用reflector看到C#Random类的实现

[Serializable, ComVisible(true)]
public class Random
{
// Fields
private int inext;
private int inextp;
private const int MBIG = 0x7fffffff;
private const int MSEED = 0x9a4ec86;
private const int MZ = 0;
private int[] SeedArray;

// Methods
public Random() : this(Environment.TickCount)
{
}

public Random(int Seed)
{
this.SeedArray = new int[0x38];
int num2 = 0x9a4ec86 - Math.Abs(Seed);
this.SeedArray[0x37] = num2;
int num3 = 1;
for (int i = 1; i < 0x37; i++)
{
int index = (0x15 * i) % 0x37;
this.SeedArray[index] = num3;
num3 = num2 - num3;
if (num3 < 0)
{
num3 += 0x7fffffff;
}
num2 = this.SeedArray[index];
}
for (int j = 1; j < 5; j++)
{
for (int k = 1; k < 0x38; k++)
{
this.SeedArray[k] -= this.SeedArray[1 + ((k + 30) % 0x37)];
if (this.SeedArray[k] < 0)
{
this.SeedArray[k] += 0x7fffffff;
}
}
}
this.inext = 0;
this.inextp = 0x15;
Seed = 1;
}

private double GetSampleForLargeRange()
{
int num = this.InternalSample();
if ((this.InternalSample() % 2) == 0)
{
num = -num;
}
double num2 = num;
num2 += 2147483646.0;
return (num2 / 4294967293);
}

private int InternalSample()
{
int inext = this.inext;
int inextp = this.inextp;
if (++inext >= 0x38)
{
inext = 1;
}
if (++inextp >= 0x38)
{
inextp = 1;
}
int num = this.SeedArray[inext] - this.SeedArray[inextp];
if (num < 0)
{
num += 0x7fffffff;
}
this.SeedArray[inext] = num;
this.inext = inext;
this.inextp = inextp;
return num;
}

public virtual int Next()
{
return this.InternalSample();
}

public virtual int Next(int maxValue)
{
if (maxValue < 0)
{
throw new ArgumentOutOfRangeException("maxValue", string.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("ArgumentOutOfRange_MustBePositive"), new object[] { "maxValue" }));
}
return (int) (this.Sample() * maxValue);
}

public virtual int Next(int minValue, int maxValue)
{
if (minValue > maxValue)
{
throw new ArgumentOutOfRangeException("minValue", string.Format(CultureInfo.CurrentCulture, Environment.GetResourceString("Argument_MinMaxValue"), new object[] { "minValue", "maxValue" }));
}
long num = maxValue - minValue;
if (num <= 0x7fffffffL)
{
return (((int) (this.Sample() * num)) + minValue);
}
return (((int) ((long) (this.GetSampleForLargeRange() * num))) + minValue);
}

public virtual void NextBytes(byte[] buffer)
{
if (buffer == null)
{
throw new ArgumentNullException("buffer");
}
for (int i = 0; i < buffer.Length; i++)
{
buffer[i] = (byte) (this.InternalSample() % 0x100);
}
}

public virtual double NextDouble()
{
return this.Sample();
}

protected virtual double Sample()
{
return (this.InternalSample() * 4.6566128752457969E-10);
}
}