use a fixed seed for prng (official-stockfish#368)

xu-shawn · web-flow · commit c8ad581b9226 · 2025-10-13T22:09:08.000+02:00
diff --git a/lib/rng.h b/lib/rng.h
@@ -4,9 +4,10 @@
 
 namespace rng
 {
-    inline auto& get_thread_local_rng()
+    template <typename RNG = std::mt19937_64>
+    auto& get_thread_local_rng(typename RNG::result_type seed = RNG::default_seed)
     {
-        static thread_local std::mt19937_64 s_rng(std::random_device{}());
+        static thread_local RNG s_rng(seed);
         return s_rng;
     }
 }

Original file line number	Diff line number	Diff line change
`@@ -4,9 +4,10 @@`
`4`	`4`
`5`	`5`	`namespace rng`
`6`	`6`	`{`
`7`		`- inline auto& get_thread_local_rng()`
	`7`	`+ template <typename RNG = std::mt19937_64>`
	`8`	`+ auto& get_thread_local_rng(typename RNG::result_type seed = RNG::default_seed)`
`8`	`9`	`{`
`9`		`- static thread_local std::mt19937_64 s_rng(std::random_device{}());`
	`10`	`+ static thread_local RNG s_rng(seed);`
`10`	`11`	`return s_rng;`
`11`	`12`	`}`
`12`	`13`	`}`