Persistent canvas for subprograms

examples/sp_getput.rf

@@ -0,0 +1,3 @@
+>  v
+v  _  "a" 51 p R
+> 51g R

examples/submodule_add.rf

@@ -1,3 +1,3 @@
 >              v
-v P "A"0"add"0 <  Load ::add, call it l.
+v P "A"0"add"0 <  Load ::add, call it A
 > 2 2 A . 25*, @

examples/submodule_getput.rf

@@ -0,0 +1,3 @@
+>                    v
+v P "A"0"sp_getput"0 <  Load ::sp_getput, call it l.
+> A 1 A , 25*, @

examples/submodule_getput.rf.txt

@@ -0,0 +1 @@
+a

specification.md

@@ -94,6 +94,11 @@ For example, to pass "hello" as a parameter would be:
 |   R    | rtn  | Return to caller                       |
 |   L    | lock | Hide the stack before a certain cell - use to stop bugs overwriting previous program's stack elements. |
 
+Calling P will load the subprogram's canvas into memory. Any changes to the Canvas
+in one subprogram call will be kept and seen by the next.
+
+See submodule_getput.rf which calls sp_getput.rf
+
 ### Examples
 
 ```

src/rufunge.cpp

@@ -265,7 +265,10 @@ public:
 		char y = th->pop();
 		char x = th->pop();
 		Canvas *c = th->cursor->canvas;
-		th->push(c->get(x, y));
+		char v = c->get(x, y);
+		th->push(v);
+
+		std::cerr << "Got " << v << " from " << (int)x << ", " << (int)y << std::endl;
 
 		th->move();
 	}
@@ -281,6 +284,7 @@ public:
 		char v = th->pop();
 		Canvas *c = th->cursor->canvas;
 		c->set(x, y, v);
+		std::cerr << "Put " << v << " to " << (int)x << ", " << (int)y << std::endl;
 
 		th->move();
 	}
@@ -321,25 +325,18 @@ public:
 class StartRufungeSR : public Subroutine
 {
 public:
+	Canvas *canvas = new Canvas();
 	std::string module;
 	std::string file;
 	virtual void run(VM *vm, Thread *th)
 	{
-		Canvas *d = new Canvas();
 		std::string filepath = std::string("examples/") + file + ".rf";
-		if (d->readFromFile(filepath.c_str())) {
-			std::cerr << "Loaded " << filepath << std::endl;
-		} else {
-			std::cerr << "Error! Unable to load SR "
-				<< module << "::" << file << std::endl;
-			th->state = ETS_DEAD;
-			return;
-		}
+		std::cerr << "Entering " << filepath << std::endl;
 
 		th->move();
 
 		Cursor *cursor = new Cursor();
-		cursor->canvas = d;
+		cursor->canvas = canvas;
 		th->pushCursor(cursor);
 		vm->assignStandardSR(th);
 	}
@@ -369,10 +366,23 @@ public:
 			c = th->pop();
 		}
 
+		// Load canvas
+		Canvas *d = new Canvas();
+		std::string filepath = std::string("examples/") + file + ".rf";
+		if (d->readFromFile(filepath.c_str())) {
+			std::cerr << "Loaded " << filepath << std::endl;
+		} else {
+			std::cerr << "Error! Unable to load SR "
+				<< module << "::" << file << std::endl;
+			th->state = ETS_DEAD;
+			return;
+		}
+
 		// Load as operator
 		StartRufungeSR *sr = new StartRufungeSR;
 		sr->module = module;
 		sr->file = file;
+		sr->canvas = d;
 		th->cursor->operators[op] = vm->loadSubroutine(sr);
 		std::cerr << "Loaded rufunge operator " << op << " to be "
 			<< module << "::" << file << std::endl;