Changed the way VM input is handled.

Now the VM informs the runner when it requires input via ExecutionResult. Input is provided to the VM by calling methods directly on it.
Also implemented opcode list.

src/quest_editor/QuestRunner.ts

@@ -26,6 +26,10 @@ export class QuestRunner {
         this.vm.load_object_code(quest.object_code);
         this.vm.start_thread(0);
 
+        this.schedule_frame();
+    }
+
+    private schedule_frame(): void {
         this.animation_frame = requestAnimationFrame(this.execution_loop);
     }
 
@@ -38,17 +42,26 @@ export class QuestRunner {
             result = this.vm.execute();
         } while (result == ExecutionResult.Ok);
 
-        if (result === ExecutionResult.WaitingVsync) {
+        switch (result) {
-            this.animation_frame = requestAnimationFrame(this.execution_loop);
+            case ExecutionResult.WaitingVsync:
+                this.schedule_frame();
+                break;
+            case ExecutionResult.WaitingInput:
+                // TODO: implement input from gui
+                this.schedule_frame();
+                break;
+            case ExecutionResult.WaitingSelection:
+                // TODO: implement input from gui
+                this.vm.list_select(0);
+                this.schedule_frame();
+                break;
+            case ExecutionResult.Halted:
+                break;
         }
     };
 
     private create_vm_io = (): VirtualMachineIO => {
         return {
-            async advance_msg(): Promise<any> {
-                throw new Error("Not implemented.");
-            },
-
             window_msg: (msg: string): void => {
                 logger.info(`window_msg "${msg}"`);
             },
@@ -65,6 +78,10 @@ export class QuestRunner {
 
             mesend: (): void => {},
 
+            list: (list_items: string[]): void => {
+                logger.info(`list "[${list_items}]"`);
+            },
+
             warning: (msg: string, srcloc?: AsmToken): void => {
                 logger.warning(msg, srcloc && srcloc_to_string(srcloc));
             },

src/quest_editor/scripting/vm/VMIOStub.ts

@@ -6,16 +6,12 @@ import { VirtualMachineIO } from "./io";
  * All methods of VirtualMachineIO implemented as stubs.
  */
 export class VMIOStub implements VirtualMachineIO {
-    @stub
-    advance_msg(): Promise<any> {
-        return Promise.resolve();
-    }
-
     @stub window_msg(msg: string): void {}
     @stub message(msg: string): void {}
     @stub add_msg(msg: string): void {}
     @stub winend(): void {}
     @stub mesend(): void {}
+    @stub list(list_items: string[]): void {}
     @stub warning(msg: string, srcloc?: AsmToken): void {}
     @stub error(err: Error, srcloc?: AsmToken): void {}
 }

src/quest_editor/scripting/vm/index.ts

@@ -82,6 +82,7 @@ import {
     OP_GET_RANDOM,
     OP_GETTIME,
     OP_SET_EPISODE,
+    OP_LIST,
 } from "../opcodes";
 import { VirtualMachineMemoryBuffer, VirtualMachineMemory } from "./memory";
 import {
@@ -110,11 +111,21 @@ const STRING_ARG_STORE_ADDRESS = 0x00a92700;
 const STRING_ARG_STORE_SIZE = 1024; // TODO: verify this value
 const FLOAT_EPSILON = 1.19e-7;
 const ENTRY_SEGMENT = 0;
+const LIST_ITEM_DELIMITER = "\n";
 
 export enum ExecutionResult {
     Ok,
     WaitingVsync,
     Halted,
+    /**
+     * Waiting for any keypress. No method call required.
+     */
+    WaitingInput,
+    /**
+     * Waiting for a value to be selected in a list.
+     * Call `list_select` to set selection.
+     */
+    WaitingSelection,
 }
 
 function encode_episode_number(ep: Episode): number {
@@ -145,6 +156,8 @@ export class VirtualMachine {
     private thread_idx = 0;
     private window_msg_open = false;
     private set_episode_called = false;
+    private list_open = false;
+    private selection_reg = 0;
 
     constructor(private io: VirtualMachineIO = new VMIOStub()) {
         srand(GetTickCount());
@@ -252,6 +265,8 @@ export class VirtualMachine {
         if (this.thread.length === 0) return ExecutionResult.Halted;
         if (this.thread_idx >= this.thread.length) return ExecutionResult.WaitingVsync;
 
+        let result = ExecutionResult.Ok;
+
         const arg_vals = inst.args.map(arg => arg.value);
         // eslint-disable-next-line
         const [arg0, arg1, arg2, arg3, arg4, arg5, arg6, arg7] = arg_vals;
@@ -267,6 +282,12 @@ export class VirtualMachine {
             arg1,
         ];
 
+        // previous instruction must've been `list`.
+        // list may not exist after the instruction
+        if (this.list_open) {
+            this.list_open = false;
+        }
+
         switch (inst.opcode.code) {
             case OP_NOP.code:
                 break;
@@ -565,11 +586,23 @@ export class VirtualMachine {
             case OP_STACK_POPM.code:
                 this.pop_variable_stack(exec, arg0, arg1);
                 break;
+            case OP_LIST.code:
+                if (!this.window_msg_open) {
+                    const args = exec.fetch_args(inst);
+                    const list_items = this.deref_string(args[1]).split(LIST_ITEM_DELIMITER);
+
+                    result = ExecutionResult.WaitingSelection;
+                    this.list_open = true;
+                    this.selection_reg = args[0];
+                    this.io.list(list_items);
+                }
+                break;
             case OP_WINDOW_MSG.code:
                 if (!this.window_msg_open) {
                     const args = exec.fetch_args(inst);
                     const str = this.deref_string(args[0]);
 
+                    result = ExecutionResult.WaitingInput;
                     this.window_msg_open = true;
                     this.io.window_msg(str);
                 }
@@ -579,6 +612,7 @@ export class VirtualMachine {
                     const args = exec.fetch_args(inst);
                     const str = this.deref_string(args[0]);
 
+                    result = ExecutionResult.WaitingInput;
                     this.io.add_msg(str);
                 }
                 break;
@@ -662,7 +696,7 @@ export class VirtualMachine {
 
         if (this.thread.length === 0) return ExecutionResult.Halted;
         if (this.thread_idx >= this.thread.length) return ExecutionResult.WaitingVsync;
-        return ExecutionResult.Ok;
+        return result;
     }
 
     /**
@@ -966,6 +1000,16 @@ export class VirtualMachine {
             srcloc,
         );
     }
+
+    /**
+     * When the list opcode is used, call this method to select a value in the list.
+     */
+    public list_select(idx: number): void {
+        if (!this.list_open) {
+            throw new Error("list_select may not be called if there is no list open");
+        }
+        this.set_register_unsigned(this.selection_reg, idx);
+    }
 }
 
 class ExecutionLocation {

src/quest_editor/scripting/vm/io.ts

@@ -3,12 +3,7 @@ import { AsmToken } from "../instructions";
 /**
  * The virtual machine calls these methods when it requires input.
  */
-export interface VirtualMachineInput {
+export interface VirtualMachineInput {}
-    /**
-     * End the current message and move to the next message.
-     */
-    advance_msg(): Promise<any>;
-}
 
 /**
  * The virtual machine calls these methods when it outputs something.
@@ -19,6 +14,7 @@ export interface VirtualMachineOutput {
     add_msg(msg: string): void;
     winend(): void;
     mesend(): void;
+    list(list_items: string[]): void;
 }
 
 /**