prepare for wavetable synth

CMakeLists.txt

@@ -302,6 +302,7 @@ src/engine/sample.cpp
 src/engine/song.cpp
 src/engine/sysDef.cpp
 src/engine/wavetable.cpp
+src/engine/waveSynth.cpp
 src/engine/vgmOps.cpp
 src/engine/platform/abstract.cpp
 src/engine/platform/genesis.cpp

src/engine/instrument.h

@@ -477,6 +477,47 @@ struct DivInstrumentFDS {
   }
 };
 
+enum DivWaveSynthEffects {
+  DIV_WS_NONE=0,
+  // one waveform effects
+  DIV_WS_INVERT,
+  DIV_WS_ADD,
+  DIV_WS_SUBTRACT,
+  DIV_WS_AVERAGE,
+  DIV_WS_PHASE,
+  // two waveform effects
+  DIV_WS_NONE_DUAL=128,
+  DIV_WS_WIPE,
+  DIV_WS_FADE,
+  DIV_WS_PING_PONG,
+  DIV_WS_OVERLAY,
+  DIV_WS_NEGATIVE_OVERLAY,
+  DIV_WS_PHASE_DUAL,
+};
+
+struct DivInstrumentWaveSynth {
+  int wave1, wave2;
+  unsigned char rateDivider, width, height;
+  DivWaveSynthEffects effect;
+  bool oneShot, enabled, global;
+  unsigned char speed, param1, param2, param3, param4;
+  DivInstrumentWaveSynth():
+    wave1(0),
+    wave2(0),
+    rateDivider(1),
+    width(32),
+    height(32),
+    effect(DIV_WS_NONE),
+    oneShot(false),
+    enabled(false),
+    global(false),
+    speed(1),
+    param1(0),
+    param2(0),
+    param3(0),
+    param4(0) {}
+};
+
 struct DivInstrument {
   String name;
   bool mode;
@@ -488,6 +529,7 @@ struct DivInstrument {
   DivInstrumentAmiga amiga;
   DivInstrumentN163 n163;
   DivInstrumentFDS fds;
+  DivInstrumentWaveSynth ws;
   
   /**
    * save the instrument to a SafeWriter.

src/engine/waveSynth.cpp

@@ -0,0 +1,5 @@
+#include "waveSynth.h"
+
+bool DivWaveSynth::tick() {
+  return false;
+}

src/engine/waveSynth.h

@@ -0,0 +1,46 @@
+/**
+ * Furnace Tracker - multi-system chiptune tracker
+ * Copyright (C) 2021-2022 tildearrow and contributors
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#ifndef _WAVESYNTH_H
+#define _WAVESYNTH_H
+
+#include "instrument.h"
+#include "wavetable.h"
+
+class DivWaveSynth {
+  DivInstrument* ins;
+  int pos, stage, divCounter;
+  int output[256];
+  public:
+    /**
+     * tick this DivWaveSynth.
+     * @return whether the wave has changed.
+     */
+    bool tick();
+    void init(DivInstrument* ins);
+    DivWaveSynth():
+      ins(NULL),
+      pos(0),
+      stage(0),
+      divCounter(0) {
+      memset(output,0,sizeof(int)*256);
+    }
+};
+
+#endif