GUI: add "create wave from selection" option

in sample editor

src/gui/doAction.cpp

@@ -1295,6 +1295,32 @@ void FurnaceGUI::doAction(int what) {
       MARK_MODIFIED;
       break;
     }
+    case GUI_ACTION_SAMPLE_CREATE_WAVE: {
+      if (curSample<0 || curSample>=(int)e->song.sample.size()) break;
+      DivSample* sample=e->song.sample[curSample];
+      SAMPLE_OP_BEGIN;
+      if (end-start<1) {
+        showError("select at least one sample!");
+      } else if (end-start>256) {
+        showError("maximum size is 256 samples!");
+      } else {
+        curWave=e->addWave();
+        if (curWave==-1) {
+          showError("too many wavetables!");
+        } else {
+          DivWavetable* wave=e->song.wave[curWave];
+          wave->min=0;
+          wave->max=255;
+          wave->len=end-start;
+          for (unsigned int i=start; i<end; i++) {
+            wave->data[i-start]=(sample->data8[i]&0xff)^0x80;
+          }
+          nextWindow=GUI_WINDOW_WAVE_EDIT;
+          MARK_MODIFIED;
+        }
+      }
+      break;
+    }
 
     case GUI_ACTION_ORDERS_UP:
       if (curOrder>0) {

src/gui/gui.h

@@ -525,6 +525,7 @@ enum FurnaceGUIActions {
   GUI_ACTION_SAMPLE_ZOOM_AUTO,
   GUI_ACTION_SAMPLE_MAKE_INS,
   GUI_ACTION_SAMPLE_SET_LOOP,
+  GUI_ACTION_SAMPLE_CREATE_WAVE,
   GUI_ACTION_SAMPLE_MAX,
 
   GUI_ACTION_ORDERS_MIN,

src/gui/guiConst.cpp

@@ -641,6 +641,7 @@ const FurnaceGUIActionDef guiActions[GUI_ACTION_MAX]={
   D("SAMPLE_ZOOM_AUTO", "Toggle auto-zoom", FURKMOD_CMD|SDLK_0),
   D("SAMPLE_MAKE_INS", "Create instrument from sample", 0),
   D("SAMPLE_SET_LOOP", "Set loop to selection", FURKMOD_CMD|SDLK_l),
+  D("SAMPLE_CREATE_WAVE", "Create wavetable from selection", FURKMOD_CMD|SDLK_w),
   D("SAMPLE_MAX", "", NOT_AN_ACTION),
 
   D("ORDERS_MIN", "---Orders", NOT_AN_ACTION),

src/gui/sampleEdit.cpp

@@ -1293,6 +1293,9 @@ void FurnaceGUI::drawSampleEdit() {
           if (ImGui::MenuItem("set loop to selection",BIND_FOR(GUI_ACTION_SAMPLE_SET_LOOP))) {
             doAction(GUI_ACTION_SAMPLE_SET_LOOP);
           }
+          if (ImGui::MenuItem("create wavetable from selection",BIND_FOR(GUI_ACTION_SAMPLE_CREATE_WAVE))) {
+            doAction(GUI_ACTION_SAMPLE_CREATE_WAVE);
+          }
           ImGui::EndPopup();
         }