Work in progress

Author: skhaz

_posts/2025-08-02-replacing-lua-s-math-random-module-with-the-xorshift-algorithm.md

@@ -26,10 +26,11 @@ Anyway, I ended up replacing Lua’s implementation with the one below, because
 ```cpp
 static std::array<uint64_t, 2> prng_state;
 
-void seed(const uint64_t a, uint64_t b) {
-  if (a == 0 && b == 0) b = 1;
-  prng_state[0] = a;
-  prng_state[1] = b;
+void seed(uint64_t value) {
+  constexpr uint64_t mix = 0xdeadbeefcafebabeULL;
+  if (value == 0) value = 1;
+  prng_state[0] = value;
+  prng_state[1] = value ^ mix;
 }
 
 uint64_t xorshift128plus() {
@@ -56,8 +57,7 @@ lua_Integer xorshift_random_int(const lua_Integer low, const lua_Integer high) {
 }
 
 const auto now = std::chrono::high_resolution_clock::now().time_since_epoch().count();
-const auto seed_val = static_cast<uint64_t>(now);
-seed(seed_val, seed_val ^ 0xdeadbeefcafebabeULL);
+seed(static_cast<uint64_t>(now));
 
 lua["math"]["random"] = sol::overload(
   []() -> double {
@@ -72,7 +72,6 @@ lua["math"]["random"] = sol::overload(
 );
 
 lua["math"]["randomseed"] = [](lua_Integer seed_value) {
-  const uint64_t s = static_cast<uint64_t>(seed_value);
-  seed(s, s ^ 0xdeadbeefcafebabeULL);
+  seed(static_cast<uint64_t>(seed_value));
 };
 ```