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#pragma once

class Int128

{

public:

        __int64 low;

        __int64 high;

public:

        static Int128 *Zero() {

                static Int128 zr;

                zr.low = 0LL;

                zr.high = 0LL;

                return (&zr);

        };

        static Int128 *One() {

                static Int128 zr;

                zr.low = 1LL;

                zr.high = 0LL;

                return (&zr);

        };

        static void Assign(Int128 *a, Int128 *b) {

                a->low = b->low;

                a->high = b->high;

        };

        //fnASCarry = op? (~a&b)|(s&~a)|(s&b) : (a&b)|(a&~s)|(b&~s);

        // Compute carry bit from 64 bit addition.

        static bool AddCarry(__int64 s, __int64 a, __int64 b) {

                return (((a&b)|(a&~s)|(b&~s)) >> 63LL);

        };

        // Compute carry bit from 64 bit subtraction.

        static bool SubBorrow(__int64 s, __int64 a, __int64 b) {

                return (((~a&b)|(s&~a)|(s&b)) >> 63LL);

        };

        // Add two 128 bit numbers.

        static bool Add(Int128 *sum, Int128 *a, Int128 *b);

        // Subtract two 128 bit numbers.

        static bool Sub(Int128 *sum, Int128 *a, Int128 *b);

        // Shift left one bit.

        static bool Shl(Int128 *o, Int128 *a);

        static bool Shr(Int128 *o, Int128 *a);

        static void Mul(Int128 *p, Int128 *a, Int128 *b);

        static void Div(Int128 *q, Int128 *r, Int128 *a, Int128 *b);

        static bool IsEqual(Int128 *a, Int128 *b);

        static bool IsLessThan(Int128 *a, Int128 *b);

};