Beispiel #1
0
   public static EInteger ReduceTrailingZeros(
       EInteger bigmant,
       FastInteger exponentMutable,
       int radix,
       FastInteger digits,
       FastInteger precision,
       FastInteger idealExp)
   {
 #if DEBUG
       if (precision != null && digits == null)
       {
           throw new ArgumentException("doesn't satisfy precision==null ||" +
                                       "\u0020digits!=null");
       }
       if (!(bigmant.Sign >= 0))
       {
           throw new ArgumentException("doesn't satisfy bigmant.Sign >= 0");
       }
 #endif
       if (bigmant.IsZero)
       {
           exponentMutable.SetInt(0);
           return(bigmant);
       }
       if (radix == 2)
       {
           if (!bigmant.IsEven)
           {
               return(bigmant);
           }
           long lowbit = bigmant.GetLowBitAsInt64();
           if (lowbit != Int64.MaxValue)
           {
               if (precision != null && digits.CompareTo(precision) >= 0)
               {
                   // Limit by digits minus precision
                   EInteger tmp = digits.ToEInteger().Subtract(precision.ToEInteger());
                   if (tmp.CompareTo(EInteger.FromInt64(lowbit)) < 0)
                   {
                       lowbit = tmp.ToInt64Checked();
                   }
               }
               if (idealExp != null && exponentMutable.CompareTo(idealExp) <= 0)
               {
                   // Limit by idealExp minus exponentMutable
                   EInteger tmp =
                       idealExp.ToEInteger().Subtract(exponentMutable.ToEInteger());
                   if (tmp.CompareTo(EInteger.FromInt64(lowbit)) < 0)
                   {
                       lowbit = tmp.ToInt64Checked();
                   }
               }
               bigmant = (lowbit <= Int32.MaxValue) ?
                         bigmant.ShiftRight((int)lowbit) :
                         bigmant.ShiftRight(EInteger.FromInt64(lowbit));
               if (digits != null)
               {
                   digits.SubtractInt64(lowbit);
               }
               if (exponentMutable != null)
               {
                   exponentMutable.AddInt64(lowbit);
               }
               return(bigmant);
           }
       }
       var bigradix    = (EInteger)radix;
       var bitsToShift = new FastInteger(0);
       while (!bigmant.IsZero)
       {
           if (precision != null && digits.CompareTo(precision) == 0)
           {
               break;
           }
           if (idealExp != null && exponentMutable.CompareTo(idealExp) == 0)
           {
               break;
           }
           EInteger   bigrem;
           EInteger   bigquo;
           EInteger[] divrem = bigmant.DivRem(bigradix);
           bigquo = divrem[0];
           bigrem = divrem[1];
           if (!bigrem.IsZero)
           {
               break;
           }
           bigmant = bigquo;
           exponentMutable.Increment();
           if (digits != null)
           {
               digits.Decrement();
           }
       }
       return(bigmant);
   }