OPLL: implement fixed freq mode for drums

issue #249

papers/format.md

@@ -29,6 +29,7 @@ furthermore, an `or reserved` indicates this field is always present, but is res
 
 the format versions are:
 
+- 63: Furnace dev63
 - 62: Furnace dev62
 - 61: Furnace dev61
 - 60: Furnace dev60
@@ -476,6 +477,12 @@ size | description
  1?? | VIB macro
  1?? | WS macro
  1?? | KSR macro
+ --- | **OPL drums mode data** (>=63)
+  1  | fixed frequency mode
+  1  | reserved
+  2  | kick frequency
+  2  | snare/hi-hat frequency
+  2  | tom/top frequency
 ```
 
 # wavetable

src/engine/engine.h

@@ -37,8 +37,8 @@
     warnings+=(String("\n")+x); \
   }
 
-#define DIV_VERSION "dev62"
+#define DIV_VERSION "dev63"
-#define DIV_ENGINE_VERSION 62
+#define DIV_ENGINE_VERSION 63
 
 enum DivStatusView {
   DIV_STATUS_NOTHING=0,

src/engine/instrument.cpp

@@ -371,6 +371,13 @@ void DivInstrument::putInsData(SafeWriter* w) {
       w->writeC(op.ksrMacro[j]);
     }
   }
+
+  // OPL drum data
+  w->writeC(fm.fixedDrums);
+  w->writeC(0); // reserved
+  w->writeS(fm.kickFreq);
+  w->writeS(fm.snareHatFreq);
+  w->writeS(fm.tomTopFreq);
 }
 
 DivDataErrors DivInstrument::readInsData(SafeReader& reader, short version) {
@@ -694,6 +701,15 @@ DivDataErrors DivInstrument::readInsData(SafeReader& reader, short version) {
     }
   }
 
+  // OPL drum data
+  if (version>=63) {
+    fm.fixedDrums=reader.readC();
+    reader.readC(); // reserved
+    fm.kickFreq=reader.readS();
+    fm.snareHatFreq=reader.readS();
+    fm.tomTopFreq=reader.readS();
+  }
+
   return DIV_DATA_SUCCESS;
 }
 

src/engine/instrument.h

@@ -67,6 +67,8 @@ enum DivInstrumentType {
 
 struct DivInstrumentFM {
   unsigned char alg, fb, fms, ams, ops, opllPreset;
+  bool fixedDrums;
+  unsigned short kickFreq, snareHatFreq, tomTopFreq;
   struct Operator {
     unsigned char am, ar, dr, mult, rr, sl, tl, dt2, rs, dt, d2r, ssgEnv;
     unsigned char dam, dvb, egt, ksl, sus, vib, ws, ksr; // YMU759/OPL/OPZ
@@ -98,7 +100,11 @@ struct DivInstrumentFM {
     fms(0),
     ams(0),
     ops(4),
-    opllPreset(0) {
+    opllPreset(0),
+    fixedDrums(false),
+    kickFreq(0x520),
+    snareHatFreq(0x550),
+    tomTopFreq(0x1c0) {
     // default instrument
     fb=4;
     op[0].tl=42;

src/engine/platform/opll.cpp

@@ -377,7 +377,24 @@ int DivPlatformOPLL::dispatch(DivCommand c) {
       if (c.chan>=6 && properDrums) { // drums mode
         chan[c.chan].insChanged=false;
         if (c.value!=DIV_NOTE_NULL) {
-          chan[c.chan].baseFreq=NOTE_FREQUENCY(c.value);
+          if (chan[c.chan].state.opllPreset==16 && chan[c.chan].state.fixedDrums) {
+            switch (c.chan) {
+              case 6:
+                chan[c.chan].baseFreq=(chan[c.chan].state.kickFreq&511)<<(chan[c.chan].state.kickFreq>>9);
+                break;
+              case 7: case 10:
+                chan[c.chan].baseFreq=(chan[c.chan].state.snareHatFreq&511)<<(chan[c.chan].state.snareHatFreq>>9);
+                break;
+              case 8: case 9:
+                chan[c.chan].baseFreq=(chan[c.chan].state.tomTopFreq&511)<<(chan[c.chan].state.tomTopFreq>>9);
+                break;
+              default:
+                chan[c.chan].baseFreq=NOTE_FREQUENCY(c.value);
+                break;
+            }
+          } else {
+            chan[c.chan].baseFreq=NOTE_FREQUENCY(c.value);
+          }
           chan[c.chan].note=c.value;
           chan[c.chan].freqChanged=true;
         }

src/gui/insEdit.cpp

@@ -81,7 +81,7 @@ const char* opllInsNames[17]={
   "Synth Bass",
   "Acoustic Bass",
   "Electric Guitar",
