/*
 * File:   dclxvi-20130329/checkdouble.h
 * Author: Ruben Niederhagen, Peter Schwabe
 * Public Domain
 */

#ifndef CHECKDOUBLE_H
#define CHECKDOUBLE_H

#include <execinfo.h>
#include <inttypes.h>
#include <memory.h>
#include <stdlib.h>
#include <stdio.h>
#include <math.h>

#define MANTISSA_MAX ((1ULL << 53) - 1)

class CheckDouble{
  public: double v;
          unsigned long long mmax;

          CheckDouble()
          {
            v = NAN;
            mmax = MANTISSA_MAX;
          }

          CheckDouble(const double a)
          {
            v = a;
            mmax = (unsigned long long)fabs(a);
          }

          CheckDouble(const CheckDouble &a)
          {
            v = a.v;
            mmax = a.mmax;
          }

          CheckDouble(const double a, const unsigned long long int mmax)
          {
            v = a;
            this->mmax = mmax;
          }

          CheckDouble operator=(const CheckDouble &a)
          {
            v = a.v;
            mmax = a.mmax;
            return *this;
          }

          int operator==(const CheckDouble &a)const
          {
            return v == a.v;
          }

          int operator!=(const CheckDouble &a)const
          {
            return v != a.v;
          }

          CheckDouble operator+(const CheckDouble &a)const
          {
            if((mmax+a.mmax) > MANTISSA_MAX)
            {
              fprintf(stderr, "Overflow in %lf + %lf\n", v,a.v);
              fprintf(stderr, "Maximal values: %llu, %llu\n", mmax,a.mmax);
              abort();
            }
            return CheckDouble(a.v+v, mmax+a.mmax);
          }

          CheckDouble operator+=(const CheckDouble &a)
          {
            if((mmax+a.mmax) > MANTISSA_MAX)
            {
              fprintf(stderr, "Overflow in %lf += %lf\n", v,a.v);
              fprintf(stderr, "Maximal values: %llu, %llu\n", mmax,a.mmax);
              abort();
            }
            v += a.v;
            mmax += a.mmax;
            return *this;
          }

          CheckDouble operator-(const CheckDouble &a)const
          {
            if((mmax+a.mmax) > MANTISSA_MAX)
            {
              fprintf(stderr, "Overflow in %lf - %lf\n", v,a.v);
              fprintf(stderr, "Maximal values: %llu, %llu\n", mmax,a.mmax);
              abort();
            }
            return CheckDouble(v-a.v, mmax+a.mmax);
          }

          CheckDouble operator-=(const CheckDouble &a)
          {
            if((mmax+a.mmax) > MANTISSA_MAX)
            {
              fprintf(stderr, "Overflow in %lf += %lf\n", v,a.v);
              fprintf(stderr, "Maximal values: %llu, %llu\n", mmax,a.mmax);
              abort();
            }
            v -= a.v;
            mmax += a.mmax;
            return *this;
          }

          CheckDouble operator-()const
          {
            return CheckDouble(-v, mmax);
          }

          CheckDouble operator*(const CheckDouble &a)const
          {
            uint64_t l1 = mmax & 0xffffffff;
            uint64_t l2 = a.mmax & 0xffffffff;
            uint64_t u1 = mmax >> 32;
            uint64_t u2 = a.mmax >> 32;
            unsigned long long upper = u1 * u2;
            if(upper != 0)
            {
              fprintf(stderr, "Overflow in %lf * %lf\n", v,a.v);
              fprintf(stderr, "Maximal values: %llu, %llu\n", mmax,a.mmax);
              abort();
            }
            unsigned long long mid = l1 * u2 + u1 * l2;
            unsigned long long lower = l1 * l2;
            if(lower >= MANTISSA_MAX)
            {
              fprintf(stderr, "Overflow in %lf * %lf\n", v,a.v);
              fprintf(stderr, "Maximal values: %llu, %llu\n", mmax,a.mmax);
              abort();
            }
            if(mid > (MANTISSA_MAX>>32))
            {
              fprintf(stderr, "Overflow in %lf * %lf\n", v,a.v);
              fprintf(stderr, "Maximal values: %llu, %llu\n", mmax,a.mmax);
              abort();
            }
            lower += (mid <<32);
            if(lower > MANTISSA_MAX)
            {
              fprintf(stderr, "Overflow in %lf * %lf\n", v,a.v);
              fprintf(stderr, "Maximal values: %llu, %llu\n", mmax,a.mmax);
              abort();
            }
            return CheckDouble(v*a.v, mmax*a.mmax);
          }

          CheckDouble operator/(const double &a)const
          {
            if(mmax/fabs(a) > MANTISSA_MAX)
            {
              fprintf(stderr, "Overflow in %lf / %lf\n", v,a);
              fprintf(stderr, "Maximal values: %llu, %lf\n", mmax,a);
              abort();
            }
            return CheckDouble(v/a, mmax/(unsigned long long)fabs(a)+1);
          }

          CheckDouble operator*=(const int b) 
          {
            CheckDouble op((double) b, abs(b));
            *this = *this * op;
            return *this;
          }

          /*
          friend CheckDouble operator*(const CheckDouble &a,const int b) 
          {
            CheckDouble op((double) b, abs(b));
            return op * a;
          }
          */
          
          friend CheckDouble operator*(const int32_t b, const CheckDouble &a) 
          {
            CheckDouble op((double) b, abs(b));
            return op * a;
          }

          friend int operator<(const CheckDouble &op1, const CheckDouble &op2)
          {
            return op1.v < op2.v;
          }
          
          friend int operator<=(const CheckDouble &op1, const CheckDouble &op2)
          {
            return op1.v <= op2.v;
          }

          friend int operator>(const CheckDouble &op1, const CheckDouble &op2)
          {
            return op1.v > op2.v;
          }

          friend int operator>=(const CheckDouble &op1, const CheckDouble &op2)
          {
            return op1.v >= op2.v;
          }

          friend CheckDouble round(const CheckDouble &a)
          {
            return CheckDouble(round(a.v),a.mmax);
          }
          
          friend CheckDouble trunc(const CheckDouble &a)
          {
            return CheckDouble(trunc(a.v),a.mmax);
          }

          friend CheckDouble remround(const CheckDouble &a, const double d)
          {
            double carry = round(a.v/d);
            return CheckDouble(a.v - carry*d, (unsigned long long)((d+1)/2));
          }

          friend long long ftoll(const CheckDouble &arg)
          {
            return (long long)arg.v;
          }

          friend void setmax(CheckDouble &arg, unsigned long long max)
          {
            arg.mmax = max;
          }

          friend double todouble(const CheckDouble &arg)
          {
            return arg.v;
          }
};

int printfoff(...);

#endif // #ifndef CHECKDOUBLE_H