cdm/src/main/java/ucar/nc2/iosp/LayoutSegmented.java
private int getMaxBytes(long start) {
    int segno = 0;
    while (start >= segMax[segno]) segno++;
    return (int) (segMax[segno] - start);
  }
private int getMaxBytes(long start) {
    int segno = 0;
    while (start >= segMax[segno]) segno++;
    return (int) (segMax[segno] - start);
  }
how many more bytes are in this segment ?