From 1921fd17595efa7ce7ed8212c33417bd031919a6 Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Sat, 30 Jul 2022 01:00:51 -0500
Subject: [PATCH] PCE: implement anti-click technology

---
 src/engine/platform/pce.cpp | 12 +++++++++++-
 src/engine/platform/pce.h   |  5 ++++-
 src/gui/sysConf.cpp         | 19 ++++++++++++++++++-
 3 files changed, 33 insertions(+), 3 deletions(-)

diff --git a/src/engine/platform/pce.cpp b/src/engine/platform/pce.cpp
index f1eb5a10..a61b6183 100644
--- a/src/engine/platform/pce.cpp
+++ b/src/engine/platform/pce.cpp
@@ -136,8 +136,9 @@ void DivPlatformPCE::updateWave(int ch) {
   chWrite(ch,0x04,0x5f);
   chWrite(ch,0x04,0x1f);
   for (int i=0; i<32; i++) {
-    chWrite(ch,0x06,chan[ch].ws.output[i]);
+    chWrite(ch,0x06,chan[ch].ws.output[(i+chan[ch].antiClickWavePos)&31]);
   }
+  chan[ch].antiClickWavePos&=31;
   if (chan[ch].active) {
     chWrite(ch,0x04,0x80|chan[ch].outVol);
   }
@@ -150,6 +151,13 @@ static unsigned char noiseFreq[12]={
 
 void DivPlatformPCE::tick(bool sysTick) {
   for (int i=0; i<6; i++) {
+    // anti-click
+    if (antiClickEnabled && sysTick && chan[i].freq>0) {
+      chan[i].antiClickPeriodCount+=(chipClock/MAX(parent->getCurHz(),1.0f));
+      chan[i].antiClickWavePos+=chan[i].antiClickPeriodCount/chan[i].freq;
+      chan[i].antiClickPeriodCount%=chan[i].freq;
+    }
+
     chan[i].std.next();
     if (chan[i].std.vol.had) {
       chan[i].outVol=VOL_SCALE_LOG(chan[i].vol&31,MIN(31,chan[i].std.vol.val),31);
@@ -555,6 +563,8 @@ void DivPlatformPCE::setFlags(unsigned int flags) {
   } else {
     chipClock=COLOR_NTSC;
   }
+  // flags&4 will be chip revision
+  antiClickEnabled=!(flags&8);
   rate=chipClock/12;
   for (int i=0; i<6; i++) {
     oscBuf[i]->rate=rate;
diff --git a/src/engine/platform/pce.h b/src/engine/platform/pce.h
index 870b5218..22a24ddf 100644
--- a/src/engine/platform/pce.h
+++ b/src/engine/platform/pce.h
@@ -28,7 +28,7 @@
 
 class DivPlatformPCE: public DivDispatch {
   struct Channel {
-    int freq, baseFreq, pitch, pitch2, note;
+    int freq, baseFreq, pitch, pitch2, note, antiClickPeriodCount, antiClickWavePos;
     int dacPeriod, dacRate;
     unsigned int dacPos;
     int dacSample, ins;
@@ -47,6 +47,8 @@ class DivPlatformPCE: public DivDispatch {
       pitch(0),
       pitch2(0),
       note(0),
+      antiClickPeriodCount(0),
+      antiClickWavePos(0),
       dacPeriod(0),
       dacRate(0),
       dacPos(0),
@@ -69,6 +71,7 @@ class DivPlatformPCE: public DivDispatch {
   Channel chan[6];
   DivDispatchOscBuffer* oscBuf[6];
   bool isMuted[6];
+  bool antiClickEnabled;
   struct QueuedWrite {
       unsigned char addr;
       unsigned char val;
diff --git a/src/gui/sysConf.cpp b/src/gui/sysConf.cpp
index e5407486..36531242 100644
--- a/src/gui/sysConf.cpp
+++ b/src/gui/sysConf.cpp
@@ -109,6 +109,24 @@ void FurnaceGUI::drawSysConf(int chan, DivSystem type, unsigned int& flags, bool
       }
       break;
     }
+    case DIV_SYSTEM_PCE: {
+      sysPal=flags&1;
+      if (ImGui::Checkbox("Pseudo-PAL",&sysPal)) {
+        copyOfFlags=(flags&(~1))|(unsigned int)sysPal;
+      }
+      bool antiClick=flags&8;
+      if (ImGui::Checkbox("Disable anti-click",&antiClick)) {
+        copyOfFlags=(flags&(~8))|(antiClick<<3);
+      }
+      break;
+    }
+    case DIV_SYSTEM_GB: {
+      bool antiClick=flags&8;
+      if (ImGui::Checkbox("Disable anti-click",&antiClick)) {
+        copyOfFlags=(flags&(~8))|(antiClick<<3);
+      }
+      break;
+    }
     case DIV_SYSTEM_OPLL:
     case DIV_SYSTEM_OPLL_DRUMS:
     case DIV_SYSTEM_VRC7: {
@@ -631,7 +649,6 @@ void FurnaceGUI::drawSysConf(int chan, DivSystem type, unsigned int& flags, bool
       }
       break;
     }
-    case DIV_SYSTEM_GB:
     case DIV_SYSTEM_SWAN:
     case DIV_SYSTEM_VERA:
     case DIV_SYSTEM_BUBSYS_WSG: