mgpuReadAsyncInt8 function

Future<void> mgpuReadAsyncInt8(MGPUBuffer buffer, Int8List outputData, { int readElements = 0, int elementOffset = 0, })

Asynchronous read functions for multiple types. Each function allocates native memory, calls ccall with async:true, then copies the data from the WebAssembly heap into the given Dart TypedData.

Implementation

Future<void> mgpuReadAsyncInt8(
  MGPUBuffer buffer,
  Int8List outputData, {
  int readElements = 0,
  int elementOffset = 0,
}) async {
  final int bytesPerElem = Int8List.bytesPerElement;
  // Calculate element count based on outputData size if readElements is 0
  final int elementsToRead = (readElements > 0)
      ? readElements
      : (outputData.length - elementOffset);
  final int sizeToAllocate =
      elementsToRead * bytesPerElem; // Allocate based on elements

  if (elementsToRead <= 0 ||
      elementOffset < 0 ||
      elementOffset >= outputData.length)
    return; // Nothing to read or invalid offset

  final JSNumber ptr = _malloc(sizeToAllocate.toJS);
  final int startIndex = ptr.toDartInt; // Byte index for heap copy

  try {
    // Add bounds check
    if (startIndex < 0 || startIndex + sizeToAllocate > _heapU8.length) {
      throw StateError(
        'Int8 buffer read would exceed heap bounds: '
        'trying to read $elementsToRead elements at index $startIndex '
        'but heap size is ${_heapU8.length}',
      );
    }
    await ccall(
      "mgpuReadSyncInt8".toJS, // Use sync C++ function
      "void".toJS, // C++ function returns void
      ["number", "number", "number", "number"].toJSDeep,
      [buffer, ptr, elementsToRead.toJS, elementOffset.toJS].toJSDeep,
      {"async": true}.toJSDeep,
    ).toDart;

    // Copy the data from WASM heap
    // startIndex is the byte offset, elementsToRead is the count
    final output = _heapI8.sublist(startIndex, startIndex + elementsToRead);
    outputData.setAll(elementOffset, output);
  } finally {
    _free(ptr);
  }
}