SeedRandom.cs

using System;

namespace SuperMetroidRandomizer.Random
{
	public class SeedRandom
	{
	    private int inext;
		private int inextp;
		private readonly int[] SeedArray = new int[56];
		
        public SeedRandom() : this(Environment.TickCount)
		{
		}
		
        public SeedRandom(int Seed)
		{
			int num = (Seed == -2147483648) ? 2147483647 : Math.Abs(Seed);
			int num2 = 161803398 - num;
			SeedArray[55] = num2;
			int num3 = 1;
			for (int i = 1; i < 55; i++)
			{
				int num4 = 21 * i % 55;
				SeedArray[num4] = num3;
				num3 = num2 - num3;
				if (num3 < 0)
				{
					num3 += 2147483647;
				}
				num2 = SeedArray[num4];
			}
			for (int j = 1; j < 5; j++)
			{
				for (int k = 1; k < 56; k++)
				{
					SeedArray[k] -= SeedArray[1 + (k + 30) % 55];
					if (SeedArray[k] < 0)
					{
						SeedArray[k] += 2147483647;
					}
				}
			}
			inext = 0;
			inextp = 21;
		}
		
        protected virtual double Sample()
		{
			return InternalSample() * 4.6566128752457969E-10;
		}
		
        private int InternalSample()
		{
			int num = inext;
			int num2 = inextp;
			if (++num >= 56)
			{
				num = 1;
			}
			if (++num2 >= 56)
			{
				num2 = 1;
			}
			int num3 = SeedArray[num] - SeedArray[num2];
			if (num3 == 2147483647)
			{
				num3--;
			}
			if (num3 < 0)
			{
				num3 += 2147483647;
			}
			SeedArray[num] = num3;
			inext = num;
			inextp = num2;
			return num3;
		}
		
        public virtual int Next()
		{
			return InternalSample();
		}
		
        private double GetSampleForLargeRange()
		{
			int num = InternalSample();
			bool flag = InternalSample() % 2 == 0;
			if (flag)
			{
				num = -num;
			}
			double num2 = num;
			num2 += 2147483646.0;
			return num2 / 4294967293.0;
		}
		
        public virtual int Next(int minValue, int maxValue)
		{
			if (minValue > maxValue)
			{
                throw new ArgumentOutOfRangeException("minValue", "minValue must be less than maxValue.");
			}
			long num = maxValue - (long)minValue;
			if (num <= 2147483647L)
			{
				return (int)(Sample() * num) + minValue;
			}
			return (int)((long)(GetSampleForLargeRange() * num) + minValue);
		}
		
        public virtual int Next(int maxValue)
		{
			if (maxValue < 0)
			{
                throw new ArgumentOutOfRangeException("maxValue", "maxValue must be positive.");
			}
			return (int)(Sample() * maxValue);
		}
		
        public virtual double NextDouble()
		{
			return Sample();
		}

        public virtual void NextBytes(byte[] buffer)
		{
			if (buffer == null)
			{
				throw new ArgumentNullException("buffer");
			}
			for (int i = 0; i < buffer.Length; i++)
			{
				buffer[i] = (byte)(InternalSample() % 256);
			}
		}
	}
}