public static void ThrowIfUndefined(this BigNum value)
{
value.ThrowIfNullArg();
if (value.IsUndefined)
{
throw new InvalidOperationException("Value is undefined.");
}
}
public static BigNum Pow2(int exponent)
{
if (exponent < 0)
{
var one = new BigNum("1");
return(one / Pow2(-exponent));
}
return(new BigNum(BigInteger.Pow(2, exponent).ToString()));
}
private unsafe void ParseDouble(double value)
{
if (double.IsNegativeInfinity(value) || double.IsPositiveInfinity(value) || double.IsNaN(value))
{
IsUndefined = true;
_exponent = 0;
_number = 0;
}
else
{
ulong bits = ((ulong *)&value)[0];
/* Determine whether or not the number is negative. */
bool isNegative = (int)((bits >> 63) & 0x1) != 0;
/* Grab the exponent portion of the double (63 - 52 = 11 bits max) */
int shift = (int)((int)(bits >> 52) & DoubleExponentMask);
shift -= DoubleExponentShiftValue;
/* Grab the exponent portion */
ulong fraction = bits & DoubleFractionMask;
if (shift != 0)
{
fraction |= (ulong)BigInteger.Pow(2, 52);
}
BigNum fractionBigNum = new BigNum(fraction.ToString());
fractionBigNum *= Pow2(shift - 52);
_number = fractionBigNum._number;
_exponent = fractionBigNum._exponent;
if (fraction == 0 && shift == 0)
{
_number = 1;
}
if (isNegative)
{
_number *= -1;
}
}
}
/// <summary>
/// Determines whether or not <seealso cref="double"/>.ToString(), for the specified value, generates an
/// exact representation of the stored value.
/// </summary>
/// <param name="value">The <seealso cref="double"/> to check.</param>
/// <returns>True if the <seealso cref="double"/>'s .ToString() is exact; false otherwise.</returns>
public static bool IsToStringCorrect(double value)
{
BigNum doubleVersion = new BigNum(value, false);
BigNum stringVersion = new BigNum(value, true);
var doubleVersionString = doubleVersion.ToString();
var stringVersrionString = stringVersion.ToString();
if (doubleVersionString.Length < stringVersrionString.Length)
{
return(false);
}
for (int i = 0; i < doubleVersionString.Length; i++)
{
if (doubleVersionString[i] != stringVersrionString[i])
{
return(false);
}
}
return(true);
}
