zero copy ffi w/ unsafe-pointers (built for this purpose)

Author: justjake

bun.lock

@@ -23,6 +23,7 @@
     "test:dist": "bun scripts/dist-test.ts --build packages/*/dist-test/*"
   },
   "devDependencies": {
+    "commander": "^13.1.0",
     "oxfmt": "0.41.0",
     "oxlint": "1.56.0",
     "vitest": "4.1.3"

package.json

@@ -0,0 +1,2 @@
+[test]
+root = "src"

packages/core/bunfig.toml

@@ -33,7 +33,6 @@
     "@types/bun": "latest",
     "@types/node": "^24.0.0",
     "@types/three": "0.177.0",
-    "commander": "^13.1.0",
     "typescript": "^5",
     "web-tree-sitter": "0.25.10"
   },
@@ -51,16 +50,17 @@
   },
   "optionalDependencies": {
     "@dimforge/rapier2d-simd-compat": "^0.17.3",
-    "koffi": "2.15.6",
-    "bun-webgpu": "0.1.5",
-    "planck": "^1.4.2",
-    "three": "0.177.0",
-    "@opentui/core-darwin-x64": "0.1.97",
     "@opentui/core-darwin-arm64": "0.1.97",
-    "@opentui/core-linux-x64": "0.1.97",
+    "@opentui/core-darwin-x64": "0.1.97",
     "@opentui/core-linux-arm64": "0.1.97",
+    "@opentui/core-linux-x64": "0.1.97",
+    "@opentui/core-win32-arm64": "0.1.97",
     "@opentui/core-win32-x64": "0.1.97",
-    "@opentui/core-win32-arm64": "0.1.97"
+    "bun-webgpu": "0.1.5",
+    "koffi": "2.15.6",
+    "planck": "^1.4.2",
+    "three": "0.177.0",
+    "unsafe-pointer": "0.2.0"
   },
   "exports": {
     ".": {

packages/core/package.json

@@ -0,0 +1,35 @@
+import { describe, it, expect } from "bun:test"
+import * as ffi from "./ffi.js"
+
+describe("ffi", () => {
+  it("can round-trip a Uint8Array", () => {
+    const array = new TextEncoder().encode("Hello, world!")
+    const pointer = ffi.ptr(array)
+    const newArrayBuffer = ffi.toArrayBuffer(pointer, 0, array.byteLength)
+    const newArray = new Uint8Array(newArrayBuffer)
+
+    expect(newArray).toEqual(array)
+    expect(new TextDecoder().decode(newArrayBuffer)).toBe("Hello, world!")
+  })
+
+  it("aliases Pointer memory", () => {
+    const array = new TextEncoder().encode("Hello, world!")
+    const pointer = ffi.ptr(array)
+    const newArrayBuffer = ffi.toArrayBuffer(pointer, 0, array.byteLength)
+    const newArray = new Uint8Array(newArrayBuffer)
+
+    expect(array[0]).not.toBe(0)
+    newArray[0] = 0
+    expect(array[0]).toBe(0)
+  })
+
+  it("returns stable address", () => {
+    const array = new TextEncoder().encode("Hello, world!")
+    const pointer = ffi.ptr(array)
+    const newArrayBuffer = ffi.toArrayBuffer(pointer, 0, array.byteLength)
+    const newArray = new Uint8Array(newArrayBuffer)
+
+    expect(pointer).toBe(ffi.ptr(newArray))
+    expect(pointer).toBe(ffi.ptr(newArrayBuffer))
+  })
+})

packages/core/src/compat/ffi.test.ts

@@ -151,11 +151,7 @@ export interface JSCallbackConstructor {
 
 export type DlopenFunction = <Fns extends Record<string, FFIFunction>>(name: string | URL, symbols: Fns) => Library<Fns>
 export type PtrFunction = (value: ArrayBufferLike | ArrayBufferView) => Pointer
-export type ToArrayBufferFunction = (
-  pointer: Pointer | bigint | object | null,
-  offset?: number,
-  length?: number,
-) => ArrayBuffer
+export type ToArrayBufferFunction = (pointer: Pointer, offset: number | undefined, length: number) => ArrayBuffer
 
 type FfiModule = {
   JSCallback: JSCallbackConstructor