public static uint MulOvf(uint x, uint y)
{
int m = Tricks.Nlz(x);
int n = Tricks.Nlz(y);
if (m + n <= 30)
{
throw new OverflowException();
}
uint t = x * (y >> 1);
if ((int)t < 0)
{
throw new OverflowException();
}
uint z = t * 2;
if ((y & 1) != 0)
{
z = z + x;
if (z < x)
{
throw new OverflowException();
}
}
return(z);
}
public void TestNlzBitwiseViaNlz()
{
for (int i = -100; i < 100; ++i)
{
Assert.AreEqual(Tricks.NlzBitwise((uint)i), Tricks.Nlz((uint)i));
}
}
public void TestNLZ()
{
Assert.AreEqual(32, Tricks.Nlz(0));
Assert.AreEqual(31, Tricks.Nlz(1));
Assert.AreEqual(16, Tricks.Nlz(0x0000FFFF));
Assert.AreEqual(14, Tricks.Nlz(0x0003FFFF));
Assert.AreEqual(0, Tricks.Nlz(0xF000FFFF));
}
public static int GetMinBits(this int value)
{
uint v = (uint)value;
if (value >= 0)
{
return(v.GetMinBits() + 1);
}
v = ~v;
int n = Tricks.Nlz(v);
return(33 - n);
}
public static int GetMinBits(this uint value)
{
return(32 - Tricks.Nlz(value));
}
