From 4ed40d37d6c488ac17f5aeb7b92f72b25d356fa8 Mon Sep 17 00:00:00 2001
From: cam900 <dbtlrchl@naver.com>
Date: Wed, 27 Aug 2025 21:02:51 +0900
Subject: [PATCH] Add sample limit in OPL4 PCM, Reduce duplicate it has 512 (if
 header at 0x000000) or 128 (otherwise; first 384 sample is from bottommost
 area (ex: YRW801 ROM) in this case) sample limits

---
 src/engine/platform/opl.cpp | 31 ++++++++++++++++++++-----------
 1 file changed, 20 insertions(+), 11 deletions(-)

diff --git a/src/engine/platform/opl.cpp b/src/engine/platform/opl.cpp
index 762bde308..5a8f81a4e 100644
--- a/src/engine/platform/opl.cpp
+++ b/src/engine/platform/opl.cpp
@@ -37,6 +37,9 @@
 #define PCM_CHECK(ch) ((chipType==4) && (ch>=pcmChanOffs))
 #define PCM_REG(ch) (ch-pcmChanOffs)
 
+// check if PCM in RAM (and size is <= 2MB) - 4MB uses whole sample area
+#define PCM_IN_RAM (ramSize<=0x200000)
+
 // N = invalid
 #define N 255
 
@@ -1466,7 +1469,7 @@ void DivPlatformOPL::tick(bool sysTick) {
         ctrl|=(chan[i].active?0x80:0)|(chan[i].damp?0x40:0)|(chan[i].lfoReset?0x20:0)|(chan[i].ch?0x10:0)|(isMuted[i]?8:(chan[i].pan&0xf));
         int waveNum=chan[i].sample;
         if (waveNum>=0) {
-          if (ramSize<=0x200000) {
+          if (PCM_IN_RAM) {
             waveNum=CLAMP(waveNum,0,0x7f)|0x180;
           }
           if (chan[i].keyOn) {
@@ -2941,7 +2944,7 @@ void DivPlatformOPL::reset() {
     if (chipType==4) {
       immWrite(0x105,3);
       // Reset wavetable header
-      immWrite(0x202,(ramSize<=0x200000)?0x10:0x00);
+      immWrite(0x202,PCM_IN_RAM?0x10:0x00);
       // initialize mixer volume
       fmMixL=7;
       fmMixR=7;
@@ -3209,7 +3212,7 @@ void DivPlatformOPL::setFlags(const DivConfig& flags) {
       pcm.setClockFrequency(chipClock);
       rate=chipClock/768;
       chipRateBase=chipClock/684;
-      immWrite(0x202,(ramSize<=0x200000)?0x10:0x00);
+      immWrite(0x202,PCM_IN_RAM?0x10:0x00);
       break;
     case 759:
       rate=48000;
@@ -3232,7 +3235,7 @@ const void* DivPlatformOPL::getSampleMem(int index) {
 
 size_t DivPlatformOPL::getSampleMemCapacity(int index) {
   return (index==0 && pcmChanOffs>=0)?
-          ((ramSize<=0x200000)?0x200000+ramSize:ramSize):
+          (PCM_IN_RAM?0x200000+ramSize:ramSize):
           ((index==0 && adpcmChan>=0)?262144:0);
 }
 
@@ -3269,10 +3272,16 @@ void DivPlatformOPL::renderSamples(int sysID) {
   memCompo.name="Sample Memory";
 
   if (pcmChanOffs>=0) { // OPL4 PCM
-    size_t memPos=((ramSize<=0x200000)?0x200600:0x1800);
-    const int maxSample=(ramSize<=0x200000)?127:511;
+    size_t memPos=(PCM_IN_RAM?0x200600:0x1800);
+    const int maxSample=PCM_IN_RAM?128:512;
     int sampleCount=parent->song.sampleLen;
-    if (sampleCount>maxSample) sampleCount=maxSample;
+    if (sampleCount>maxSample) {
+      // mark the rest as unavailable
+      for (int i=maxSample; i<sampleCount; i++) {
+        sampleLoaded[i]=false;
+      }
+      sampleCount=maxSample;
+    }
     for (int i=0; i<sampleCount; i++) {
       DivSample* s=parent->song.sample[i];
       if (!s->renderOn[0][sysID]) {
@@ -3335,7 +3344,7 @@ void DivPlatformOPL::renderSamples(int sysID) {
     // instrument table
     for (int i=0; i<sampleCount; i++) {
       DivSample* s=parent->song.sample[i];
-      unsigned int insAddr=(i*12)+((ramSize<=0x200000)?0x200000:0);
+      unsigned int insAddr=(i*12)+(PCM_IN_RAM?0x200000:0);
       unsigned char bitDepth;
       int endPos=CLAMP(s->isLoopable()?s->loopEnd:(s->samples+1),1,0x10000);
       int loop=s->isLoopable()?CLAMP(s->loopStart,0,endPos-2):(endPos-2);
@@ -3366,12 +3375,12 @@ void DivPlatformOPL::renderSamples(int sysID) {
       pcmMem[6+insAddr]=(~(endPos-1))&0xff;
       // on MultiPCM this consists of instrument params, but on OPL4 this is not used
       pcmMem[7+insAddr]=0; // LFO, VIB
-      pcmMem[8+insAddr]=(0xf << 4) | (0xf << 0); // AR, D1R
+      pcmMem[8+insAddr]=(0xf<<4)|(0xf<<0); // AR, D1R
       pcmMem[9+insAddr]=0; // DL, D2R
-      pcmMem[10+insAddr]=(0xf << 4) | (0xf << 0); // RC, RR
+      pcmMem[10+insAddr]=(0xf<<4)|(0xf<<0); // RC, RR
       pcmMem[11+insAddr]=0; // AM
     }
-    if (ramSize<=0x200000) {
+    if (PCM_IN_RAM) {
       memCompo.entries.push_back(DivMemoryEntry(DIV_MEMORY_RESERVED,"ROM data",0,0,0x200000));
     }