From 483da49759da28fe7540ae6edf43aa4c7971faf2 Mon Sep 17 00:00:00 2001
From: phosit <phosit@wildfiregames.com>
Date: Fri, 16 Feb 2024 17:31:40 +0000
Subject: [PATCH] More generic hash function for FSM

The hash function introduced in 6faf704731 doesn't work on 32 bit
systems. This one should.

Accepted By: @vladislavbelov
Differential Revision: https://code.wildfiregames.com/D5237
This was SVN commit r28033.
---
 source/network/FSM.h | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/source/network/FSM.h b/source/network/FSM.h
index f27d3d6a1b..fab678421b 100644
--- a/source/network/FSM.h
+++ b/source/network/FSM.h
@@ -170,10 +170,10 @@ private:
 		{
 			size_t operator()(const TransitionKey& key) const noexcept
 			{
-				static_assert(sizeof(UnderlyingType) <= sizeof(size_t) / 2);
-				return (static_cast<size_t>(key.state) <<
-					((sizeof(size_t) / 2) * std::numeric_limits<unsigned char>::digits)) +
-					static_cast<size_t>(key.eventType);
+				constexpr size_t count{std::numeric_limits<size_t>::digits / 2};
+				const size_t wideState{static_cast<size_t>(key.state)};
+				const size_t rotatedState{(wideState << count) | (wideState >> count)};
+				return static_cast<size_t>(key.eventType) ^ rotatedState;
 			}
 		};