g2_unpack3.c - Unpack Section 3 (Grid Definition Section) of a GRIB2 message.

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NCEPLIBS-g2c                                      Version 2.1.0                                  g2_unpack3.c(3)

       Unpack Section 3 (Grid Definition Section) of a GRIB2 message.

       Author
           Stephen Gilbert

       Date
           2002-10-31

       Definition in file g2_unpack3.c.

g2intg2_unpack3(unsignedchar*cgrib,g2int*iofst,g2int**igds,g2int**igdstmpl,g2int*mapgridlen,g2int**ideflist,g2int*idefnum)
       Unpack Section 3 (Grid Definition Section) of a GRIB2 message.

   ProgramHistoryLog
       Date   Programmer   Comments    2002-10-31   Gilbert   Initial    2009-01-14   Vuong   Changed structure
       name template to gtemplate

       Parameterscgrib Char array ontaining Section 3 of the GRIB2 message.
           iofst Pointer to g2int which contains the bit offset for the beginning of Section 3 in cgrib.
           igds Pointer to a pointer which will get a pointer to memory allocated for the GDS array, of length
           5. The array will contain information read from the appropriate GRIB Grid Definition Section 3 for
           the field being returned.

           • igds[0] Source of grid definition (see Table 3.0).

           • igds[1] Number of grid points in the defined grid.

           • igds[2]  Number  of octets needed for each additional grid points definition. Used to define number
             of points in each row (or column) for non-regular grids. = 0, if using regular grid.

           • igds[3] Interpretation of list for optional points definition. (See Table 3.11)

           • igds[4] Grid Definition Template Number (see Table 3.1).

           igdstmpl Pointer a pointer to g2int, which will get a pointer to an  allocated  array  that  contians
           containing the data values from the Grid Definition Template specified by igds[4].
           mapgridlen  A  pointer  tat  gets  the number of elements in igdstmpl. i.e. number of entries in Grid
           Defintion Template specified by igds[4].
           ideflist (Used if igds[2] .ne. 0) Pointer to integer array  containing  the  number  of  grid  points
           contained in each row (or column).
           idefnum  (Used  if  igds[2] != 0.) A pointer that gets the number of entries in array ideflist - i.e.
           number of rows (or columns) for which optional grid points are defined.

       Returns

           • G2_NO_ERROR No error.

           • G2_UNPACK_BAD_SEC Array passed had incorrect section number.

           • G2_UNPACK3_BAD_GDT message contains an undefined Grid Definition Template.

           • G2_UNPACK_NO_MEM Memory allocation error.

       Author
           Stephen Gilbert

       Date
           2002-10-31

       Definition at line 62 of file g2_unpack3.c.

       References  gtemplate::ext,  extgridtemplate(),   gtemplate::extlen,   G2_NO_ERROR,   G2_UNPACK3_BAD_GDT,
       G2_UNPACK_BAD_SEC,     G2_UNPACK_NO_MEM,     gbit(),    gbits(),    getgridtemplate(),    gtemplate::map,
       gtemplate::maplen, and gtemplate::needext.

       Referenced by g2_getfld(), getdim(), and getpoly().

       g2_unpack3.c - Unpack Section 3 (Grid Definition Section) of a GRIB2 message.

       #include 'grib2_int.h'
       #include <stdio.h>
       #include <stdlib.h>

   Functionsg2intg2_unpack3 (unsigned char *cgrib, g2int *iofst, g2int **igds, g2int **igdstmpl, g2int *mapgridlen,
           g2int **ideflist, g2int *idefnum)
           Unpack Section 3 (Grid Definition Section) of a GRIB2 message.