decodeCOBSStream function

Stream<ByteData> decodeCOBSStream(Stream<ByteData> source)

Decodes a stream of COBS-encoded bytes into packets of decoded bytes.

The input bytes are provided in chunks through the source stream.

Implementation

Stream<ByteData> decodeCOBSStream(Stream<ByteData> source) async* {
  // Stores any partial packets from the previous chunk.
  var partial = ByteData(0);

  // Wait until a chunk is available, then process it.
  await for (var chunk in source) {
    // Get index of 0x00 byte if found
    var offset = 0;
    for (var i = 0; i < chunk.lengthInBytes; i++) {
      if (chunk.getUint8(i) == 0x00) {
        // Packet delimiter found, now decode it
        int encodedLength = partial.lengthInBytes + i - offset;
        var encoded = ByteData(encodedLength);
        var index = 0;
        for (var ip = 0; ip < partial.lengthInBytes; ip++) {
          encoded.setUint8(index, partial.getUint8(ip));
          index++;
        }
        for (var ie = offset; ie < i; ie++) {
          encoded.setUint8(index, chunk.getUint8(ie));
          index++;
        }

        partial = ByteData(0);
        offset = i + 1;

        ByteData decoded = ByteData(decodeDstBufMaxLen(encodedLength));
        DecodeResult result = decodeCOBS(decoded, encoded);
        if (result.status == DecodeStatus.OK) {
          yield ByteData.view(decoded.buffer, 0, result.outLen);
        }
      }
    }
    partial = chunk.buffer.asByteData(offset, chunk.lengthInBytes - offset);
  }
}