index.ts

export = {
  /** Check support WebAssembly version */
  support(version = 1) {
    return exists && check(Uint32Array.of(0x6D736100, version))
  },

  /** Check support streaming compilation and instantiation */
  get supportStreaming() { return exists && has(WA.instantiateStreaming) },

  feature: {
    /** Check support JavaScript BigInt to WebAssembly i64 integration (--experimental-wasm-bigint) */
    get bigInt() { return check(bigIntWasm, true) },
    /** Check support bulk memory operations (--experimental-wasm-bulk-memory) */
    get bulk() { return check(bulkWasm) },
    /** Check support exception handling (--experimental-wasm-eh) */
    get exceptions() { return check(exceptionsWasm) },
    /** Check support 64-bit memory (--experimental-wasm-memory64) */
    get memory64() { return check(memory64Wasm) },
    /** Check support import & export of mutable global (--experimental-wasm-mut-global) */
    get mutableGlobal() { return check(mutableGlobalWasm) },
    /** Check support multi values (--experimental-wasm-mv) */
    get multiValue() { return check(multiValueWasm) },
    /** Check support non-trapping float-to-int conversions (--experimental-wasm-sat-f2i-conversions) */
    get saturateConversions() { return check(saturateConversionsWasm) },
    /** Check support zero and sign extensions (--experimental-wasm-se) */
    get signExtensions() { return check(signExtensionsWasm) },
    /** Check support tail call optiminations (--experimental-wasm-return-call) */
    get tailCall() { return check(tailCallWasm) },
    /** Check support threads and atomics (--experimental-wasm-threads) */
    get threads() { return check(threadsWasm) },
    /** Check support SIMD (--experimental-wasm-simd) */
    get simd() { return check(simdWasm) },
    /** Check support basic reference types "externref" (--experimental-wasm-reftypes) */
    get references() { return check(referencesWasm) },
    /** Check support Type Reflection (--experimental-wasm-type-reflection) */
    get typeReflection() { return exists && has((<any>WA.Memory).type) },
    /** Check support typed function references and closures (pre-proposal) */
    get funcReferences() { return exists && has((<any>WA).Function) },
    /* TODO
     * - GC
     * - Web IDL Bindings (Host binding) ?
     */
  }
}

function check(
  wasm: ArrayBufferView,
  exec?: boolean
) {
  if (!exists) return false
  const buffer = wasm.buffer
  let ok = cache.get(buffer)
  if (ok == null) {
    if ((ok = WA.validate(buffer)) && exec) {
      try {
        (new WA.Instance(
          new WA.Module(buffer)
        ).exports['0'] as Function)()
      } catch { ok = false }
    }
    cache.set(buffer, ok!)
  }
  return ok!
}

const WA = (<any>this).WebAssembly || globalThis.WebAssembly
const exists = typeof WA === 'object'
const has = (entity: unknown) => typeof entity !== 'undefined'

const u8   = (...bytes: number[]) => Uint8Array.of(0, 97, 115, 109, 1, 0, 0, 0, ...bytes)
// const u16  = (...bytes: number[]) => Uint16Array.of(24832, 28019, 1, 0, ...bytes)
const u32  = (...bytes: number[]) => Uint32Array.of(0x6D736100, 1, ...bytes)
const u32a = (...bytes: number[]) => u32(1610679297, 33751040, ...bytes, 40239360, 259)

const u8a  = (...bytes: number[]) => u8(1, 4, 1, 96, 0, 0, 3, 2, 1, 0, ...bytes, 11, 0, 10, 4, 110, 97, 109, 101, 2, 3, 1, 0, 0)
const u16a = (...bytes: number[]) => Uint16Array.of(24832, 28019, 1, 0, 1025, 24577, 0, 515, 1, ...bytes)
const u16b = (...bytes: number[]) => u16a(...bytes, 2842, 4096, 28164, 28001, 357, 260, 256, 560, 259, 0)

const cache = new WeakMap<ArrayBufferLike, boolean>()

const bigIntWasm = u32(
  1610679553, 58589440, 117440770, 805372165, 101318656, 1107297281, 268438272,
  1835101700, 17039717, 36700416,  259
)

const memory64Wasm = u8(
  5, 3, 1, 4, 1, 0, 8, 4, 110, 97, 109, 101, 2, 1, 0
)

const bulkWasm = u16a(
  773, 1, 2561, 269, 11, 65, 65, 65, 3068, 2816, 2560, 28164, 28001, 613, 259, 0
)

const exceptionsWasm = u32(
  1610679297, 33751040, 134873089, 100664833, 185276736
)

const mutableGlobalWasm = u8(
  2, 8, 1, 1, 97, 1, 98, 3, 127, 1, 6, 6, 1, 127, 1, 65, 0, 11, 7, 5, 1, 1, 97,
  3, 1, 0, 8, 4, 110, 97, 109, 101, 2, 1, 0
)

const multiValueWasm = Uint16Array.of(
  24832, 28019, 1, 0, 1537, 24577, 512, 32639, 515, 1, 2058,
  1537, 16640, 16640, 2816, 2560, 28164, 28001, 613, 259, 0
)

const saturateConversionsWasm = u16b(
  3082, 2561, 17152, 0, 0, 252
)

const signExtensionsWasm = u16b(
  2058, 1537, 16640, 49152
)

const tailCallWasm = u32a(
  101318657, 301990913, 268438272, 1835101700, 17039717
)

const threadsWasm = u8a(
  5, 4, 1, 3, 1, 1, 10, 7, 1, 5, 0, 254, 3, 0
)

const simdWasm = u32a(
  84344833, 6357249, 17369600, 4259847, 186257917, 1845758464
)

const referencesWasm = u8a(
  10, 7, 1, 5, 0, 208, 112, 26
)