From 1ab5a9d0d70bc34c5668f320ee870dd652aa9edd Mon Sep 17 00:00:00 2001
From: jberg <jberg@users.noreply.github.com>
Date: Sat, 20 Jul 2019 16:39:19 -0700
Subject: [PATCH] Add runtime version and remove version check hacks (#818)

* add runtime version and remove version check hacks

* move jump logic into a shared function
---
 .../src/maki-interpreter/virtualMachine.js    | 36 +++++++++----------
 experiments/modern/src/runtime/System.js      |  3 ++
 2 files changed, 21 insertions(+), 18 deletions(-)

diff --git a/experiments/modern/src/maki-interpreter/virtualMachine.js b/experiments/modern/src/maki-interpreter/virtualMachine.js
index 86df8082..af48ca20 100644
--- a/experiments/modern/src/maki-interpreter/virtualMachine.js
+++ b/experiments/modern/src/maki-interpreter/virtualMachine.js
@@ -32,9 +32,11 @@ async function interpret(start, program, stack = [], { logger = null }) {
     stack.push(operator(bValue, aValue));
   }
 
-  // Run all the commands that are safe to run. Increment this number to find
-  // the next bug.
-  const maxOffset = Math.max(...Object.keys(offsetToCommand));
+  function jumpToOffset(offset) {
+    const nextCommandIndex = offsetToCommand[offset];
+    return nextCommandIndex - 1;
+  }
+
   let i = start;
   while (i < commands.length) {
     const command = commands[i];
@@ -103,16 +105,22 @@ async function interpret(start, program, stack = [], { logger = null }) {
         if (value) {
           break;
         }
-        const offset = command.arg;
-        const nextCommandIndex = offsetToCommand[offset];
-        i = nextCommandIndex - 1;
+        i = jumpToOffset(command.arg);
+        break;
+      }
+      // jumpIfNot
+      case 17: {
+        const value = stack.pop();
+        // This seems backwards. Same as above
+        if (!value) {
+          break;
+        }
+        i = jumpToOffset(command.arg);
         break;
       }
       // jump
       case 18: {
-        const offset = command.arg;
-        const nextCommandIndex = offsetToCommand[offset];
-        i = nextCommandIndex - 1;
+        i = jumpToOffset(command.arg);
         break;
       }
       // call
@@ -140,15 +148,7 @@ async function interpret(start, program, stack = [], { logger = null }) {
       }
       // callGlobal
       case 25: {
-        let offset = command.arg;
-        // This is where the version checked wa5 scripts start with this offset
-        if (offset === 0) {
-          // skip ahead to where the real program begins
-          // TODO: Why is this magic?
-          i = i + 3;
-          break;
-        }
-        // handle offsets that are over maxOffset that seem to be the wrong sign
+        const offset = command.arg;
         const nextCommandIndex = offsetToCommand[offset];
         // Remove this await when we can run the VM synchronously.
         // See GitHub issue #814
diff --git a/experiments/modern/src/runtime/System.js b/experiments/modern/src/runtime/System.js
index da63e870..5d551bfe 100644
--- a/experiments/modern/src/runtime/System.js
+++ b/experiments/modern/src/runtime/System.js
@@ -21,6 +21,9 @@ class System extends MakiObject {
   getScriptGroup() {
     return new Group();
   }
+  getRuntimeVersion() {
+    return "5.666";
+  }
   getToken(str, separator, tokennum) {
     return "Some Token String";
   }