docs: public static byte[] dec(Pointer _s, final int _len) {
          int len = _len;
          byte[] sb = _s.buffer;
          int s = _s.start;
          int a = -1,b = -1,c = 0,d;
          
          byte[] ptrb = new byte[len];
          System.arraycopy(sb, s, ptrb, 0, len);
          int ptr = 0;
          int end = 0;
          int send = s + len;
  
          while(s < send) {
              while(sb[s] == '\r' || sb[s] == '\n') { s++; }
              if((a = b64_xtable[(int)sb[s+0]]) == -1) break;
              if((b = b64_xtable[(int)sb[s+1]]) == -1) break;
              if((c = b64_xtable[(int)sb[s+2]]) == -1) break;
              if((d = b64_xtable[(int)sb[s+3]]) == -1) break;
              ptrb[end++] = (byte)((a << 2) | (b >> 4));
              ptrb[end++] = (byte)((b << 4) | (c >> 2));
              ptrb[end++] = (byte)((c << 6) | d);
              s += 4;
          }
  
          if(a != -1 && b != -1) {
              if(s + 2 < send && sb[s+2] == '=')
                  ptrb[end++] = (byte)((a << 2) | (b >> 4));
              if(c != -1 && s + 3 < send && sb[s+3] == '=') {
                  ptrb[end++] = (byte)((a << 2) | (b >> 4));
                  ptrb[end++] = (byte)((b << 4) | (c >> 2));
              }
          }
          ptrb[end] = '\0';
          return ptrb;
      }