = sumHi;
+                    sumHi = carry;
+                    carry = 0;
+                    for ( jA=0; jA < x.length(); jA++ )
+                    {
+                        jB = i - jA;
+                        if ( jB >= 0 && jB < y.length() )
+                        {
+                            DDproduct( x.data()[jA], y.data()[jB], hi, lo );
+                            sumLo_old = sumLo;
+                            sumHi_old = sumHi;
+                            sumLo += lo;
+                            if ( sumLo < sumLo_old )
+                                sumHi++;
+                            sumHi += hi;
+                            carry += (sumHi < sumHi_old);
+                        }
+                    }
+                    data()[i] = sumLo;
+                }
+            }
+        }
+       reduce();
+       common_stor_.is_negative_ = difSigns;
+       return *this;
+    }
+
+    basic_bigint& operator/=( const basic_bigint<Allocator>& divisor )
+    {
+        basic_bigint<Allocator> r;
+        divide( divisor, *this, r, false );
+        return *this;
+    }
+
+    basic_bigint& operator%=( const basic_bigint<Allocator>& divisor )
+    {
+        basic_bigint<Allocator> q;
+        divide( divisor, q, *this, true );
+        return *this;
+    }
+
+    basic_bigint& operator<<=( uint64_t k )
+    {
+        size_type q = (size_type)(k / basic_type_bits);
+        if ( q ) // Increase common_stor_.length_ by q:
+        {
+            resize(length() + q);
+            for (size_type i = length(); i-- > 0; )
+                data()[i] = ( i < q ? 0 : data()[i - q]);
+            k %= basic_type_bits;
+        }
+        if ( k )  // 0 < k < basic_type_bits:
+        {
+            uint64_t k1 = basic_type_bits - k;
+            uint64_t mask = (uint64_t(1) << k) - uint64_t(1);
+            resize( length() + 1 );
+            for (size_type i = length(); i-- > 0; )
+            {
+                data()[i] <<= k;
+                if ( i > 0 )
+                    data()[i] |= (data()[i-1] >> k1) & mask;
+            }
+        }
+        reduce();
+        return *this;
+    }
+
+    basic_bigint& operator>>=(uint64_t k)
+    {
+        size_type q = (size_type)(k / basic_type_bits);
+        if ( q >= length() )
+        {
+            resize( 0 );
+            return *this;
+        }
+        if (q > 0)
+        {
+            memmove( data(), data()+q, (size_type)((length() - q)*sizeof(uint64_t)) );
+            resize( length() - q );
+            k %= basic_type_bits;
+            if ( k == 0 )
+            {
+                reduce();
+                return *this;
+            }
+        }
+
+        size_type n = (size_type)(length() - 1);
+        int64_t k1 = basic_type_bits - k;
+        uint64_t mask = (uint64_t(1) << k) - 1;
+        for (size_type i = 0; i <= n; i++)
+        {
+            data()[i] >>= k;
+            if ( i < n )
+                data()[i] |= ((data()[i+1] & mask) << k1);
+        }
+        reduce();
+        return *this;
+    }
+
+    basic_bigint& operator++()
+    {
+        *this += 1;
+        return *this;
+    }
+
+    basic_bigint<Allocator> operator++(int)
+    {
+        basic_bigint<Allocator> old = *this;
+        ++(*this);
+        return old;
+    }
+
+    basic_bigint<Allocator>& operator--()
+    {
+        *this -= 1;
+        return *this;
+    }
+
+    basic_bigint<Allocator> operator--(int)
+    {
+        basic_bigint<Allocator> old = *this;
+        --(*this);
+        return old;
+    }
+
+    basic_bigint& operator|=( const basic_bigint<Allocator>& a )
+    {
