readFromBufferAsUnsigned function

int readFromBufferAsUnsigned(Pointer<Uint8> buffer, int offset, int byteCnt)

Read a specified piece of the buffer and convert it to an integer number (unsigned).

If offset is aligned, tat is if (offset mod byteCnt) = 0, the function chooses more efficient implementation. On unaligned data, byte-by-byte copying takes place. The only valid values for byteCnt are 1, 2, 4 and 8 (any other will cause a MemException).

Implementation

int readFromBufferAsUnsigned(Pointer<Uint8> buffer, int offset, int byteCnt) {
  if (offset % byteCnt == 0) {
    // the offset is aligned
    switch (byteCnt) {
      case 1:
        return buffer[offset];
      case 2:
        return Pointer<Uint16>.fromAddress(buffer.address + offset)
            .asTypedList(1)[0];
      case 4:
        return Pointer<Uint32>.fromAddress(buffer.address + offset)
            .asTypedList(1)[0];
      case 8:
        return Pointer<Uint64>.fromAddress(buffer.address + offset)
            .asTypedList(1)[0];
      default:
        throw MemException(
            "Invalid byte count for reading int from buffer: $byteCnt");
    }
  } else {
    // the offset not aligned - copying byte by byte
    final bytes = Uint8List(byteCnt);
    for (var i = 0; i < byteCnt; i++) {
      bytes[i] = buffer[offset + i];
    }
    return fromBytesAsUnsigned(bytes);
  }
}