private uint NextUInt32(uint maxValue)
{
if (maxValue == 0)
{
return(0);
}
// determine the position of MSB
uint mask;
if (maxValue == this.cachedMaxValue)
{
mask = this.cachedValueMask;
}
else
{
this.cachedMaxValue = maxValue;
mask = this.cachedValueMask = BitScanner.Mask(maxValue - 1);
}
//
uint num;
do
{
num = this.NextUInt32();
num &= mask;
} while (num >= maxValue);
return(num);
}
private static double FullPrecisionDouble_c0o1(Random rng, byte[] buffer)
{
const int EffectiveBits = BUFFER_SIZE * 8;
// exponent
var e = -1;
do
{
rng.NextBytes(buffer);
var r = BitConverter.ToUInt64(buffer, 0);
var ntz = BitScanner.NumberOfTrailingZeros64(r);
if (ntz < EffectiveBits)
{
e -= ntz;
break;
}
e -= EffectiveBits;
} while (e > -1024);
//
if (e <= -1024)
{
return(0);
}
// fraction
rng.NextBytes(buffer);
var f = (long)(BitConverter.ToUInt64(buffer, 0) >> 12);
// IEEE-754
return(BitConverter.Int64BitsToDouble(((long)(e + 1023) << 52) | f));
}