+        if ( length() < a.length() )
+        {
+            resize( a.length() );
+        }
+
+        const uint64_t* qBegin = a.begin();
+        const uint64_t* q =      a.end() - 1;
+        uint64_t*       p =      begin() + a.length() - 1;
+
+        while ( q >= qBegin )
+        {
+            *p-- |= *q--;
+        }
+
+        reduce();
+
+        return *this;
+    }
+
+    basic_bigint& operator^=( const basic_bigint<Allocator>& a )
+    {
+        if ( length() < a.length() )
+        {
+            resize( a.length() );
+        }
+
+        const uint64_t* qBegin = a.begin();
+        const uint64_t* q = a.end() - 1;
+        uint64_t* p = begin() + a.length() - 1;
+
+        while ( q >= qBegin )
+        {
+            *p-- ^= *q--;
+        }
+
+        reduce();
+
+        return *this;
+    }
+
+    basic_bigint& operator&=( const basic_bigint<Allocator>& a )
+    {
+        size_type old_length = length();
+
+        resize( (std::min)( length(), a.length() ) );
+
+        const uint64_t* pBegin = begin();
+        uint64_t* p = end() - 1;
+        const uint64_t* q = a.begin() + length() - 1;
+
+        while ( p >= pBegin )
+        {
+            *p-- &= *q--;
+        }
+
+        if ( old_length > length() )
+        {
+            memset( data() + length(), 0, old_length - length() );
+        }
+
+        reduce();
+
+        return *this;
+    }
+
+    explicit operator bool() const
+    {
+       return length() != 0 ? true : false;
+    }
+
+    explicit operator int64_t() const
+    {
+       int64_t x = 0;
+       if ( length() > 0 )
+       {
+           x = data() [0];
+       }
+
+       return is_negative() ? -x : x;
+    }
+
+    explicit operator uint64_t() const
+    {
+       uint64_t u = 0;
+       if ( length() > 0 )
+       {
+           u = data() [0];
+       }
+
+       return u;
+    }
+
+    explicit operator double() const
+    {
+        double x = 0.0;
+        double factor = 1.0;
+        double values = (double)max_basic_type + 1.0;
+
+        const uint64_t* p = begin();
+        const uint64_t* pEnd = end();
+        while ( p < pEnd )
+        {
+            x += *p*factor;
+            factor *= values;
+            ++p;
+        }
+
+       return is_negative() ? -x : x;
+    }
+
+    explicit operator long double() const
+    {
+        long double x = 0.0;
+        long double factor = 1.0;
+        long double values = (long double)max_basic_type + 1.0;
+
+        const uint64_t* p = begin();
+        const uint64_t* pEnd = end();
+        while ( p < pEnd )
+        {
+            x += *p*factor;
+            factor *= values;
+            ++p;
+        }
+
+       return is_negative() ? -x : x;
+    }
+
+    template <typename Alloc>
+    void write_bytes_be(int& signum, std::vector<uint8_t,Alloc>& data) const
+    {
+        basic_bigint<Allocator> n(*this);
+        signum = (n < 0) ? -1 : (n > 0 ? 1 : 0); 
+
+        basic_bigint<Allocator> divisor(256);
+
+        while (n >= 256)
+        {
+            basic_bigint<Allocator> q;
+            basic_bigint<Allocator> r;
+            n.divide(divisor, q, r, true);
+            n = q;
+            data.push_back((uint8_t)(uint64_t)r);
+        }
+        if (n >= 0)
+        {
+            data.push_back((uint8_t)(uint64_t)n);
+        }
+        std::reverse(data.begin(),data.end());
+    }
+
+    std::string to_string() const
+    {
+        std::string s;
+        write_string(s);
+        return s;
+    }
+
+    template <typename Ch, typename Traits, typename Alloc>
+    void write_string(std::basic_string<Ch,Traits,Alloc>& data) const
+    {
