processJson method

@override Future<String> processJson(String jsonString)

Platform-specific: pass the unsigned transaction JSON, call the WASM module, and return the result JSON string.

WASM exports used: alloc, getUnsignedV2Transaction, resultPtr, resultLen, release.

Implementation

@override
Future<String> processJson(String jsonString) async {
  await _ensureInitialized();
  final instance = _instance!;
  final memory = _memory!;

  final bytes = utf8.encode(jsonString);

  // 1. Allocate WASM memory and write the input JSON
  final alloc = instance.getFunction('alloc')!;
  final ptr = alloc.inner(bytes.length) as int;
  memory.view.setRange(ptr, ptr + bytes.length, bytes);

  try {
    // 2. Call the main processing function
    final getUnsignedV2 = instance.getFunction('getUnsignedV2Transaction')!;
    final packedResult = getUnsignedV2.inner(ptr, bytes.length) as int;

    // 3. Extract the result pointer and length
    final resultPtrFn = instance.getFunction('resultPtr')!;
    final resultLenFn = instance.getFunction('resultLen')!;
    final resultPtr = resultPtrFn.inner(packedResult) as int;
    final resultLen = resultLenFn.inner(packedResult) as int;

    // 4. Read the result bytes, decode, and release the result memory
    final resultBytes = memory.view.sublist(resultPtr, resultPtr + resultLen);
    instance.getFunction('release')!.inner(resultPtr);

    return utf8.decode(resultBytes);
  } finally {
    // 5. Always release the input memory
    instance.getFunction('release')!.inner(ptr);
  }
}