NAME

       g2_unpack3.c - Unpack Section 3 (Grid Definition Section) as defined in GRIB Edition 2.

SYNOPSIS

       #include <stdio.h>
       #include <stdlib.h>
       #include 'grib2.h'

   Functions
       g2int g2_unpack3 (unsigned char *cgrib, g2int *iofst, g2int **igds, g2int **igdstmpl,
           g2int *mapgridlen, g2int **ideflist, g2int *idefnum)
           This routine unpacks Section 3 (Grid Definition Section) as defined in GRIB Edition 2.

Detailed Description

       Unpack Section 3 (Grid Definition Section) as defined in GRIB Edition 2.

       Author
           Stephen Gilbert

       Date
           2002-10-31

       Definition in file g2_unpack3.c.

Function Documentation

   g2int g2_unpack3 (unsigned char * cgrib, g2int * iofst, g2int ** igds, g2int ** igdstmpl,
       g2int * mapgridlen, g2int ** ideflist, g2int * idefnum)
       This routine unpacks Section 3 (Grid Definition Section) as defined in GRIB Edition 2.
       PROGRAM HISTORY LOG:

       • 2002-10-31 Gilbert

       • 2009-01-14 Vuong Changed structure name template to gtemplate

       Parameters
           cgrib Char array ontaining Section 3 of the GRIB2 message.
           iofst Bit offset for the beginning of Section 3 in cgrib.
           igds Contains information read from the appropriate GRIB Grid Definition Section 3 for
           the field being returned.

           • igds[0] Source of grid definition (see Code 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. (Code Table 3.11)

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

           igdstmpl - Pointer to integer array containing the data values for the specified Grid
           Definition Template (NN=igds[4]). Each element of this integer array contains an entry
           (in the order specified) of Grid Defintion Template 3.NN
           mapgridlen- Number of elements in igdstmpl[]. i.e. number of entries in Grid Defintion
           Template 3.NN (NN=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 ). (part of Section 3).
           idefnum (Used if igds[2] .ne. 0) The number of entries in array ideflist. i.e. number
           of rows (or columns) for which optional grid points are defined.

       Returns

           • 0 no error

           • 2 Not Section 3

           • 5 'GRIB' message contains an undefined Grid Definition Template.

           • 6 memory allocation error

       Author
           Stephen Gilbert

       Date
           2002-10-31

       Definition at line 53 of file g2_unpack3.c.

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

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

Author

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