From 34d092556994b23829ff23e111a2fb6dfd541f78 Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Mon, 16 May 2022 21:06:49 -0500
Subject: [PATCH] OPL: fix fixed frequency drums

---
 TODO.md                     | 1 -
 src/engine/platform/opl.cpp | 9 ++++++---
 src/engine/platform/opl.h   | 3 ++-
 3 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/TODO.md b/TODO.md
index 94e7f8df6..62364e065 100644
--- a/TODO.md
+++ b/TODO.md
@@ -1,6 +1,5 @@
 # to-do for 0.6pre1
 
-- fix an OPLL/OPL fixed drum freq regression caused by full linear pitch
 - piano/input pad
   - note input via piano
   - input pad
diff --git a/src/engine/platform/opl.cpp b/src/engine/platform/opl.cpp
index 949d104b8..e76d033f4 100644
--- a/src/engine/platform/opl.cpp
+++ b/src/engine/platform/opl.cpp
@@ -595,6 +595,7 @@ void DivPlatformOPL::tick(bool sysTick) {
   for (int i=0; i<totalChans; i++) {
     if (chan[i].freqChanged) {
       chan[i].freq=parent->calcFreq(chan[i].baseFreq,chan[i].pitch,false,octave(chan[i].baseFreq),chan[i].pitch2,chipClock,CHIP_FREQBASE);
+      if (chan[i].fixedFreq>0) chan[i].freq=chan[i].fixedFreq;
       if (chan[i].freq>131071) chan[i].freq=131071;
       int freqt=toFreq(chan[i].freq)+chan[i].pitch2;
       chan[i].freqH=freqt>>8;
@@ -844,16 +845,18 @@ int DivPlatformOPL::dispatch(DivCommand c) {
       if (c.value!=DIV_NOTE_NULL) {
         if (c.chan>=melodicChans && chan[c.chan].state.opllPreset==16 && chan[c.chan].state.fixedDrums) { // drums
           if (c.chan==melodicChans) {
-            chan[c.chan].baseFreq=(chan[c.chan].state.kickFreq&1023)<<(chan[c.chan].state.kickFreq>>10);
+            chan[c.chan].fixedFreq=(chan[c.chan].state.kickFreq&1023)<<(chan[c.chan].state.kickFreq>>10);
           } else if (c.chan==melodicChans+1 || c.chan==melodicChans+4) {
-            chan[c.chan].baseFreq=(chan[c.chan].state.snareHatFreq&1023)<<(chan[c.chan].state.snareHatFreq>>10);
+            chan[c.chan].fixedFreq=(chan[c.chan].state.snareHatFreq&1023)<<(chan[c.chan].state.snareHatFreq>>10);
           } else if (c.chan==melodicChans+2 || c.chan==melodicChans+3) {
-            chan[c.chan].baseFreq=(chan[c.chan].state.tomTopFreq&1023)<<(chan[c.chan].state.tomTopFreq>>10);
+            chan[c.chan].fixedFreq=(chan[c.chan].state.tomTopFreq&1023)<<(chan[c.chan].state.tomTopFreq>>10);
           } else {
             chan[c.chan].baseFreq=NOTE_FREQUENCY(c.value);
+            chan[c.chan].fixedFreq=0;
           }
         } else {
           chan[c.chan].baseFreq=NOTE_FREQUENCY(c.value);
+          chan[c.chan].fixedFreq=0;
         }
         chan[c.chan].note=c.value;
         chan[c.chan].freqChanged=true;
diff --git a/src/engine/platform/opl.h b/src/engine/platform/opl.h
index a67d50380..61ea46481 100644
--- a/src/engine/platform/opl.h
+++ b/src/engine/platform/opl.h
@@ -40,7 +40,7 @@ class DivPlatformOPL: public DivDispatch {
       DivInstrumentFM state;
       DivMacroInt std;
       unsigned char freqH, freqL;
-      int freq, baseFreq, pitch, pitch2, note, ins, sample;
+      int freq, baseFreq, pitch, pitch2, note, ins, sample, fixedFreq;
       bool active, insChanged, freqChanged, keyOn, keyOff, portaPause, furnacePCM, inPorta, fourOp, hardReset;
       int vol, outVol;
       unsigned char pan;
@@ -58,6 +58,7 @@ class DivPlatformOPL: public DivDispatch {
         note(0),
         ins(-1),
         sample(-1),
+        fixedFreq(0),
         active(false),
         insChanged(true),
         freqChanged(false),