-  "Drums (compatibility only!)"
+  "Drums"
 };
 
 enum FMParams {
@@ -857,7 +857,78 @@ void FurnaceGUI::drawInsEdit() {
             }
 
             if (ins->type==DIV_INS_OPLL && ins->fm.opllPreset==16) {
-              ImGui::Text("the Drums patch is only there for compatibility.\nit is highly encouraged you use the OPLL (drums) system instead!");
+              P(ImGui::Checkbox("Fixed frequency mode",&ins->fm.fixedDrums));
+              if (ImGui::IsItemHovered()) {
+                ImGui::SetTooltip("when enabled, drums will be set to the specified frequencies, ignoring the note.");
+              }
+              if (ins->fm.fixedDrums) {
+                int block=0;
+                int fNum=0;
+                if (ImGui::BeginTable("fixedDrumSettings",3)) {
+                  ImGui::TableNextRow(ImGuiTableRowFlags_Headers);
+                  ImGui::TableNextColumn();
+                  ImGui::Text("Drum");
+                  ImGui::TableNextColumn();
+                  ImGui::Text("Block");
+                  ImGui::TableNextColumn();
+                  ImGui::Text("FreqNum");
+
+                  ImGui::TableNextRow();
+                  ImGui::TableNextColumn();
+                  block=(ins->fm.kickFreq>>9)&7;
+                  fNum=ins->fm.kickFreq&511;
+                  ImGui::Text("Kick");
+                  ImGui::TableNextColumn();
+                  if (ImGui::InputInt("##DBlock0",&block,1,1)) {
+                    if (block<0) block=0;
+                    if (block>7) block=7;
+                    ins->fm.kickFreq=(block<<9)|fNum;
+                  }
+                  ImGui::TableNextColumn();
+                  if (ImGui::InputInt("##DFreq0",&fNum,1,1)) {
+                    if (fNum<0) fNum=0;
+                    if (fNum>511) fNum=511;
+                    ins->fm.kickFreq=(block<<9)|fNum;
+                  }
+
+                  ImGui::TableNextRow();
+                  ImGui::TableNextColumn();
+                  block=(ins->fm.snareHatFreq>>9)&7;
+                  fNum=ins->fm.snareHatFreq&511;
+                  ImGui::Text("Snare/Hi-hat");
+                  ImGui::TableNextColumn();
+                  if (ImGui::InputInt("##DBlock1",&block,1,1)) {
+                    if (block<0) block=0;
+                    if (block>7) block=7;
+                    ins->fm.snareHatFreq=(block<<9)|fNum;
+                  }
+                  ImGui::TableNextColumn();
+                  if (ImGui::InputInt("##DFreq1",&fNum,1,1)) {
+                    if (fNum<0) fNum=0;
+                    if (fNum>511) fNum=511;
+                    ins->fm.snareHatFreq=(block<<9)|fNum;
+                  }
+
+                  ImGui::TableNextRow();
+                  ImGui::TableNextColumn();
+                  block=(ins->fm.tomTopFreq>>9)&7;
+                  fNum=ins->fm.tomTopFreq&511;
+                  ImGui::Text("Tom/Top");
+                  ImGui::TableNextColumn();
+                  if (ImGui::InputInt("##DBlock2",&block,1,1)) {
+                    if (block<0) block=0;
+                    if (block>7) block=7;
+                    ins->fm.tomTopFreq=(block<<9)|fNum;
+                  }
+                  ImGui::TableNextColumn();
+                  if (ImGui::InputInt("##DFreq2",&fNum,1,1)) {
+                    if (fNum<0) fNum=0;
+                    if (fNum>511) fNum=511;
+                    ins->fm.tomTopFreq=(block<<9)|fNum;
+                  }
+                  ImGui::EndTable();
+                }
+              }
             }
 
             bool willDisplayOps=true;