public int CompareTo(BigFloat that) {
if (this.exponent > that.exponent)
return 1;
if (this.exponent < that.exponent)
return -1;
if (this.significand == that.significand)
return 0;
return this.significand > that.significand ? 1 : -1;
}
void Float(out BigFloat n) {
string s = "";
Expect(7);
s = t.val;
try {
n = BigFloat.FromString(s);
} catch (FormatException e) {
this.SemErr("incorrectly formatted floating point, " + e.Message);
n = BigFloat.ZERO;
}
}
public static BigFloat operator +(BigFloat x, BigFloat y)
{
Contract.Requires(x.exponentSize == y.exponentSize);
Contract.Requires(x.significandSize == y.significandSize);
if (x.value != "" || y.value != "")
{
if (x.value == "NaN" || y.value == "NaN" || x.value == "+oo" && y.value == "-oo" ||
x.value == "-oo" && y.value == "+oo")
{
return(new BigFloat("NaN", x.significandSize, x.exponentSize));
}
if (x.value != "")
{
return(new BigFloat(x.value, x.significandSize, x.exponentSize));
}
return(new BigFloat(y.value, y.significandSize, y.exponentSize));
}
if (x.exponent > y.exponent)
{
BigFloat temp = x;
x = y;
y = temp;
}
BIM xsig = x.significand, ysig = y.significand;
BIM xexp = x.exponent, yexp = y.exponent;
if (yexp - xexp > x.significandSize) //One of the numbers is relatively insignificant
{
return(new BigFloat(y.isSignBitSet, y.significand, y.exponent, y.significandSize, y.exponentSize));
}
BIM hiddenBitPow = BIM.Pow(2, x.significandSize - 1);
if (xexp > 0)
{
xsig += hiddenBitPow;
}
else
{
++xexp;
}
if (yexp > 0)
{
ysig += hiddenBitPow;
}
else
{
++yexp;
}
if (x.isSignBitSet)
{
xsig = -xsig;
}
if (y.isSignBitSet)
{
ysig = -ysig;
}
xsig >>= (int)(yexp - xexp); //Guaranteed to fit in a 32-bit integer
ysig += xsig;
bool isNeg = ysig < 0;
ysig = BIM.Abs(ysig);
if (ysig == 0)
{
return(new BigFloat(x.isSignBitSet && y.isSignBitSet, 0, 0, x.significandSize, x.exponentSize));
}
if (ysig >= hiddenBitPow * 2)
{
ysig >>= 1;
++yexp;
}
while (ysig < hiddenBitPow && yexp > 1)
{
ysig <<= 1;
--yexp;
}
if (ysig < hiddenBitPow)
{
yexp = 0;
}
else
{
ysig -= hiddenBitPow;
}
if (yexp >= BIM.Pow(2, x.exponentSize) - 1)
{
return(new BigFloat(y.isSignBitSet ? "-oo" : "+oo", x.significandSize, x.exponentSize));
}
return(new BigFloat(isNeg, ysig, yexp, x.significandSize, x.exponentSize));
}
