Convert Uint8List to Pointer<Uint8>

[Kevin Wu]

I have a dart:typed_data Uint8List from reading a gzip file and decompressing it with the archive package. I need to get a dart:ffi Pointer<Uint8> so that I can pass the pointer to a C native library using FFI. How do I get the address of the Uin8List's buffer?

Kevin

[Tim Sneath]

Try something like this:

extension Uint8ListBlobConversion on Uint8List {

  /// Allocates a pointer filled with the Uint8List data.

  Pointer<Uint8> allocatePointer() {

    final blob = calloc<Uint8>(length);

    final blobBytes = blob.asTypedList(length);

    blobBytes.setAll(0, this);

    return blob;

  }

}

[Kevin Wu]

Hi Tim,

Thank you for your suggestion. I think it will work, but may involve copying the buffer produced by the archive package into the blob. I will settle for that for now. I found some relevant links on this topic:

• https://github.com/dart-lang/ffi/issues/31
• https://github.com/dart-lang/ffi/issues/22
• https://stackoverflow.com/questions/60879616/dart-flutter-getting-data-array-from-c-c-using-ffi
• https://dev.to/kyorohiro/dart-and-c-how-to-ffi-and-wasm-4-buffer-pointer-1n8e

Kevin