+        basic_bigint<Allocator> v(*this);
+
+        size_t len = (v.length() * basic_type_bits / 3) + 2;
+        data.reserve(len);
+
+        static uint64_t p10 = 1;
+        static uint64_t ip10 = 0;
+
+        if ( v.length() == 0 )
+        {
+            data.push_back('0');
+        }
+        else
+        {
+            uint64_t r;
+            if ( p10 == 1 )
+            {
+                while ( p10 <= (std::numeric_limits<uint64_t>::max)()/10 )
+                {
+                    p10 *= 10;
+                    ip10++;
+                }
+            }                     
+            // p10 is max unsigned power of 10
+            basic_bigint<Allocator> R;
+            basic_bigint<Allocator> LP10 = p10; // LP10 = p10 = ::pow(10, ip10)
+
+            do
+            {
+                v.divide( LP10, v, R, true );
+                r = (R.length() ? R.data()[0] : 0);
+                for ( size_type j=0; j < ip10; j++ )
+                {
+                    data.push_back(char(r % 10 + '0'));
+                    r /= 10;
+                    if ( r + v.length() == 0 )
+                        break;
+                }
+            } 
+            while ( v.length() );
+            if (is_negative())
+            {
+                data.push_back('-');
+            }
+            std::reverse(data.begin(),data.end());
+        }
+    }
+
+    std::string to_string_hex() const
+    {
+        std::string s;
+        write_string_hex(s);
+        return s;
+    }
+
+    template <typename Ch, typename Traits, typename Alloc>
+    void write_string_hex(std::basic_string<Ch,Traits,Alloc>& data) const
+    {
+        basic_bigint<Allocator> v(*this);
+
+        std::size_t len = (v.length() * basic_bigint<Allocator>::basic_type_bits / 3) + 2;
+        data.reserve(len);
+        // 1/3 > ln(2)/ln(10)
+        static uint64_t p10 = 1;
+        static uint64_t ip10 = 0;
+
+        if ( v.length() == 0 )
+        {
+            data.push_back('0');
+        }
+        else
+        {
+            uint64_t r;
+            if ( p10 == 1 )
+            {
+                while ( p10 <= (std::numeric_limits<uint64_t>::max)()/16 )
+                {
+                    p10 *= 16;
+                    ip10++;
+                }
+            }                     // p10 is max unsigned power of 16
+            basic_bigint<Allocator> R;
+            basic_bigint<Allocator> LP10 = p10; // LP10 = p10 = ::pow(16, ip10)
+            do
+            {
+                v.divide( LP10, v, R, true );
+                r = (R.length() ? R.data()[0] : 0);
+                for ( size_type j=0; j < ip10; j++ )
+                {
+                    uint8_t c = r % 16;
+                    data.push_back((c < 10) ? ('0' + c) : ('A' - 10 + c));
+                    r /= 16;
+                    if ( r + v.length() == 0 )
+                        break;
+                }
+            } 
+            while (v.length());
+
+            if (is_negative())
+            {
+                data.push_back('-');
+            }
+            std::reverse(data.begin(),data.end());
+        }
+    }
+
+//  Global Operators
+
+    friend bool operator==( const basic_bigint<Allocator>& x, const basic_bigint<Allocator>& y ) noexcept
+    {
+        return x.compare(y) == 0 ? true : false;
+    }
+
+    friend bool operator==( const basic_bigint<Allocator>& x, int y ) noexcept
+    {
+        return x.compare(y) == 0 ? true : false;
+    }
+
+    friend bool operator!=( const basic_bigint<Allocator>& x, const basic_bigint<Allocator>& y ) noexcept
+    {
+        return x.compare(y) != 0 ? true : false;
