61 lines
2.0 KiB
C#
61 lines
2.0 KiB
C#
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using System;
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namespace Decentralized.Domain
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{
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/// <summary>
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/// 带种子、状态可存档的随机数（xoshiro128**）。游戏自己的 RNG 不带种子；mod 的事件、行情、暴毙都用这个，
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/// 状态随存档保存，读档后结果不变，测试也能复现。
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/// </summary>
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public sealed class Rng
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{
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public uint S0, S1, S2, S3;
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public Rng() : this(1) { }
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public Rng(ulong seed)
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{
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// SplitMix64 展开种子
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ulong z = seed;
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ulong Next()
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{
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z += 0x9E3779B97F4A7C15UL;
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ulong x = z;
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x = (x ^ (x >> 30)) * 0xBF58476D1CE4E5B9UL;
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x = (x ^ (x >> 27)) * 0x94D049BB133111EBUL;
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return x ^ (x >> 31);
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}
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ulong a = Next(), b = Next();
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S0 = (uint)a; S1 = (uint)(a >> 32); S2 = (uint)b; S3 = (uint)(b >> 32);
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if ((S0 | S1 | S2 | S3) == 0) S0 = 1;
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}
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private static uint Rotl(uint x, int k) => (x << k) | (x >> (32 - k));
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public uint NextUInt()
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{
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uint result = Rotl(S1 * 5, 7) * 9;
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uint t = S1 << 9;
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S2 ^= S0; S3 ^= S1; S1 ^= S2; S0 ^= S3;
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S2 ^= t;
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S3 = Rotl(S3, 11);
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return result;
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}
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/// <summary>[0, 1)</summary>
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public double NextDouble() => (NextUInt() >> 8) * (1.0 / (1 << 24));
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public bool Chance(double p) => NextDouble() < p;
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/// <summary>[min, max]，含两端。</summary>
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public int Range(int min, int max) => min + (int)(NextDouble() * (max - min + 1));
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public double Range(double min, double max) => min + NextDouble() * (max - min);
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/// <summary>标准正态（Box–Muller）。</summary>
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public double Gauss()
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{
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double u1 = 1.0 - NextDouble(), u2 = NextDouble();
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return Math.Sqrt(-2.0 * Math.Log(u1)) * Math.Cos(2.0 * Math.PI * u2);
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}
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}
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}
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