internal::BigInteger Class Reference

#include <biginteger.h>

Public Types
typedef uint64_t	Type

Public Member Functions
	BigInteger (const BigInteger &rhs)
	BigInteger (uint64_t u)
	BigInteger (const char *decimals, size_t length)
BigInteger &	operator= (const BigInteger &rhs)
BigInteger &	operator= (uint64_t u)
BigInteger &	operator+= (uint64_t u)
BigInteger &	operator*= (uint64_t u)
BigInteger &	operator*= (uint32_t u)
BigInteger &	operator<<= (size_t shift)
bool	operator== (const BigInteger &rhs) const
bool	operator== (const Type rhs) const
BigInteger &	MultiplyPow5 (unsigned exp)
bool	Difference (const BigInteger &rhs, BigInteger *out) const
int	Compare (const BigInteger &rhs) const
size_t	GetCount () const
Type	GetDigit (size_t index) const
bool	IsZero () const

Private Member Functions
void	AppendDecimal64 (const char *begin, const char *end)
void	PushBack (Type digit)

Static Private Member Functions
static uint64_t	ParseUint64 (const char *begin, const char *end)
static uint64_t	MulAdd64 (uint64_t a, uint64_t b, uint64_t k, uint64_t *outHigh)

Private Attributes
Type	digits_ [kCapacity]
size_t	count_

Static Private Attributes
static const size_t	kBitCount = 3328
static const size_t	kCapacity = kBitCount / sizeof(Type)
static const size_t	kTypeBit = sizeof(Type) * 8

Detailed Description

Definition at line 28 of file biginteger.h.

Member Typedef Documentation

typedef uint64_t internal::BigInteger::Type

Definition at line 30 of file biginteger.h.

Constructor & Destructor Documentation

internal::BigInteger::BigInteger ( const BigInteger &  rhs )

inline

Definition at line 32 of file biginteger.h.

                                      : count_(rhs.count_) {
        std::memcpy(digits_, rhs.digits_, count_ * sizeof(Type));
    }

internal::BigInteger::BigInteger ( uint64_t  u )

inlineexplicit

Definition at line 36 of file biginteger.h.

                                    : count_(1) {
        digits_[0] = u;
    }

internal::BigInteger::BigInteger ( const char *  decimals, size_t  length  )

inline

Definition at line 40 of file biginteger.h.

                                                    : count_(1) {
        RAPIDJSON_ASSERT(length > 0);
        digits_[0] = 0;
        size_t i = 0;
        const size_t kMaxDigitPerIteration = 19;  // 2^64 = 18446744073709551616 > 10^19
        while (length >= kMaxDigitPerIteration) {
            AppendDecimal64(decimals + i, decimals + i + kMaxDigitPerIteration);
            length -= kMaxDigitPerIteration;
            i += kMaxDigitPerIteration;
        }

        if (length > 0)
            AppendDecimal64(decimals + i, decimals + i + length);
    }

Member Function Documentation

void internal::BigInteger::AppendDecimal64 ( const char *  begin, const char *  end  )

inlineprivate

Definition at line 224 of file biginteger.h.

                                                             {
        uint64_t u = ParseUint64(begin, end);
        if (IsZero())
            *this = u;
        else {
            unsigned exp = static_cast<unsigned>(end - begin);
            (MultiplyPow5(exp) <<= exp) += u;   // *this = *this * 10^exp + u
        }
    }

int internal::BigInteger::Compare ( const BigInteger &  rhs ) const

inline

Definition at line 208 of file biginteger.h.

                                             {
        if (count_ != rhs.count_)
            return count_ < rhs.count_ ? -1 : 1;

        for (size_t i = count_; i-- > 0;)
            if (digits_[i] != rhs.digits_[i])
                return digits_[i] < rhs.digits_[i] ? -1 : 1;

        return 0;
    }

bool internal::BigInteger::Difference ( const BigInteger &  rhs, BigInteger *  out  ) const

inline

Definition at line 186 of file biginteger.h.

