- deconstruct A_Jump with multiple labels into A_Jump(chance, RandomPick(label1, label2, label3,...)) to remove this ugly special case from the VM calling convention.

This also adds the number of available choices to OP_IJMP.

src/p_actionfunctions.cpp

@@ -75,7 +75,6 @@ AActor *SingleActorFromTID(int tid, AActor *defactor);
 
 static FRandom pr_camissile ("CustomActorfire");
 static FRandom pr_cabullet ("CustomBullet");
-static FRandom pr_cajump ("CustomJump");
 static FRandom pr_cwbullet ("CustomWpBullet");
 static FRandom pr_cwjump ("CustomWpJump");
 static FRandom pr_cwpunch ("CustomWpPunch");
@@ -87,6 +86,7 @@ static FRandom pr_burst ("Burst");
 static FRandom pr_monsterrefire ("MonsterRefire");
 static FRandom pr_teleport("A_Teleport");
 static FRandom pr_bfgselfdamage("BFGSelfDamage");
+FRandom pr_cajump("CustomJump");
 
 //==========================================================================
 //
@@ -1129,13 +1129,10 @@ DEFINE_ACTION_FUNCTION(AActor, A_Jump)
 {
 	PARAM_ACTION_PROLOGUE(AActor);
 	PARAM_INT(maxchance);
+	PARAM_STATE_ACTION(jumpto);
 
-	paramnum++;		// Increment paramnum to point at the first jump target
-	int count = numparam - paramnum;
-	if (count > 0 && (maxchance >= 256 || pr_cajump() < maxchance))
+	if (maxchance >= 256 || pr_cajump() < maxchance)
 	{
-		int jumpnum = (count == 1 ? 0 : (pr_cajump() % count));
-		PARAM_STATE_ACTION_AT(paramnum + jumpnum, jumpto);
 		ACTION_RETURN_STATE(jumpto);
 	}
 	ACTION_RETURN_STATE(NULL);

src/scripting/backend/codegen.cpp

@@ -5660,7 +5660,7 @@ ExpEmit FxRandomPick::Emit(VMFunctionBuilder *build)
 
 	ExpEmit resultreg(build, REGT_INT);
 	build->Emit(OP_RESULT, 0, REGT_INT, resultreg.RegNum);
-	build->Emit(OP_IJMP, resultreg.RegNum, 0);
+	build->Emit(OP_IJMP, resultreg.RegNum, choices.Size());
 
 	// Free the result register now. The simple code generation algorithm should
 	// automatically pick it as the destination register for each case.
@@ -8781,6 +8781,41 @@ VMFunction *FxVMFunctionCall::GetDirectFunction(PFunction *callingfunc, const Ve
 	return nullptr;
 }
 
+//==========================================================================
+//
+// FxVMFunctionCall :: UnravelVarArgAJump
+//
+// Converts A_Jump(chance, a, b, c, d) -> A_Jump(chance, RandomPick[cajump](a, b, c, d))
+// so that varargs are restricted to either text formatting or graphics drawing.
+//
+//==========================================================================
+extern FRandom pr_cajump;
+
+bool FxVMFunctionCall::UnravelVarArgAJump(FCompileContext &ctx)
+{
+	FArgumentList rplist;
+
+	for (unsigned i = 1; i < ArgList.Size(); i++)
+	{
+		// This needs a bit of casting voodoo because RandomPick wants integer parameters.
+		auto x = new FxIntCast(new FxTypeCast(ArgList[i], TypeStateLabel, true, true), true, true);
+		rplist.Push(x->Resolve(ctx));
+		ArgList[i] = nullptr;
+		if (rplist[i - 1] == nullptr)
+		{
+			return false;
+		}
+	}
+	FxExpression *x = new FxRandomPick(&pr_cajump, rplist, false, ScriptPosition, true);
+	x = x->Resolve(ctx);
+	// This cannot be done with a cast because that interprets the value as an index.
+	// All we want here is to take the literal value and change its type.
+	if (x) x->ValueType = TypeStateLabel;	
+	ArgList[1] = x;
+	ArgList.Clamp(2);
+	return x != nullptr;
+}
+
 //==========================================================================
 //
 // FxVMFunctionCall :: Resolve
@@ -8813,9 +8848,18 @@ FxExpression *FxVMFunctionCall::Resolve(FCompileContext& ctx)
 		return nullptr;
 	}
 
-	if (Function->Variants[0].Implementation->PrintableName.CompareNoCase("CustomStatusBar.DrawTexture") == 0)
+	// Unfortunately the PrintableName is the only safe thing to catch this special case here.
+	if (Function->Variants[0].Implementation->PrintableName.CompareNoCase("Actor.A_Jump [Native]") == 0)
 	{
-		int a = 0;
+		// Unravel the varargs part of this function here so that the VM->native interface does not have to deal with it anymore.
+		if (ArgList.Size() > 2)
+		{
+			auto ret = UnravelVarArgAJump(ctx);
+			if (!ret)
+			{
+				return nullptr;
+			}
+		}
 	}
 
 	CallingFunction = ctx.Function;

src/scripting/backend/codegen.h

@@ -1764,6 +1764,7 @@ class FxVMFunctionCall : public FxExpression
 	PFunction *CallingFunction;
 
 	bool CheckAccessibility(const VersionInfo &ver);
+	bool UnravelVarArgAJump(FCompileContext&);
 
 public:
 	FxVMFunctionCall(FxExpression *self, PFunction *func, FArgumentList &args, const FScriptPosition &pos, bool novirtual);

wadsrc/static/zscript/actor.txt

@@ -1062,7 +1062,7 @@ class Actor : Thinker native
 	deprecated("2.3") native void A_PlaySoundEx(sound whattoplay, name slot, bool looping = false, int attenuation = 0);
 	deprecated("2.3") native void A_StopSoundEx(name slot);
 	native void A_SeekerMissile(int threshold, int turnmax, int flags = 0, int chance = 50, int distance = 10);
-	native action state A_Jump(int chance, statelabel label, ...);
+	native action state A_Jump(int chance, statelabel label);
 	native Actor A_SpawnProjectile(class<Actor> missiletype, double spawnheight = 32, double spawnofs_xy = 0, double angle = 0, int flags = 0, double pitch = 0, int ptr = AAPTR_TARGET);
 	native void A_CustomBulletAttack(double spread_xy, double spread_z, int numbullets, int damageperbullet, class<Actor> pufftype = "BulletPuff", double range = 0, int flags = 0, int ptr = AAPTR_TARGET, class<Actor> missile = null, double Spawnheight = 32, double Spawnofs_xy = 0);
 	native void A_CustomRailgun(int damage, int spawnofs_xy = 0, color color1 = 0, color color2 = 0, int flags = 0, int aim = 0, double maxdiff = 0, class<Actor> pufftype = "BulletPuff", double spread_xy = 0, double spread_z = 0, double range = 0, int duration = 0, double sparsity = 1.0, double driftspeed = 1.0, class<Actor> spawnclass = null, double spawnofs_z = 0, int spiraloffset = 270, int limit = 0, double veleffect = 3);