anchor.diff:              if (result >= 0) {
                   modulus = (modulus+1) % _BYTES_PER_ENCODED_BLOCK;
                   // https://groups.google.com/a/dartlang.org/d/msg/misc/6u9UNNLRjZw/YE9bV99lWyoJ
  -                ibitWorkArea = ((ibitWorkArea << _BITS_PER_ENCODED_BYTE) & 0xffffffff) | result;
  +                ibitWorkArea = ((ibitWorkArea << _BITS_PER_ENCODED_BYTE) & _MASK_INT) | result;
                   if (modulus == 0) {
                       buffer[outPos++] = ((ibitWorkArea >> 16) & 0xff);
                       buffer[outPos++] = ((ibitWorkArea >> 8) & 0xff);
  
positive.code: library base64_codec;
  
  import 'dart:math';
  import 'dart:typeddata';
  import 'dart:async';
  
  /**
  
negative.code:   /// LF seperator
    const int LF = 10;
  
    // mask to keep results from overlflowing an int on left shift
    //const int _MASK_INT =  0x3fffffff;
    const int _MASK_INT =  0xffffff;
  
  
    const _MAX_LENGTH= 64; // PEM line length
  
  