+    }
+
+    friend bool operator!=( const basic_bigint<Allocator>& x, int y ) noexcept
+    {
+        return x.compare(basic_bigint<Allocator>(y)) != 0 ? true : false;
+    }
+
+    friend bool operator<( const basic_bigint<Allocator>& x, const basic_bigint<Allocator>& y ) noexcept
+    {
+       return x.compare(y) < 0 ? true : false;
+    }
+
+    friend bool operator<( const basic_bigint<Allocator>& x, int64_t y ) noexcept
+    {
+       return x.compare(y) < 0 ? true : false;
+    }
+
+    friend bool operator>( const basic_bigint<Allocator>& x, const basic_bigint<Allocator>& y ) noexcept
+    {
+        return x.compare(y) > 0 ? true : false;
+    }
+
+    friend bool operator>( const basic_bigint<Allocator>& x, int y ) noexcept
+    {
+        return x.compare(basic_bigint<Allocator>(y)) > 0 ? true : false;
+    }
+
+    friend bool operator<=( const basic_bigint<Allocator>& x, const basic_bigint<Allocator>& y ) noexcept
+    {
+        return x.compare(y) <= 0 ? true : false;
+    }
+
+    friend bool operator<=( const basic_bigint<Allocator>& x, int y ) noexcept
+    {
+        return x.compare(y) <= 0 ? true : false;
+    }
+
+    friend bool operator>=( const basic_bigint<Allocator>& x, const basic_bigint<Allocator>& y ) noexcept
+    {
+        return x.compare(y) >= 0 ? true : false;
+    }
+
+    friend bool operator>=( const basic_bigint<Allocator>& x, int y ) noexcept
+    {
+        return x.compare(y) >= 0 ? true : false;
+    }
+
+    friend basic_bigint<Allocator> operator+( basic_bigint<Allocator> x, const basic_bigint<Allocator>& y )
+    {
+        return x += y;
+    }
+
+    friend basic_bigint<Allocator> operator+( basic_bigint<Allocator> x, int64_t y )
+    {
+        return x += y;
+    }
+
+    friend basic_bigint<Allocator> operator-( basic_bigint<Allocator> x, const basic_bigint<Allocator>& y )
+    {
+        return x -= y;
+    }
+
+    friend basic_bigint<Allocator> operator-( basic_bigint<Allocator> x, int64_t y )
+    {
+        return x -= y;
+    }
+
+    friend basic_bigint<Allocator> operator*( int64_t x, const basic_bigint<Allocator>& y )
+    {
+        return basic_bigint<Allocator>(y) *= x;
+    }
+
+    friend basic_bigint<Allocator> operator*( basic_bigint<Allocator> x, const basic_bigint<Allocator>& y )
+    {
+        return x *= y;
+    }
+
+    friend basic_bigint<Allocator> operator*( basic_bigint<Allocator> x, int64_t y )
+    {
+        return x *= y;
+    }
+
+    friend basic_bigint<Allocator> operator/( basic_bigint<Allocator> x, const basic_bigint<Allocator>& y )
+    {
+        return x /= y;
+    }
+
+    friend basic_bigint<Allocator> operator/( basic_bigint<Allocator> x, int y )
+    {
+        return x /= y;
+    }
+
+    friend basic_bigint<Allocator> operator%( basic_bigint<Allocator> x, const basic_bigint<Allocator>& y )
+    {
+        return x %= y;
+    }
+
+    friend basic_bigint<Allocator> operator<<( basic_bigint<Allocator> u, unsigned k )
+    {
+        return u <<= k;
+    }
+
+    friend basic_bigint<Allocator> operator<<( basic_bigint<Allocator> u, int k )
+    {
+        return u <<= k;
+    }
+
+    friend basic_bigint<Allocator> operator>>( basic_bigint<Allocator> u, unsigned k )
+    {
+        return u >>= k;
+    }
+
+    friend basic_bigint<Allocator> operator>>( basic_bigint<Allocator> u, int k )
+    {
+        return u >>= k;
+    }
+
+    friend basic_bigint<Allocator> operator|( basic_bigint<Allocator> x, const basic_bigint<Allocator>& y )
+    {
+        return x |= y;
+    }
+
+    friend basic_bigint<Allocator> operator|( basic_bigint<Allocator> x, int y )
+    {
+        return x |= y;
