packages/wasm-bridge/src/bridge.ts
// Copyright 2019-2024 @polkadot/wasm-bridge authors & contributors
// SPDX-License-Identifier: Apache-2.0
// A number of functions are "unsafe" and purposefully so - it is
// assumed that where the bridge is used, it is correctly wrapped
// in a safeguard (see withWasm in the wasm-crypto package) which
// then ensures that the internal wasm instance here is available
/* eslint-disable @typescript-eslint/no-non-null-assertion */
import type { BridgeBase, InitFn, InitPromise, WasmBaseInstance, WasmImports } from './types.js';
import { stringToU8a, u8aToString } from '@polkadot/util';
import { Wbg } from './wbg.js';
/**
* @name Bridge
* @description
* Creates a bridge between the JS and WASM environments.
*
* For any bridge it is passed an function which is then called internally at the
* time of initialization. This affectively implements the layer between WASM and
* the native environment, providing all the plumbing needed for the Wbg classes.
*/
export class Bridge<C extends WasmBaseInstance> implements BridgeBase<C> {
readonly #createWasm: InitFn<C>;
readonly #heap: unknown[];
readonly #wbg: WasmImports;
#cachegetInt32: Int32Array | null;
#cachegetUint8: Uint8Array | null;
#heapNext: number;
#wasm: C | null;
#wasmError: string | null;
#wasmPromise: InitPromise<C> | null;
#type: 'asm' | 'wasm' | 'none';
constructor (createWasm: InitFn<C>) {
this.#createWasm = createWasm;
this.#cachegetInt32 = null;
this.#cachegetUint8 = null;
this.#heap = new Array(32)
.fill(undefined)
.concat(undefined, null, true, false);
this.#heapNext = this.#heap.length;
this.#type = 'none';
this.#wasm = null;
this.#wasmError = null;
this.#wasmPromise = null;
this.#wbg = { ...new Wbg(this) };
}
/** @description Returns the init error */
get error (): string | null {
return this.#wasmError;
}
/** @description Returns the init type */
get type (): 'asm' | 'wasm' | 'none' {
return this.#type;
}
/** @description Returns the created wasm interface */
get wasm (): C | null {
return this.#wasm;
}
/** @description Performs the wasm initialization */
async init (createWasm?: InitFn<C>): Promise<C | null> {
if (!this.#wasmPromise || createWasm) {
this.#wasmPromise = (createWasm || this.#createWasm)(this.#wbg);
}
const { error, type, wasm } = await this.#wasmPromise;
this.#type = type;
this.#wasm = wasm;
this.#wasmError = error;
return this.#wasm;
}
/**
* @internal
* @description Gets an object from the heap
*/
getObject (idx: number): unknown {
return this.#heap[idx];
}
/**
* @internal
* @description Removes an object from the heap
*/
dropObject (idx: number) {
if (idx < 36) {
return;
}
this.#heap[idx] = this.#heapNext;
this.#heapNext = idx;
}
/**
* @internal
* @description Retrieves and removes an object to the heap
*/
takeObject (idx: number): unknown {
const ret = this.getObject(idx);
this.dropObject(idx);
return ret;
}
/**
* @internal
* @description Adds an object to the heap
*/
addObject (obj: unknown): number {
if (this.#heapNext === this.#heap.length) {
this.#heap.push(this.#heap.length + 1);
}
const idx = this.#heapNext;
this.#heapNext = this.#heap[idx] as number;
this.#heap[idx] = obj;
return idx;
}
/**
* @internal
* @description Retrieve an Int32 in the WASM interface
*/
getInt32 (): Int32Array {
if (this.#cachegetInt32 === null || this.#cachegetInt32.buffer !== this.#wasm!.memory.buffer) {
this.#cachegetInt32 = new Int32Array(this.#wasm!.memory.buffer);
}
return this.#cachegetInt32;
}
/**
* @internal
* @description Retrieve an Uint8Array in the WASM interface
*/
getUint8 (): Uint8Array {
if (this.#cachegetUint8 === null || this.#cachegetUint8.buffer !== this.#wasm!.memory.buffer) {
this.#cachegetUint8 = new Uint8Array(this.#wasm!.memory.buffer);
}
return this.#cachegetUint8;
}
/**
* @internal
* @description Retrieves an Uint8Array in the WASM interface
*/
getU8a (ptr: number, len: number): Uint8Array {
return this.getUint8().subarray(ptr / 1, ptr / 1 + len);
}
/**
* @internal
* @description Retrieves a string in the WASM interface
*/
getString (ptr: number, len: number): string {
return u8aToString(this.getU8a(ptr, len));
}
/**
* @internal
* @description Allocates an Uint8Array in the WASM interface
*/
allocU8a (arg: Uint8Array): [number, number] {
const ptr = this.#wasm!.__wbindgen_malloc(arg.length * 1);
this.getUint8().set(arg, ptr / 1);
return [ptr, arg.length];
}
/**
* @internal
* @description Allocates a string in the WASM interface
*/
allocString (arg: string): [number, number] {
return this.allocU8a(stringToU8a(arg));
}
/**
* @internal
* @description Retrieves an Uint8Array from the WASM interface
*/
resultU8a (): Uint8Array {
const r0 = this.getInt32()[8 / 4 + 0];
const r1 = this.getInt32()[8 / 4 + 1];
const ret = this.getU8a(r0, r1).slice();
this.#wasm!.__wbindgen_free(r0, r1 * 1);
return ret;
}
/**
* @internal
* @description Retrieve a string from the WASM interface
*/
resultString (): string {
return u8aToString(this.resultU8a());
}
}