grib/src/main/java/ucar/nc2/grib/GribNumbers.java
public static int countBits(byte[] bitmap) {
    int bits = 0;
    for (byte b : bitmap) {
      short s = DataType.unsignedByteToShort(b);
      bits += Long.bitCount(s);
    }
    return bits;
  }
public static int countBits(byte[] bitmap) {
    int bits = 0;
    for (byte b : bitmap) {
      short s = DataType.unsignedByteToShort(b);
      bits += Long.bitCount(s);
    }
    return bits;
  }
count number of bits on in bitmap