Allow M99 to return a named variable and value

Implements #1038

Signed-off-by: Ben Agricola <[email protected]>

Author: benagricola

src/GCodes/GCodes.cpp

@@ -3437,6 +3437,24 @@ bool GCodes::GetMacroRestarted() const noexcept
 	return ms.doingFileMacro && ms.GetPrevious() != nullptr && ms.GetPrevious()->firstCommandAfterRestart;
 }
 
+void GCodes::FileMacroReturnValue(GCodeBuffer& gb, const StringRef& varName, ExpressionValue& returnValue) noexcept
+{
+	if (gb.IsDoingFileMacro() && gb.GetStackDepth() > 0)
+	{
+		GCodeMachineState * const ps = gb.CurrentFileMachineState().GetPrevious();
+		auto vset = WriteLockedPointer<VariableSet>(nullptr, &ps->variables);
+		Variable *_ecv_null v = vset->Lookup(varName.c_str(), false);
+		if (v == nullptr)
+		{
+			vset->InsertNew(varName.c_str(), returnValue, ps->GetBlockNesting());
+		}
+		else
+		{
+			v->Assign(returnValue);
+		}
+	}
+}
+
 void GCodes::FileMacroCyclesReturn(GCodeBuffer& gb) noexcept
 {
 	//const int retValue = (gb.Seen('P')) ? gb.GetIValue() : 0;		// for when we allow M99 to return 'result'

src/GCodes/GCodes.h

@@ -385,7 +385,8 @@ class GCodes
 	bool DoFileMacro(GCodeBuffer& gb, const char *_ecv_array fileName, bool reportMissing, int codeRunning) noexcept;	// Run a GCode macro file, optionally report error if not found
 	bool DoFileMacroWithParameters(GCodeBuffer& gb, const char *_ecv_array fileName, bool reportMissing, int codeRunning) THROWS(GCodeException);
 
-	void FileMacroCyclesReturn(GCodeBuffer& gb) noexcept;								// End a macro
+	void FileMacroCyclesReturn(GCodeBuffer& gb) noexcept;														  // End a macro
+	void FileMacroReturnValue(GCodeBuffer& gb, const StringRef& varName, ExpressionValue& returnValue) noexcept; // Return a value from a macro
 
 	bool ActOnCode(GCodeBuffer& gb, const StringRef& reply) noexcept;					// Do a G, M or T Code
 	bool HandleGcode(GCodeBuffer& gb, const StringRef& reply) THROWS(GCodeException);	// Do a G code

src/GCodes/GCodes2.cpp

@@ -1675,8 +1675,19 @@ bool GCodes::HandleMcode(GCodeBuffer& gb, const StringRef& reply) THROWS(GCodeEx
 				break;
 
 			case 99: // Return from Macro/Subprogram
+			{
+				String<MaxVariableNameLength> varName;
+				bool seenV = false;
+				gb.TryGetQuotedString('V', varName.GetRef(), seenV, false);
+
+				if(seenV) {
+					ExpressionValue returnVar = (gb.Seen('R')) ? gb.GetExpression() : ExpressionValue();
+					FileMacroReturnValue(gb, varName.GetRef(), returnVar);
+				}
+
 				FileMacroCyclesReturn(gb);
 				break;
+			}
 
 			case 101: // Un-retract, generated by S3D if "Include M101/101/103" is enabled
 				result = RetractFilament(gb, false);