package gov.nasa.gsfc.spdf.cdfj; import java.nio.ByteBuffer; /** * Class for modelling the Global Descriptor Record (GDR). * @see https://spdf.gsfc.nasa.gov/pub/software/cdf/doc/cdf371/cdf37ifd.pdf section 2.3. * @author jbf */ public class GDR { ByteBuffer record = ByteBuffer.allocate(8 + 4 + 8 + 8 + 8 + 8 + 4 + 4 + 4 + 4 + 4 + 8 + 4 + 4 + 4); // see Figure 2.5 protected long position; long zVDRHead; long aDRHead; long eof; int numAttr; int nzVars; int lastLeapSecondId; /** * Signed 8-byte integer, big-endian byte ordering. The file offset of the * first zVariable Descriptor Record (zVDR). The first zVDR contains a file * offset to the next zVDR and so on. A zVDR will exist for each zVariable * in the CDF. Because zVariables were not supported by CDF until CDF V2.2, * prior to CDF V2.2 this field is undefined. Beginning with CDF V2.2 this * field will contain either a file offset to the first zVDR or * 0x0000000000000000 if the CDF contains no zVariables. The last zVDR will * always contain 0x0000000000000000 for the file offset of the next zVDR * (to indicate the end of the zVDRs * @param l */ public void setZVDRHead(long l) { zVDRHead = l; } /** * Signed 8-byte integer, big-endian byte ordering.The file offset of the * first Attribute Descriptor Record (ADR). The first ADR contains a file * offset to the next ADR and so on. An ADR will exist for each attribute * in the CDF. This field will contain 0x0000000000000000 if the CDF * contains no attributes. Beginning with CDF V2.1 the last ADR will * contain a file offset of 0x0000000000000000 for the file offset of * the next ADR (to indicate the end of the ADRs). * @param l */ public void setADRHead(long l) { aDRHead = l; } /** * Signed 8-byte integer, big-endian byte ordering.The end-of-file (EOF) * position in the dotCDF file. This is the file offset of the byte that * is one beyond the last byte of the last internal record. (This value is * also the total number of bytes used in the dotCDF file.) * * @param l */ public void setEof(long l) { eof = l; } /** * Signed 4-byte integer, big-endian byte ordering.The number of attributes * in the CDF. This will correspond to the number of ADRs in the dotCDF * file. * @param n */ public void setNumAttr(int n) { numAttr = n; } /** * Signed 4-byte integer, big-endian byte ordering.The number of zVariables * in the CDF. This will correspond to the number of zVDRs in the dotCDF * file. * @param n */ public void setNzVars(int n) { nzVars = n; } /** * Signed 4-byte integer, big-endian byte ordering.The date of the last * entry in the leap secondtable (in YYYYMMDD form). It is negative one * (-1) for the previous version.A value of zero (0) is also accepted, which * means a CDF was not created based on a leap second table. This field is * applicable to CDFs with CDF_TIME_TT2000 data type * @param n */ public void setLastLeapSecondId(int n) { lastLeapSecondId = n; } public ByteBuffer get() { record.position(0); record.putLong((long) (record.capacity())); record.putInt(2); record.putLong(0); // no rvars record.putLong(zVDRHead); record.putLong(aDRHead); record.putLong(eof); record.putInt(0); // no rvars record.putInt(numAttr); record.putInt(-1); record.putInt(0); record.putInt(nzVars); record.putLong(0); record.putInt(0); record.putInt(lastLeapSecondId); record.putInt(0); record.position(0); return record; } public int getSize() { return record.limit(); } }