bufr/src/main/java/ucar/nc2/iosp/bufr/BufrNumbers.java
private static int int4(int a, int b, int c, int d) {
    // all bits set to ones
    if (a == 0xff && b == 0xff && c == 0xff && d == 0xff)
      return UNDEFINED;

    return (1 - ((a & 128) >> 6)) * ((a & 127) << 24 | b << 16 | c << 8 | d);
  }
private static int int4(int a, int b, int c, int d) {
    // all bits set to ones
    if (a == 0xff && b == 0xff && c == 0xff && d == 0xff)
      return UNDEFINED;

    return (1 - ((a & 128) >> 6)) * ((a & 127) << 24 | b << 16 | c << 8 | d);
  }
Convert 4 bytes into a signed integer.

@param a
@param b
@param c
@param d
@return int