fix: make SimpleFunction directory able to upload

projects/src/samples/vm/vm.ts

@@ -1,4 +1,4 @@
-export const SIMPLE_FUNCTION = `
+export const BRANCHING_FUNCTION = `
 // __implicit
   push constant 3
   push constant 4

simulator/src/vm/vm.test.ts

@@ -1,8 +1,9 @@
 import { unwrap } from "@davidsouther/jiffies/lib/esm/result.js";
+import { vm as SIMPLE_FUNCTION } from "@nand2tetris/projects/project_08/20_simple_function.js";
 import { FIBONACCI } from "@nand2tetris/projects/samples/vm/fibonnaci.js";
 import {
+  BRANCHING_FUNCTION,
   NESTED_FUNCTION,
-  SIMPLE_FUNCTION,
   STATIC,
 } from "@nand2tetris/projects/samples/vm/vm.js";
 import { VM } from "../languages/vm.js";
@@ -207,6 +208,20 @@ test("07 / Memory Access / Pointer Test", () => {
   expect(test).toEqual([6084, 3030, 3040, 32, 46]);
 });
 
+test("08 / Branching Function", () => {
+  const { instructions } = unwrap(VM.parse(BRANCHING_FUNCTION));
+  const vm = unwrap(Vm.build(instructions));
+
+  vm.write([]);
+
+  for (let i = 0; i < 100; i++) {
+    vm.step();
+  }
+
+  const test = vm.read([0, 256]);
+  expect(test).toEqual([257, 12]);
+});
+
 const LOOP_TEST = `
 push constant 0    
 pop local 0         // initializes sum = 0
@@ -309,18 +324,11 @@ test("08 / Program Flow / Fibonacci Series", () => {
   expect(test).toEqual([0, 1, 1, 2, 3, 5]);
 });
 
-test("08 / Simple Function / Simple Function", () => {
+test("08 / Functions / SimpleFunction", () => {
   const { instructions } = unwrap(VM.parse(SIMPLE_FUNCTION));
   const vm = unwrap(Vm.build(instructions));
 
-  vm.write([]);
-
-  for (let i = 0; i < 100; i++) {
-    vm.step();
-  }
-
-  const test = vm.read([0, 256]);
-  expect(test).toEqual([257, 12]);
+  expect(() => vm.vmStack()).not.toThrow("Assertion failed");
 });
 
 test("08 / Functions / NestedCall", () => {

simulator/src/vm/vm.ts

@@ -847,6 +847,7 @@ export class Vm {
       const nArg = this.segmentInitializations["argument"].n;
       const nLocal = this.segmentInitializations["local"].n;
       const nThis = this.invocation.thisN ?? 0;
+      const stackCount = frameEnd - stackBase;
       return {
         fn,
         args: {
@@ -861,8 +862,11 @@ export class Vm {
         },
         stack: {
           base: 256,
-          count: frameEnd - stackBase,
-          values: [...this.memory.map((_, v) => v, stackBase, frameEnd)],
+          count: Math.max(0, stackCount),
+          values:
+            stackCount > 0
+              ? [...this.memory.map((_, v) => v, stackBase, frameEnd)]
+              : [],
         },
         this: {
           base: THIS,