From 39066900773e7857faf2d02e7ed51b71d219d97d Mon Sep 17 00:00:00 2001
From: godosa <godosa@godosa.eu>
Date: Tue, 6 Oct 2026 23:39:36 +0200
Subject: godosa-engine: initial public history

---
 src/Godosa.Core/Runs/SeedStreams.cs | 14 ++++++++++++++
 1 file changed, 14 insertions(+)
 create mode 100644 src/Godosa.Core/Runs/SeedStreams.cs

(limited to 'src/Godosa.Core/Runs/SeedStreams.cs')

diff --git a/src/Godosa.Core/Runs/SeedStreams.cs b/src/Godosa.Core/Runs/SeedStreams.cs
new file mode 100644
index 0000000..385d732
--- /dev/null
+++ b/src/Godosa.Core/Runs/SeedStreams.cs
@@ -0,0 +1,14 @@
+namespace Godosa.Core.Runs;
+
+/// <summary>Independent per-purpose seeds from one run seed: SplitMix64 output number <c>stream + 1</c> of
+/// <paramref name="seed"/> (audio draws then never shift the game's stream).</summary>
+public static class SeedStreams
+{
+    public static ulong Of(ulong seed, int stream)
+    {
+        var z = unchecked(seed + (ulong)(stream + 1) * 0x9E3779B97F4A7C15UL);
+        z = unchecked((z ^ (z >> 30)) * 0xBF58476D1CE4E5B9UL);
+        z = unchecked((z ^ (z >> 27)) * 0x94D049BB133111EBUL);
+        return z ^ (z >> 31);
+    }
+}
-- 
cgit