+    }
+
+    friend basic_bigint<Allocator> operator|( basic_bigint<Allocator> x, unsigned y )
+    {
+        return x |= y;
+    }
+
+    friend basic_bigint<Allocator> operator^( basic_bigint<Allocator> x, const basic_bigint<Allocator>& y )
+    {
+        return x ^= y;
+    }
+
+    friend basic_bigint<Allocator> operator^( basic_bigint<Allocator> x, int y )
+    {
+        return x ^= y;
+    }
+
+    friend basic_bigint<Allocator> operator^( basic_bigint<Allocator> x, unsigned y )
+    {
+        return x ^= y;
+    }
+
+    friend basic_bigint<Allocator> operator&( basic_bigint<Allocator> x, const basic_bigint<Allocator>& y )
+    {
+        return x &= y;
+    }
+
+    friend basic_bigint<Allocator> operator&( basic_bigint<Allocator> x, int y )
+    {
+        return x &= y;
+    }
+
+    friend basic_bigint<Allocator> operator&( basic_bigint<Allocator> x, unsigned y )
+    {
+        return x &= y;
+    }
+
+    friend basic_bigint<Allocator> abs( const basic_bigint<Allocator>& a )
+    {
+        if ( a.is_negative() )
+        {
+            return -a;
+        }
+        return a;
+    }
+
+    friend basic_bigint<Allocator> power( basic_bigint<Allocator> x, unsigned n )
+    {
+        basic_bigint<Allocator> y = 1;
+
+        while ( n )
+        {
+            if ( n & 1 )
+            {
+                y *= x;
+            }
+            x *= x;
+            n >>= 1;
+        }
+
+        return y;
+    }
+
+    friend basic_bigint<Allocator> sqrt( const basic_bigint<Allocator>& a )
+    {
+        basic_bigint<Allocator> x = a;
+        basic_bigint<Allocator> b = a;
+        basic_bigint<Allocator> q;
+
+        b <<= 1;
+        while ( b >>= 2, b > 0 )
+        {
+            x >>= 1;
+        }
+        while ( x > (q = a/x) + 1 || x < q - 1 )
+        {
+            x += q;
+            x >>= 1;
+        }
+        return x < q ? x : q;
+    }
+
+    template <class CharT>
+    friend std::basic_ostream<CharT>& operator<<(std::basic_ostream<CharT>& os, const basic_bigint<Allocator>& v)
+    {
+        std::basic_string<CharT> s;
+        v.write_string(s); 
+        os << s;
+
+        return os;
+    }
+
+    int compare( const basic_bigint<Allocator>& y ) const noexcept
+    {
+        if ( is_negative() != y.is_negative() )
+            return y.is_negative() - is_negative();
+        int code = 0;
+        if ( length() == 0 && y.length() == 0 )
+            code = 0;
+        else if ( length() < y.length() )
+            code = -1;
+        else if ( length() > y.length() )
+            code = +1;
+        else
+        {
+            for (size_type i = length(); i-- > 0; )
+            {
+                if (data()[i] > y.data()[i])
+                {
+                    code = 1;
+                    break;
+                }
+                else if (data()[i] < y.data()[i])
+                {
+                    code = -1;
+                    break;
+                }
+            }
+        }
+        return is_negative() ? -code : code;
+    }
+
+    void divide( basic_bigint<Allocator> denom, basic_bigint<Allocator>& quot, basic_bigint<Allocator>& rem, bool remDesired ) const
+    {
+        if ( denom.length() == 0 )
+        {
+            JSONCONS_THROW(std::runtime_error( "Zero divide." ));
+        }
+        bool quot_neg = is_negative() ^ denom.is_negative();
+        bool rem_neg = is_negative();
+        int x = 0;
+        basic_bigint<Allocator> num = *this;
+        num.common_stor_.is_negative_ = denom.common_stor_.is_negative_ = false;
+        if ( num < denom )
+        {
+            quot = uint64_t(0);
