From 92da7c45ef7d2aa42d662558a198229f229089b0 Mon Sep 17 00:00:00 2001
From: Peter Veenstra <qbix79@users.sourceforge.net>
Date: Mon, 11 Nov 2019 17:23:05 +0000
Subject: [PATCH] Switch to a different way to calculate the table offsets.
 Thanks jmarsh

Imported-from: https://svn.code.sf.net/p/dosbox/code-0/dosbox/trunk@4282
---
 src/hardware/dbopl.cpp | 9 +++------
 src/hardware/dbopl.h   | 8 ++++----
 2 files changed, 7 insertions(+), 10 deletions(-)

diff --git a/src/hardware/dbopl.cpp b/src/hardware/dbopl.cpp
index acbf2b8f..0a616c40 100644
--- a/src/hardware/dbopl.cpp
+++ b/src/hardware/dbopl.cpp
@@ -37,6 +37,7 @@
 #include <math.h>
 #include <stdlib.h>
 #include <string.h>
+#include <stddef.h>
 #include "dosbox.h"
 #include "dbopl.h"
 
@@ -1430,7 +1431,6 @@ void InitTables( void ) {
 		TremoloTable[TREMOLO_TABLE - 1 - i] = val;
 	}
 	//Create a table with offsets of the channels from the start of the chip
-	DBOPL::Chip* chip = 0;
 	for ( Bitu i = 0; i < 32; i++ ) {
 		Bitu index = i & 0xf;
 		if ( index >= 9 ) {
@@ -1444,8 +1444,7 @@ void InitTables( void ) {
 		//Add back the bits for highest ones
 		if ( i >= 16 )
 			index += 9;
-		Bitu blah = reinterpret_cast<Bitu>( &(chip->chan[ index ]) );
-		ChanOffsetTable[i] = blah;
+		ChanOffsetTable[i] = (Bit16u)(index*sizeof(DBOPL::Channel));
 	}
 	//Same for operators
 	for ( Bitu i = 0; i < 64; i++ ) {
@@ -1458,9 +1457,7 @@ void InitTables( void ) {
 		if ( chNum >= 12 )
 			chNum += 16 - 12;
 		Bitu opNum = ( i % 8 ) / 3;
-		DBOPL::Channel* chan = 0;
-		Bitu blah = reinterpret_cast<Bitu>( &(chan->op[opNum]) );
-		OpOffsetTable[i] = ChanOffsetTable[ chNum ] + blah;
+		OpOffsetTable[i] = ChanOffsetTable[chNum]+(Bit16u)(opNum*sizeof(DBOPL::Operator));
 	}
 #if 0
 	//Stupid checks if table's are correct
diff --git a/src/hardware/dbopl.h b/src/hardware/dbopl.h
index addaed77..97dc7cac 100644
--- a/src/hardware/dbopl.h
+++ b/src/hardware/dbopl.h
@@ -156,7 +156,7 @@ public:
 };
 
 struct Channel {
-	Operator op[2];
+	Operator op[2]; //Leave on top of struct for simpler pointer math.
 	inline Operator* Op( Bitu index ) {
 		return &( ( this + (index >> 1) )->op[ index & 1 ]);
 	}
@@ -192,6 +192,9 @@ struct Channel {
 };
 
 struct Chip {
+	//18 channels with 2 operators each. Leave on top of struct for simpler pointer math.
+	Channel chan[18];
+
 	//This is used as the base counter for vibrato and tremolo
 	Bit32u lfoCounter;
 	Bit32u lfoAdd;
@@ -208,9 +211,6 @@ struct Chip {
 	//Best match attack rates for the rate of this chip
 	Bit32u attackRates[76];
 
-	//18 channels with 2 operators each
-	Channel chan[18];
-
 	Bit8u reg104;
 	Bit8u reg08;
 	Bit8u reg04;