feat: add support for launching with an initial state

changelog.md

@@ -11,6 +11,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - add `beforeLaunch` and `onLaunch` parameters to allow us to hook into the launching process
 - add `getBrowserFS` method for accessing the corresponding `BFSEmscriptenFS` object of the emulator
 - add a new method `sendCommand` for sending commands to RetroArch
+- add support for launching with an initial state
 
 ## [0.8.1](https://github.com/arianrhodsandlot/nostalgist/compare/v0.8.0...v0.8.1) - 2024-02-24
 

demo/demo.ts

@@ -4,7 +4,7 @@ let nostalgist: Nostalgist
 let state: Awaited<ReturnType<Nostalgist['saveState']>>
 
 async function nes() {
-  nostalgist = await Nostalgist.nes('flappybird.nes')
+  nostalgist = await Nostalgist.nes({ rom: 'flappybird.nes' })
 }
 
 async function megadrive() {
@@ -129,6 +129,7 @@ document.body.addEventListener('click', async function listener({ target }) {
     await handler()
     target.blur()
   }
+  Object.assign(window, { nostalgist })
 })
 
 // @ts-expect-error debug code

src/emulator.ts

@@ -48,13 +48,17 @@ export class Emulator {
     return fileName.slice(0, fileName.lastIndexOf('.'))
   }
 
-  private get stateFileName() {
+  private get stateFileDirectory() {
     const { core } = this.options
     const coreFullName = coreInfoMap[core.name].corename
     if (!coreFullName) {
       throw new Error(`invalid core name: ${core.name}`)
     }
-    return join(raUserdataDir, 'states', coreFullName, `${this.romBaseName}.state`)
+    return join(raUserdataDir, 'states', coreFullName)
+  }
+
+  private get stateFileName() {
+    return join(this.stateFileDirectory, `${this.romBaseName}.state`)
   }
 
   private get stateThumbnailFileName() {
@@ -278,7 +282,7 @@ export class Emulator {
   private async setupFileSystem() {
     const { Module } = this.getEmscripten()
     const { FS, PATH, ERRNO_CODES } = Module
-    const { rom, bios } = this.options
+    const { rom, bios, state } = this.options
 
     const browserFS = createEmscriptenFS({ FS, PATH, ERRNO_CODES })
     this.browserFS = browserFS
@@ -290,6 +294,9 @@ export class Emulator {
     if (bios.length > 0) {
       FS.mkdirTree(raSystemDir)
     }
+    if (state) {
+      FS.mkdirTree(this.stateFileDirectory)
+    }
 
     // a hack used for waiting for wasm's instantiation.
     // it's dirty but it works
@@ -302,10 +309,21 @@ export class Emulator {
       waitTime += 5
     }
 
-    await Promise.all([
+    const filePromises: Promise<void>[] = []
+    filePromises.push(
       ...rom.map((file) => this.writeBlobToDirectory({ ...file, directory: raContentDir })),
       ...bios.map((file) => this.writeBlobToDirectory({ ...file, directory: raSystemDir })),
-    ])
+    )
+    if (state) {
+      const statePromise = this.writeBlobToDirectory({
+        fileName: `${this.romBaseName}.state.auto`,
+        fileContent: state,
+        directory: this.stateFileDirectory,
+      })
+      filePromises.push(statePromise)
+    }
+    await Promise.all(filePromises)
+
     this.checkIsAborted()
   }
 
@@ -393,11 +411,13 @@ export class Emulator {
   private runMain() {
     this.checkIsAborted()
     const { Module } = this.getEmscripten()
-    const raArgs: string[] = []
-    const { rom } = this.options
-    if (rom.length > 0) {
-      const [{ fileName }] = rom
-      raArgs.push(join(raContentDir, fileName))
+    const { arguments: raArgs = [] } = Module
+    if (!Module.arguments) {
+      const { rom } = this.options
+      if (rom.length > 0) {
+        const [{ fileName }] = rom
+        raArgs.push(join(raContentDir, fileName))
+      }
     }
 
     Module.callMain(raArgs)

src/nostalgist.ts

@@ -458,6 +458,7 @@ export class Nostalgist {
     const {
       size = 'auto',
       respondToGlobalEvents = true,
+      state,
       waitForInteraction,
       signal,
       beforeLaunch,
@@ -485,6 +486,7 @@ export class Nostalgist {
       rom,
       bios,
       shader,
+      state,
       respondToGlobalEvents,
       retroarchConfig,
       retroarchCoreConfig,

src/options.ts

@@ -5,6 +5,7 @@ import { isAbsoluteUrl, path } from './utils'
 const defaultRetroarchConfig: RetroArchConfig = {
   menu_driver: 'rgui',
   notification_show_when_menu_is_alive: true,
+  savestate_auto_load: true,
   savestate_thumbnail_enable: true,
   stdin_cmd_enable: true,
   video_shader_enable: true,

src/types/emulator-options.ts

@@ -28,6 +28,7 @@ export interface EmulatorOptions {
   rom: { fileName: string; fileContent: Blob }[]
   bios: { fileName: string; fileContent: Blob }[]
   shader: { fileName: string; fileContent: Blob }[]
+  state?: Blob | undefined
 
   respondToGlobalEvents: boolean
 

src/types/nostalgist-options.ts

@@ -144,6 +144,8 @@ export interface NostalgistOptions {
    */
   bios?: NostalgistOptionsFiles
 
+  state?: Blob
+
   respondToGlobalEvents?: boolean
 
   /**

src/types/retroarch-config/skeleton.ts

@@ -13,8 +13,8 @@ export interface RetroArchSkeletonConfig {
    * The path is $SRAM_PATH.auto.
    * RetroArch will automatically load any savestate with this path on startup if savestate_auto_load is set.
    */
-  savestate_auto_save: string
-  savestate_auto_load: string
+  savestate_auto_save: boolean
+  savestate_auto_load: boolean
 
   /**
    * Path to a libretro implementation.

src/utils.ts

@@ -112,17 +112,22 @@ function isPrimitive(obj: unknown) {
   return primitevTypes.includes(type)
 }
 
+function isPlainObject(obj: any) {
+  const { constructor } = obj
+  return constructor === Object || !constructor
+}
+
 function mergeSourceToTarget(target: any, source: any) {
   for (const key in source) {
     if (Object.prototype.hasOwnProperty.call(source, key)) {
       const targetValue = target[key]
       const sourceValue = source[key]
-      if (isPrimitive(sourceValue)) {
+      if (isPrimitive(sourceValue) || !isPlainObject(sourceValue)) {
         target[key] = sourceValue
       } else if (Array.isArray(targetValue) && Array.isArray(sourceValue)) {
         target[key] = [...targetValue, ...sourceValue]
       } else {
-        target[key] = isPrimitive(targetValue) ? {} : target[key]
+        target[key] = isPrimitive(targetValue) || !isPlainObject(targetValue) ? {} : target[key]
         merge(target[key], sourceValue)
       }
     }