+            rem = num;
+            rem.common_stor_.is_negative_ = rem_neg;
+            return;
+        }
+        if ( denom.length() == 1 && num.length() == 1 )
+        {
+            quot = uint64_t( num.data()[0]/denom.data()[0] );
+            rem = uint64_t( num.data()[0]%denom.data()[0] );
+            quot.common_stor_.is_negative_ = quot_neg;
+            rem.common_stor_.is_negative_ = rem_neg;
+            return;
+        }
+        else if (denom.length() == 1 && (denom.data()[0] & l_mask) == 0 )
+        {
+            // Denominator fits into a half word
+            uint64_t divisor = denom.data()[0], dHi = 0,
+                     q1, r, q2, dividend;
+            quot.resize(length());
+            for (size_type i=length(); i-- > 0; )
+            {
+                dividend = (dHi << basic_type_halfBits) | (data()[i] >> basic_type_halfBits);
+                q1 = dividend/divisor;
+                r = dividend % divisor;
+                dividend = (r << basic_type_halfBits) | (data()[i] & r_mask);
+                q2 = dividend/divisor;
+                dHi = dividend % divisor;
+                quot.data()[i] = (q1 << basic_type_halfBits) | q2;
+            }
+            quot.reduce();
+            rem = dHi;
+            quot.common_stor_.is_negative_ = quot_neg;
+            rem.common_stor_.is_negative_ = rem_neg;
+            return;
+        }
+        basic_bigint<Allocator> num0 = num, denom0 = denom;
+        int second_done = normalize(denom, num, x);
+        size_type l = denom.length() - 1;
+        size_type n = num.length() - 1;
+        quot.resize(n - l);
+        for (size_type i=quot.length(); i-- > 0; )
+            quot.data()[i] = 0;
+        rem = num;
+        if ( rem.data()[n] >= denom.data()[l] )
+        {
+            rem.resize(rem.length() + 1);
+            n++;
+            quot.resize(quot.length() + 1);
+        }
+        uint64_t d = denom.data()[l];
+        for ( size_type k = n; k > l; k-- )
+        {
+            uint64_t q = DDquotient(rem.data()[k], rem.data()[k-1], d);
+            subtractmul( rem.data() + k - l - 1, denom.data(), l + 1, q );
+            quot.data()[k - l - 1] = q;
+        }
+        quot.reduce();
+        quot.common_stor_.is_negative_ = quot_neg;
+        if ( remDesired )
+        {
+            unnormalize(rem, x, second_done);
+            rem.common_stor_.is_negative_ = rem_neg;
+        }
+    }
+private:
+    void destroy() noexcept
+    {
+        if (is_dynamic())
+        {
+            dynamic_stor_.destroy(get_allocator());
+        }
+    }
+    void DDproduct( uint64_t A, uint64_t B,
+                    uint64_t& hi, uint64_t& lo ) const
+    // Multiplying two digits: (hi, lo) = A * B
+    {
+        uint64_t hiA = A >> basic_type_halfBits, loA = A & r_mask,
+                   hiB = B >> basic_type_halfBits, loB = B & r_mask,
+                   mid1, mid2, old;
+
+        lo = loA * loB;
+        hi = hiA * hiB;
+        mid1 = loA * hiB;
+        mid2 = hiA * loB;
+        old = lo;
+        lo += mid1 << basic_type_halfBits;
+            hi += (lo < old) + (mid1 >> basic_type_halfBits);
+        old = lo;
+        lo += mid2 << basic_type_halfBits;
+            hi += (lo < old) + (mid2 >> basic_type_halfBits);
+    }
+
+    uint64_t DDquotient( uint64_t A, uint64_t B, uint64_t d ) const
+    // Divide double word (A, B) by d. Quotient = (qHi, qLo)
+    {
+        uint64_t left, middle, right, qHi, qLo, x, dLo1,
+                   dHi = d >> basic_type_halfBits, dLo = d & r_mask;
+        qHi = A/(dHi + 1);
+        // This initial guess of qHi may be too small.
+        middle = qHi * dLo;
+        left = qHi * dHi;
+        x = B - (middle << basic_type_halfBits);
+        A -= (middle >> basic_type_halfBits) + left + (x > B);
+        B = x;
+        dLo1 = dLo << basic_type_halfBits;
+        // Increase qHi if necessary:
+        while ( A > dHi || (A == dHi && B >= dLo1) )
+        {
+            x = B - dLo1;
+            A -= dHi + (x > B);
+            B = x;
+            qHi++;
+        }
+        qLo = ((A << basic_type_halfBits) | (B >> basic_type_halfBits))/(dHi + 1);
+        // This initial guess of qLo may be too small.
+        right = qLo * dLo;
+        middle = qLo * dHi;
+        x = B - right;
+        A -= (x > B);
+        B = x;
+        x = B - (middle << basic_type_halfBits);
+            A -= (middle >> basic_type_halfBits) + (x > B);
+        B = x;
+        // Increase qLo if necessary:
+        while ( A || B >= d )
+        {
+            x = B - d;
+            A -= (x > B);
+            B = x;
+            qLo++;
+        }
+        return (qHi << basic_type_halfBits) + qLo;
+    }
+
+    void subtractmul( uint64_t* a, uint64_t* b, size_type n, uint64_t& q ) const
+    // a -= q * b: b in n positions; correct q if necessary
+    {
+        uint64_t hi, lo, d, carry = 0;
+        size_type i;
+        for ( i = 0; i < n; i++ )
+        {
+            DDproduct( b[i], q, hi, lo );
+            d = a[i];
+            a[i] -= lo;
+            if ( a[i] > d )
+                carry++;
+            d = a[i + 1];
+            a[i + 1] -= hi + carry;
+            carry = a[i + 1] > d;
+        }
+        if ( carry ) // q was too large
+        {
+            q--;
+            carry = 0;
+            for ( i = 0; i < n; i++ )
+            {
+                d = a[i] + carry;
+                carry = d < carry;
+                a[i] = d + b[i];
+                if ( a[i] < d )
+                    carry = 1;
+            }
+            a[n] = 0;
+        }
+    }
+
+    int normalize( basic_bigint<Allocator>& denom, basic_bigint<Allocator>& num, int& x ) const
+    {
+        size_type r = denom.length() - 1;
+        uint64_t y = denom.data()[r];
+
+        x = 0;
+        while ( (y & l_bit) == 0 )
+        {
+            y <<= 1;
+            x++;
+        }
+        denom <<= x;
+        num <<= x;
+        if ( r > 0 && denom.data()[r] < denom.data()[r-1] )
+        {
+            denom *= max_basic_type;
+                    num *= max_basic_type;
+            return 1;
+        }
+        return 0;
+    }
+
+    void unnormalize( basic_bigint<Allocator>& rem, int x, int secondDone ) const
+    {
+        if ( secondDone )
+        {
+            rem /= max_basic_type;
+        }
+        if ( x > 0 )
+        {
+            rem >>= x;
+        }
+        else
+        {
+            rem.reduce();
+        }
+    }
+
+    size_type round_up(size_type i) const // Find suitable new block size
+    {
+        return (i/word_length + 1) * word_length;
+    }
+
+    void reduce()
+    {
+        uint64_t* p = end() - 1;
+        uint64_t* pBegin = begin();
+        while ( p >= pBegin )
+        {
+            if ( *p )
+            {
+                break;
+            }
+            --common_stor_.length_;
+            --p;
+        }
+        if ( length() == 0 )
+        {
+            common_stor_.is_negative_ = false;
+        }
+    }
+ 
+    static uint64_t next_power_of_two(uint64_t n) {
+        n = n - 1;
+        n |= n >> 1;
+        n |= n >> 2;
+        n |= n >> 4;
+        n |= n >> 8;
+        n |= n >> 16;
+        n |= n >> 32;
+        return n + 1;
+    }
+};
+
+using bigint = basic_bigint<std::allocator<uint8_t>>;
+
+#if !defined(JSONCONS_NO_DEPRECATED)
+JSONCONS_DEPRECATED_MSG("Instead, use bigint") typedef bigint bignum;
+#endif
+
+}
+
+#endif