From bb4de6fcb0c86ecab3e5a4e937a2b6ed584de9c2 Mon Sep 17 00:00:00 2001
From: tildearrow <me@tildearrow.org>
Date: Wed, 6 Sep 2023 18:39:56 -0500
Subject: [PATCH] OPL/OPNA/OPNB: fix ADPCM-B freq not being clamped

---
 src/engine/platform/opl.cpp     | 2 ++
 src/engine/platform/ym2608.cpp  | 2 ++
 src/engine/platform/ym2610.cpp  | 2 ++
 src/engine/platform/ym2610b.cpp | 2 ++
 4 files changed, 8 insertions(+)

diff --git a/src/engine/platform/opl.cpp b/src/engine/platform/opl.cpp
index c8c5c944c..dff366d32 100644
--- a/src/engine/platform/opl.cpp
+++ b/src/engine/platform/opl.cpp
@@ -549,6 +549,8 @@ void DivPlatformOPL::tick(bool sysTick) {
           chan[adpcmChan].freq=5461; // 4KHz
         }
       }
+      if (chan[adpcmChan].freq<0) chan[adpcmChan].freq=0;
+      if (chan[adpcmChan].freq>65535) chan[adpcmChan].freq=65535;
       immWrite(16,chan[adpcmChan].freq&0xff);
       immWrite(17,(chan[adpcmChan].freq>>8)&0xff);
       if (chan[adpcmChan].keyOn || chan[adpcmChan].keyOff) {
diff --git a/src/engine/platform/ym2608.cpp b/src/engine/platform/ym2608.cpp
index 93c09fd67..dcab9dd5f 100644
--- a/src/engine/platform/ym2608.cpp
+++ b/src/engine/platform/ym2608.cpp
@@ -783,6 +783,8 @@ void DivPlatformYM2608::tick(bool sysTick) {
         chan[15].freq=0;
       }
     }
+    if (chan[adpcmBChanOffs].freq<0) chan[adpcmBChanOffs].freq=0;
+    if (chan[adpcmBChanOffs].freq>65535) chan[adpcmBChanOffs].freq=65535;
     immWrite(0x109,chan[15].freq&0xff);
     immWrite(0x10a,(chan[15].freq>>8)&0xff);
     hardResetElapsed+=2;
diff --git a/src/engine/platform/ym2610.cpp b/src/engine/platform/ym2610.cpp
index b7dcdb231..8b9295d9f 100644
--- a/src/engine/platform/ym2610.cpp
+++ b/src/engine/platform/ym2610.cpp
@@ -717,6 +717,8 @@ void DivPlatformYM2610::tick(bool sysTick) {
       } else {
         chan[adpcmBChanOffs].freq=0;
       }
+      if (chan[adpcmBChanOffs].freq<0) chan[adpcmBChanOffs].freq=0;
+      if (chan[adpcmBChanOffs].freq>65535) chan[adpcmBChanOffs].freq=65535;
       immWrite(0x19,chan[adpcmBChanOffs].freq&0xff);
       immWrite(0x1a,(chan[adpcmBChanOffs].freq>>8)&0xff);
       hardResetElapsed+=2;
diff --git a/src/engine/platform/ym2610b.cpp b/src/engine/platform/ym2610b.cpp
index fe5dbb581..7369265f9 100644
--- a/src/engine/platform/ym2610b.cpp
+++ b/src/engine/platform/ym2610b.cpp
@@ -784,6 +784,8 @@ void DivPlatformYM2610B::tick(bool sysTick) {
       } else {
         chan[adpcmBChanOffs].freq=0;
       }
+      if (chan[adpcmBChanOffs].freq<0) chan[adpcmBChanOffs].freq=0;
+      if (chan[adpcmBChanOffs].freq>65535) chan[adpcmBChanOffs].freq=65535;
       immWrite(0x19,chan[adpcmBChanOffs].freq&0xff);
       immWrite(0x1a,(chan[adpcmBChanOffs].freq>>8)&0xff);
       hardResetElapsed+=2;