                                                                  {
        int cmp = Compare(rhs);
        RAPIDJSON_ASSERT(cmp != 0);
        const BigInteger *a, *b;  // Makes a > b
        bool ret;
        if (cmp < 0) { a = &rhs; b = this; ret = true; }
        else         { a = this; b = &rhs; ret = false; }

        Type borrow = 0;
        for (size_t i = 0; i < a->count_; i++) {
            Type d = a->digits_[i] - borrow;
            if (i < b->count_)
                d -= b->digits_[i];
            borrow = (d > a->digits_[i]) ? 1 : 0;
            out->digits_[i] = d;
            if (d != 0)
                out->count_ = i + 1;
        }

        return ret;
    }

size_t internal::BigInteger::GetCount ( ) const

inline

Definition at line 219 of file biginteger.h.

{ return count_; }

Type internal::BigInteger::GetDigit ( size_t  index ) const

inline

Definition at line 220 of file biginteger.h.

{ RAPIDJSON_ASSERT(index < count_); return digits_[index]; }

bool internal::BigInteger::IsZero ( ) const

inline

Definition at line 221 of file biginteger.h.

{ return count_ == 1 && digits_[0] == 0; }

static uint64_t internal::BigInteger::MulAdd64 ( uint64_t  a, uint64_t  b, uint64_t  k, uint64_t *  outHigh  )

inlinestaticprivate

Definition at line 249 of file biginteger.h.

                                                                                    {
#if defined(_MSC_VER) && defined(_M_AMD64)
        uint64_t low = _umul128(a, b, outHigh) + k;
        if (low < k)
            (*outHigh)++;
        return low;
#elif (__GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6)) && defined(__x86_64__)
        __extension__ typedef unsigned __int128 uint128;
        uint128 p = static_cast<uint128>(a) * static_cast<uint128>(b);
        p += k;
        *outHigh = static_cast<uint64_t>(p >> 64);
        return static_cast<uint64_t>(p);
#else
        const uint64_t a0 = a & 0xFFFFFFFF, a1 = a >> 32, b0 = b & 0xFFFFFFFF, b1 = b >> 32;
        uint64_t x0 = a0 * b0, x1 = a0 * b1, x2 = a1 * b0, x3 = a1 * b1;
        x1 += (x0 >> 32); // can't give carry
        x1 += x2;
        if (x1 < x2)
            x3 += (static_cast<uint64_t>(1) << 32);
        uint64_t lo = (x1 << 32) + (x0 & 0xFFFFFFFF);
        uint64_t hi = x3 + (x1 >> 32);

        lo += k;
        if (lo < k)
            hi++;
        *outHigh = hi;
        return lo;
#endif
    }

BigInteger& internal::BigInteger::MultiplyPow5 ( unsigned  exp )

inline

Definition at line 162 of file biginteger.h.

                                           {
        static const uint32_t kPow5[12] = {
            5,
            5 * 5,
            5 * 5 * 5,
            5 * 5 * 5 * 5,
            5 * 5 * 5 * 5 * 5,
            5 * 5 * 5 * 5 * 5 * 5,
            5 * 5 * 5 * 5 * 5 * 5 * 5,
            5 * 5 * 5 * 5 * 5 * 5 * 5 * 5,
            5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5,
            5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5,
            5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5,
            5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5 * 5
        };
        if (exp == 0) return *this;
        for (; exp >= 27; exp -= 27) *this *= RAPIDJSON_UINT64_C2(0X6765C793, 0XFA10079D); // 5^27
        for (; exp >= 13; exp -= 13) *this *= static_cast<uint32_t>(1220703125u); // 5^13
        if (exp > 0)                 *this *= kPow5[exp - 1];
        return *this;
    }

BigInteger& internal::BigInteger::operator*= ( uint64_t  u )

inline

Definition at line 87 of file biginteger.h.

                                       {
        if (u == 0) return *this = 0;
        if (u == 1) return *this;
        if (*this == 1) return *this = u;

        uint64_t k = 0;
        for (size_t i = 0; i < count_; i++) {
            uint64_t hi;
            digits_[i] = MulAdd64(digits_[i], u, k, &hi);
            k = hi;
        }
        
        if (k > 0)
            PushBack(k);

        return *this;
    }

BigInteger& internal::BigInteger::operator*= ( uint32_t  u )

inline

Definition at line 105 of file biginteger.h.

