From 16dfc785d334bdc16da91b6b36d405ba979b9c65 Mon Sep 17 00:00:00 2001
From: tildearrow <tildearrow@protonmail.com>
Date: Sat, 5 Mar 2022 00:36:50 -0500
Subject: [PATCH] PC speaker: improvements

---
 src/engine/platform/pcspkr.cpp | 75 ++++++++++++++++++++++++++++++++--
 src/engine/platform/pcspkr.h   |  9 +++-
 src/engine/song.h              |  6 +++
 src/gui/gui.cpp                | 22 ++++++++++
 4 files changed, 107 insertions(+), 5 deletions(-)

diff --git a/src/engine/platform/pcspkr.cpp b/src/engine/platform/pcspkr.cpp
index 76d6612ab..51353fedf 100644
--- a/src/engine/platform/pcspkr.cpp
+++ b/src/engine/platform/pcspkr.cpp
@@ -37,7 +37,10 @@ const char* DivPlatformPCSpeaker::getEffectName(unsigned char effect) {
   return NULL;
 }
 
-void DivPlatformPCSpeaker::acquire(short* bufL, short* bufR, size_t start, size_t len) {
+const float cut=0.05;
+const float reso=0.06;
+
+void DivPlatformPCSpeaker::acquire_unfilt(short* bufL, short* bufR, size_t start, size_t len) {
   for (size_t i=start; i<start+len; i++) {
     if (on) {
       pos-=PCSPKR_DIVIDER;
@@ -45,17 +48,78 @@ void DivPlatformPCSpeaker::acquire(short* bufL, short* bufR, size_t start, size_
         if (freq<1) {
           pos=1;
         } else {
-          pos+=flip?(freq>>1):((freq+1)>>1);
+          pos+=freq;
         }
-        flip=!flip;
       }
-      bufL[i]=(flip && !isMuted[0])?32767:0;
+      bufL[i]=(pos>(freq>>1) && !isMuted[0])?32767:0;
     } else {
       bufL[i]=0;
     }
   }
 }
 
+void DivPlatformPCSpeaker::acquire_cone(short* bufL, short* bufR, size_t start, size_t len) {
+  for (size_t i=start; i<start+len; i++) {
+    if (on) {
+      pos-=PCSPKR_DIVIDER;
+      while (pos<0) {
+        if (freq<1) {
+          pos=1;
+        } else {
+          pos+=freq;
+        }
+      }
+      float next=(pos>((freq+16)>>1) && !isMuted[0])?1:0;
+      low+=0.04*band;
+      band+=0.04*(next-low-band);
+      float out=(low+band)*0.75;
+      if (out>1.0) out=1.0;
+      if (out<-1.0) out=-1.0;
+      bufL[i]=out*32767;
+    } else {
+      bufL[i]=0;
+    }
+  }
+}
+
+void DivPlatformPCSpeaker::acquire_piezo(short* bufL, short* bufR, size_t start, size_t len) {
+  for (size_t i=start; i<start+len; i++) {
+    if (on) {
+      pos-=PCSPKR_DIVIDER;
+      while (pos<0) {
+        if (freq<1) {
+          pos=1;
+        } else {
+          pos+=freq;
+        }
+      }
+      float next=(pos>((freq+64)>>1) && !isMuted[0])?1:0;
+      low+=cut*band;
+      band+=cut*(next-low-(reso*band));
+      float out=band*0.15-(next-low)*0.06;
+      if (out>1.0) out=1.0;
+      if (out<-1.0) out=-1.0;
+      bufL[i]=out*32767;
+    } else {
+      bufL[i]=0;
+    }
+  }
+}
+
+void DivPlatformPCSpeaker::acquire(short* bufL, short* bufR, size_t start, size_t len) {
+  switch (speakerType) {
+    case 0:
+      acquire_unfilt(bufL,bufR,start,len);
+      break;
+    case 1:
+      acquire_cone(bufL,bufR,start,len);
+      break;
+    case 2:
+      acquire_piezo(bufL,bufR,start,len);
+      break;
+  }
+}
+
 void DivPlatformPCSpeaker::tick() {
   for (int i=0; i<1; i++) {
     chan[i].std.next();
@@ -221,6 +285,8 @@ void DivPlatformPCSpeaker::reset() {
   freq=0;
   pos=0;
   flip=false;
+  low=0;
+  band=0;
 
