Add a "speed governor" to control the execution speed for Basilisk II-based machines

Uses the instruction count reported by mihaip/macemu@683bc64
to implement support for Mini vMac's speed setting in Basilisk II too.
We set a target instructions per second (IPS) count, and then add
sleep time to try to hit it.

Fixes #372

Author: mihaip

macemu

@@ -490,6 +490,7 @@ export default function Mac({
         cdroms,
         machine,
         ethernetProvider,
+        screenSizeProp,
         initialScreenWidth,
         initialScreenHeight,
         customDate,

src/Mac.tsx

@@ -9,6 +9,10 @@
     margin-right: 4px;
 }
 
+.MacSettings-Row label {
+    display: inline;
+}
+
 .MacSettings-Row .Dialog-Description {
     margin-left: 104px;
 }

src/MacSettings.css

@@ -69,48 +69,54 @@ export function MacSettings({
 
     return (
         <Dialog title="Settings" onDone={onDone}>
-            <label>
-                <Checkbox
-                    checked={emulatorSettings.swapControlAndCommand}
-                    onChange={() =>
-                        setEmulatorSettings({
-                            ...emulatorSettings,
-                            swapControlAndCommand:
-                                !emulatorSettings.swapControlAndCommand,
-                        })
-                    }
-                />
-                Swap Control and Command Keys
+            <div className="MacSettings-Row">
+                <div className="MacSettings-Row-Label">Input:</div>
+                <label>
+                    <Checkbox
+                        checked={emulatorSettings.swapControlAndCommand}
+                        onChange={() =>
+                            setEmulatorSettings({
+                                ...emulatorSettings,
+                                swapControlAndCommand:
+                                    !emulatorSettings.swapControlAndCommand,
+                            })
+                        }
+                    />
+                    Swap Control and Command Keys
+                </label>
                 <div className="Dialog-Description">
                     Makes it easier to use shortcuts like Command-W, Command-Q
                     or Command-Shift-3 (which are otherwise handled by the host
                     browser or OS).
                 </div>
-            </label>
+            </div>
             {emulatorSupportsMouseDeltas(emulatorType) &&
                 !emulatorSettings.trackpadMode && (
-                    <label>
-                        <Checkbox
-                            checked={emulatorSettings.useMouseDeltas}
-                            onChange={() =>
-                                setEmulatorSettings({
-                                    ...emulatorSettings,
-                                    useMouseDeltas:
-                                        !emulatorSettings.useMouseDeltas,
-                                })
-                            }
-                        />
-                        Use relative mouse movements
+                    <div className="MacSettings-Row">
+                        <div className="MacSettings-Row-Label" />
+                        <label>
+                            <Checkbox
+                                checked={emulatorSettings.useMouseDeltas}
+                                onChange={() =>
+                                    setEmulatorSettings({
+                                        ...emulatorSettings,
+                                        useMouseDeltas:
+                                            !emulatorSettings.useMouseDeltas,
+                                    })
+                                }
+                            />
+                            Use relative mouse movements
+                        </label>
                         <div className="Dialog-Description">
                             Send relative mouse movements to the emulator
                             instead of absolute positions. This can help with
                             compatibility of games such as Apeiron.
                         </div>
-                    </label>
+                    </div>
                 )}
             {emulatorSupportsSpeedSetting(emulatorType) && (
-                <label>
-                    Speed:
+                <div className="MacSettings-Row">
+                    <div className="MacSettings-Row-Label">Speed:</div>
                     <Select
                         value={emulatorSettings.speed}
                         onChange={event =>
@@ -131,10 +137,9 @@ export function MacSettings({
                         )}
                     </Select>
                     <div className="Dialog-Description">
-                        Very old software may be timing dependent and thus only
-                        work at 1x speeds.
+                        Very old software may be timing dependent.
                     </div>
-                </label>
+                </div>
             )}
             <div className="MacSettings-Row">
                 <div className="MacSettings-Row-Label">Scaling:</div>

src/MacSettings.tsx

@@ -41,7 +41,7 @@ export function emulatorUsesPlaceholderDisks(type: EmulatorType): boolean {
 }
 
 export function emulatorSupportsSpeedSetting(type: EmulatorType): boolean {
-    return type === "Mini vMac";
+    return type === "Mini vMac" || type === "BasiliskII";
 }
 
 // True if the emulator can optionally use mouse deltas instead of absolute

src/emulator/BasiliskII.js

@@ -165,6 +165,7 @@ export type EmulatorWorkerConfig = EmulatorDef & {
     ethernet: EmulatorWorkerEthernetConfig;
     clipboard: EmulatorWorkerClipboardConfig;
     dateOffset: number;
+    speedGovernorTargetIPS?: number;
 };
 
 export type EmulatorWorkerVideoConfig =

src/emulator/BasiliskII.wasm

@@ -370,7 +370,8 @@ export class Emulator {
 
         let args: string[] = [];
         let configDebugStr;
-        const {emulatorType, emulatorSubtype} = this.#config.machine;
+        const {emulatorType, emulatorSubtype, speedGovernorTargetIPS} =
+            this.#config.machine;
         switch (emulatorType) {
             case "DingusPPC":
                 args = configToDingusPPCArgs(this.#config, {
@@ -459,6 +460,7 @@ export class Emulator {
             ethernet: this.#ethernet.workerConfig(),
             clipboard: this.#clipboard.workerConfig(),
             dateOffset,
+            speedGovernorTargetIPS,
         };
 
         const serviceWorkerAvailable = await this.#serviceWorkerReady;

src/emulator/emulator-common-emulators.ts

@@ -10,20 +10,23 @@ import {type EmulatorFallbackEndpoint} from "./emulator-worker";
 
 export interface EmulatorWorkerInput {
     idleWait(timeout: number): boolean;
+    sleep(timeout: number): void;
     acquireInputLock(): number;
     releaseInputLock(): void;
     getInputValue(addr: number): number;
 }
 
 export class SharedMemoryEmulatorWorkerInput implements EmulatorWorkerInput {
     #inputBufferView: Int32Array;
+    #sleepInputBufferView: Int32Array;
 
     constructor(config: EmulatorWorkerSharedMemoryInputConfig) {
         this.#inputBufferView = new Int32Array(
             config.inputBuffer,
             0,
             config.inputBufferSize
         );
+        this.#sleepInputBufferView = new Int32Array(new SharedArrayBuffer(4));
     }
 
     idleWait(timeout: number): boolean {
@@ -37,6 +40,12 @@ export class SharedMemoryEmulatorWorkerInput implements EmulatorWorkerInput {
         return hadInput;
     }
 
+    sleep(timeout: number): void {
+        // sleepInputBufferView will never change, just use it to wait
+        // efficiently.
+        Atomics.wait(this.#sleepInputBufferView, 0, 0, timeout);
+    }
+
     acquireInputLock(): number {
         const hasLock = tryToAcquireCyclicalLock(
             this.#inputBufferView,
@@ -117,6 +126,14 @@ export class FallbackEmulatorWorkerInput implements EmulatorWorkerInput {
         return false;
     }
 
+    sleep(timeout: number): void {
+        const endTime = performance.now() + timeout;
+        while (performance.now() < endTime) {
+            // Not worth hitting the fallback endpoint, the timeouts are too
+            // short.
+        }
+    }
+
     acquireInputLock(): number {
         this.#inputQueue = this.#inputQueue.concat(
             this.#fallbackEndpoint.consumeInputEvents()