                                       {
        if (u == 0) return *this = 0;
        if (u == 1) return *this;
        if (*this == 1) return *this = u;

        uint64_t k = 0;
        for (size_t i = 0; i < count_; i++) {
            const uint64_t c = digits_[i] >> 32;
            const uint64_t d = digits_[i] & 0xFFFFFFFF;
            const uint64_t uc = u * c;
            const uint64_t ud = u * d;
            const uint64_t p0 = ud + k;
            const uint64_t p1 = uc + (p0 >> 32);
            digits_[i] = (p0 & 0xFFFFFFFF) | (p1 << 32);
            k = p1 >> 32;
        }
        
        if (k > 0)
            PushBack(k);

        return *this;
    }

BigInteger& internal::BigInteger::operator+= ( uint64_t  u )

inline

Definition at line 70 of file biginteger.h.

                                       {
        Type backup = digits_[0];
        digits_[0] += u;
        for (size_t i = 0; i < count_ - 1; i++) {
            if (digits_[i] >= backup)
                return *this; // no carry
            backup = digits_[i + 1];
            digits_[i + 1] += 1;
        }

        // Last carry
        if (digits_[count_ - 1] < backup)
            PushBack(1);

        return *this;
    }

BigInteger& internal::BigInteger::operator<<= ( size_t  shift )

inline

Definition at line 128 of file biginteger.h.

                                          {
        if (IsZero() || shift == 0) return *this;

        size_t offset = shift / kTypeBit;
        size_t interShift = shift % kTypeBit;
        RAPIDJSON_ASSERT(count_ + offset <= kCapacity);

        if (interShift == 0) {
            std::memmove(digits_ + offset, digits_, count_ * sizeof(Type));
            count_ += offset;
        }
        else {
            digits_[count_] = 0;
            for (size_t i = count_; i > 0; i--)
                digits_[i + offset] = (digits_[i] << interShift) | (digits_[i - 1] >> (kTypeBit - interShift));
            digits_[offset] = digits_[0] << interShift;
            count_ += offset;
            if (digits_[count_])
                count_++;
        }

        std::memset(digits_, 0, offset * sizeof(Type));

        return *this;
    }

BigInteger& internal::BigInteger::operator= ( const BigInteger &  rhs )

inline

Definition at line 55 of file biginteger.h.

    {
        if (this != &rhs) {
            count_ = rhs.count_;
            std::memcpy(digits_, rhs.digits_, count_ * sizeof(Type));
        }
        return *this;
    }

BigInteger& internal::BigInteger::operator= ( uint64_t  u )

inline

Definition at line 64 of file biginteger.h.

                                      {
        digits_[0] = u;            
        count_ = 1;
        return *this;
    }

bool internal::BigInteger::operator== ( const BigInteger &  rhs ) const

inline

Definition at line 154 of file biginteger.h.

                                                 {
        return count_ == rhs.count_ && std::memcmp(digits_, rhs.digits_, count_ * sizeof(Type)) == 0;
    }

bool internal::BigInteger::operator== ( const Type  rhs ) const

inline

Definition at line 158 of file biginteger.h.

                                          {
        return count_ == 1 && digits_[0] == rhs;
    }

static uint64_t internal::BigInteger::ParseUint64 ( const char *  begin, const char *  end  )

inlinestaticprivate

Definition at line 239 of file biginteger.h.

                                                                    {
        uint64_t r = 0;
        for (const char* p = begin; p != end; ++p) {
            RAPIDJSON_ASSERT(*p >= '0' && *p <= '9');
            r = r * 10u + static_cast<unsigned>(*p - '0');
        }
        return r;
    }

void internal::BigInteger::PushBack ( Type  digit )

inlineprivate

Definition at line 234 of file biginteger.h.

                              {
        RAPIDJSON_ASSERT(count_ < kCapacity);
        digits_[count_++] = digit;
    }

Member Data Documentation

size_t internal::BigInteger::count_

private

Definition at line 284 of file biginteger.h.

Type internal::BigInteger::digits_[kCapacity]

private

Definition at line 283 of file biginteger.h.

const size_t internal::BigInteger::kBitCount = 3328

staticprivate

Definition at line 279 of file biginteger.h.

const size_t internal::BigInteger::kCapacity = kBitCount / sizeof(Type)

staticprivate

Definition at line 280 of file biginteger.h.

const size_t internal::BigInteger::kTypeBit = sizeof(Type) * 8

staticprivate

Definition at line 281 of file biginteger.h.

---

The documentation for this class was generated from the following file:

• art/rapidjson/internal/biginteger.h