From 16d13e6f63d56ade031ad3e9489659a38fa1353f Mon Sep 17 00:00:00 2001
From: dinkc64 <12570148+dinkc64@users.noreply.github.com>
Date: Sat, 26 Mar 2016 00:19:18 +0000
Subject: [PATCH] fix crash issue with the ym2151 savestates when the current
 samplerate is different from samplerate when the state was made. a compromise
 was added to prevent breakage of all old savestate files

---
 src/burn/snd/burn_ym2151.cpp | 38 ++++++++++++++++++++++--------------
 1 file changed, 23 insertions(+), 15 deletions(-)

diff --git a/src/burn/snd/burn_ym2151.cpp b/src/burn/snd/burn_ym2151.cpp
index 8cc3e5f53..46d179c9d 100644
--- a/src/burn/snd/burn_ym2151.cpp
+++ b/src/burn/snd/burn_ym2151.cpp
@@ -234,21 +234,29 @@ void BurnYM2151Scan(INT32 nAction)
 		return;
 	}
 
-	SCAN_VAR(nBurnCurrentYM2151Register);
-	SCAN_VAR(BurnYM2151Registers);
-	SCAN_VAR(YM2151Volumes);
-	SCAN_VAR(YM2151RouteDirs);
-	SCAN_VAR(nBurnYM2151SoundRate);
-	SCAN_VAR(nBurnPosition);
-	SCAN_VAR(nSampleSize);
-	SCAN_VAR(nFractionalPosition);
-	SCAN_VAR(nSamplesRendered);
+	{
+		// A long time ago these variables were mistakenly scanned for the savestates.
+		// Recently it was found that this causes crash situations if the samplerate or
+		// sample size had changed between machines loading the states.
+		// These dummy variables are to prevent the breaking all states for games that use the 2151.
+		double dummyYM2151Volumes[2];
+		INT32 dummyYM2151RouteDirs[2];
+		INT32 dummynBurnYM2151SoundRate;
+		INT32 dummynBurnPosition;
+		UINT32 dummynSampleSize;
+		UINT32 dummynFractionalPosition;
+		UINT32 dummynSamplesRendered;
 
-	BurnYM2151Scan_int(nAction); // Properly scan the YM2151's internal registers
+		SCAN_VAR(nBurnCurrentYM2151Register);
+		SCAN_VAR(BurnYM2151Registers);
+		SCAN_VAR(dummyYM2151Volumes);
+		SCAN_VAR(dummyYM2151RouteDirs);
+		SCAN_VAR(dummynBurnYM2151SoundRate);
+		SCAN_VAR(dummynBurnPosition);
+		SCAN_VAR(dummynSampleSize);
+		SCAN_VAR(dummynFractionalPosition);
+		SCAN_VAR(dummynSamplesRendered);
+	}
 
-        /*if (nAction & ACB_WRITE) { // Restore the operator connections, see burn_ym2151.h BurnYM2151WriteRegister() for more info.
-		for (INT32 i = 0; i < 0x0100; i++) {
-			YM2151WriteReg(0, i, BurnYM2151Registers[i]);
-		}
-	}*/
+	BurnYM2151Scan_int(nAction); // Scan the YM2151's internal registers
 }