From 691a550618a112a595837f6f14d2268240de682a Mon Sep 17 00:00:00 2001
From: Barry Harris <44396066+barry65536@users.noreply.github.com>
Date: Thu, 12 Mar 2015 23:11:01 +0000
Subject: [PATCH] SMS - Mix YM & SN Sound

---
 src/burn/drv/sms/smssound.cpp  |  2 +-
 src/burn/drv/sms/smssystem.cpp | 15 +++++++++++----
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/burn/drv/sms/smssound.cpp b/src/burn/drv/sms/smssound.cpp
index 17c9fd783..aa4f33fe6 100644
--- a/src/burn/drv/sms/smssound.cpp
+++ b/src/burn/drv/sms/smssound.cpp
@@ -23,7 +23,7 @@ INT32 sound_init(void)
         return 0;
 
     // Init sound emulation
-	SN76489Init(0, snd.psg_clock, 0);
+	SN76489Init(0, snd.psg_clock, 1);
 	SN76496SetRoute(0, 0.70, BURN_SND_ROUTE_BOTH);
 
 	FM_Init();
diff --git a/src/burn/drv/sms/smssystem.cpp b/src/burn/drv/sms/smssystem.cpp
index 5c53a0cf5..c16780af6 100644
--- a/src/burn/drv/sms/smssystem.cpp
+++ b/src/burn/drv/sms/smssystem.cpp
@@ -106,9 +106,13 @@ void system_frame(INT32 skip_render)
 		if (pBurnSoundOut) {
 			INT32 nSegmentLength = nBurnSoundLen / lpf;
 			INT16* pSoundBuf = pBurnSoundOut + (nSoundBufferPos << 1);
-			SN76496Update(0, pSoundBuf, nSegmentLength);
-			if (sms.use_fm)
+			if (sms.use_fm)	{
 				BurnYM2413Render(pSoundBuf, nSegmentLength);
+			} else {
+				memset(pSoundBuf, 0, nSegmentLength * 2 * sizeof(INT16));
+			}
+			SN76496Update(0, pSoundBuf, nSegmentLength);
+			
 			nSoundBufferPos += nSegmentLength;
 		}
 
@@ -123,9 +127,12 @@ void system_frame(INT32 skip_render)
 		INT32 nSegmentLength = nBurnSoundLen - nSoundBufferPos;
 		INT16* pSoundBuf = pBurnSoundOut + (nSoundBufferPos << 1);
 		if (nSegmentLength) {
-			SN76496Update(0, pSoundBuf, nSegmentLength);
-			if (sms.use_fm)
+			if (sms.use_fm)	{
 				BurnYM2413Render(pSoundBuf, nSegmentLength);
+			} else {
+				memset(pSoundBuf, 0, nSegmentLength * 2 * sizeof(INT16));
+			}
+			SN76496Update(0, pSoundBuf, nSegmentLength);
 		}
 	}
 }