   memset(regPool,0,2);
 }
@@ -232,6 +298,7 @@ bool DivPlatformPCSpeaker::keyOffAffectsArp(int ch) {
 void DivPlatformPCSpeaker::setFlags(unsigned int flags) {
   chipClock=COLOR_NTSC/3.0;
   rate=chipClock/PCSPKR_DIVIDER;
+  speakerType=flags&3;
 }
 
 void DivPlatformPCSpeaker::notifyInsDeletion(void* ins) {
diff --git a/src/engine/platform/pcspkr.h b/src/engine/platform/pcspkr.h
index 90e19b8ca..caf6b7f3a 100644
--- a/src/engine/platform/pcspkr.h
+++ b/src/engine/platform/pcspkr.h
@@ -53,12 +53,19 @@ class DivPlatformPCSpeaker: public DivDispatch {
   Channel chan[1];
   bool isMuted[1];
   bool on, flip;
-  int pos;
+  int pos, speakerType;
+  float low, band;
+  float low2, high2, band2;
+  float low3, band3;
   unsigned short freq;
   unsigned char regPool[2];
 
   friend void putDispatchChan(void*,int,int);
 
+  void acquire_unfilt(short* bufL, short* bufR, size_t start, size_t len);
+  void acquire_cone(short* bufL, short* bufR, size_t start, size_t len);
+  void acquire_piezo(short* bufL, short* bufR, size_t start, size_t len);
+
   public:
     void acquire(short* bufL, short* bufR, size_t start, size_t len);
     int dispatch(DivCommand c);
diff --git a/src/engine/song.h b/src/engine/song.h
index fff1065fe..d1e255d95 100644
--- a/src/engine/song.h
+++ b/src/engine/song.h
@@ -215,6 +215,12 @@ struct DivSong {
   //     - 1: Amiga 1200
   //   - bit 8-14: stereo separation
   //     - 0 is 0% while 127 is 100%
+  // - PC Speaker:
+  //   - bit 0-1: speaker type
+  //     - 0: unfiltered
+  //     - 1: cone
+  //     - 2: piezo
+  //     - 3: real (TODO)
   // - QSound:
   //   - bit 12-20: echo feedback
   //     - Valid values are 0-255
diff --git a/src/gui/gui.cpp b/src/gui/gui.cpp
index 7ee75fc4d..191f0c21f 100644
--- a/src/gui/gui.cpp
+++ b/src/gui/gui.cpp
@@ -4843,6 +4843,28 @@ bool FurnaceGUI::loop() {
                 }
                 break;
               }
+              case DIV_SYSTEM_PCSPKR: {
+                ImGui::Text("Speaker type:");
+                if (ImGui::RadioButton("Unfiltered",(flags&3)==0)) {
+                  e->setSysFlags(i,(flags&(~3))|0,restart);
+                  updateWindowTitle();
+                }
+                if (ImGui::RadioButton("Cone",(flags&3)==1)) {
+                  e->setSysFlags(i,(flags&(~3))|1,restart);
+                  updateWindowTitle();
+                }
+                if (ImGui::RadioButton("Piezo",(flags&3)==2)) {
+                  e->setSysFlags(i,(flags&(~3))|2,restart);
+                  updateWindowTitle();
+                }
+                /*
+                if (ImGui::RadioButton("Use system beeper",(flags&3)==3)) {
+                  e->setSysFlags(i,(flags&(~3))|3,restart);
+                  updateWindowTitle();
+                }
+                */
+                break;
+              }
               case DIV_SYSTEM_QSOUND: {
                 ImGui::Text("Echo delay:");
                 int echoBufSize=2725 - (flags & 4095);