Ubuntu Manpage: pdstemplates.c - Functions for GRIB2 Product Definition Templates used in Section 4

NAME

       pdstemplates.c - Functions for GRIB2 Product Definition Templates used in Section 4 - the Product
       Definition Section (PDS).

SYNOPSIS

       #include 'grib2_int.h'

   Functions
       gtemplate * extpdstemplate (g2int number, g2int *list)
           This subroutine generates the remaining octet map for a given Product Definition Template, if
           required.
       int g2c_get_pds_template (int pds_template_num, int *maplen, int *map, int *needext)
           Get PDS template information.
       int g2c_get_pds_template_extension (int pds_template_num, int *template, int *extlen, int *ext)
           Get pds template extension information.
       static g2int getpdsindex (g2int number)
           This function returns the index of specified Product Definition Template in array templates.
       gtemplate * getpdstemplate (g2int number)
           This subroutine returns PDS template information for a specified Product Definition Template.

   Variables
       static const struct pdstemplate templatespds [G2C_MAX_PDS_TEMPLATE]
           Data for struct for PDS template.

Detailed Description

Functions for GRIB2 Product Definition Templates used in Section 4 - the Product Definition Section
(PDS).

Each Template has three parts:

1. The number of entries in the template (mappdslen).

2. A map of the template (mappds), which contains the number of octets in which to pack each of the
template values.

3. A logical value (needext) that indicates whether the Template needs to be extended. In some cases the
number of entries in a template can vary depending upon values specified in the 'static' part of the
template. (See Template 4.3 as an example).

Note
Array mappds contains the number of octets in which the corresponding template values will be stored.
A negative value in mappds is used to indicate that the corresponding template entry can contain
negative values. This information is used later when packing (or unpacking) the template data values.
Negative data values in GRIB are stored with the left most bit set to one, and a negative number of
octets value in mappds[] indicates that this possibility should be considered. The number of octets
used to store the data value in this case would be the absolute value of the negative value in
mappds.

Program History Log
Date Programmer Comments 2001-06-28 Gilbert Initial 2009-01-14 Vuong Changed structure
name template to gtemplate 2009-12-15 Vuong Added Product Definition Templates 4.31, 4.15
2010-08-03 Vuong Added Product Definition Template 4.42 and 4.43 2010-12-08 Vuong Corrected
Product Definition Template 4.42 and 4.43 2012-03-29 Vuong Added Templates
4.44,4.45,4.46,4.47,4.48,4.50, 4.51,4.91,4.32 and 4.52 2013-08-05 Vuong Corrected 4.91 and added
Templates 4.33,4.34,4.53,4.54 2015-10-07 Vuong Added Templates 4.57, 4.60, 4.61 and allow a
forecast time to be negative 2022-10-18 Hartnett Added g2c_get_pds_template() and
g2c_get_pds_template_extension(). 2024-09-09 Stahl Added extension for Template 4.35 2024-12-04
Stahl Added 55 missing templates, including those from July 2024 WMO updates.

Author
Stephen Gilbert

Date
2001-06-28

Definition in file pdstemplates.c.

Function Documentation

gtemplate * extpdstemplate (g2int number, g2int * list)
This subroutine generates the remaining octet map for a given Product Definition Template, if required.
Some Templates can vary depending on data values given in an earlier part of the Template, and it is
necessary to know some of the earlier entry values to generate the full octet map of the Template.

This function allocates memory in the ext field of the gtemplate struct. This memory must be freed by the
caller.

Parameters
number number of the Product Definition Template 4.NN that is being requested.
list The list of values for each entry in the the Product Definition Template.

Returns
Pointer to the returned template struct. Returns NULL pointer if template not found.

Author
Stephen Gilbert

Date
2000-05-11

Definition at line 553 of file pdstemplates.c.

References getpdsindex(), and getpdstemplate().

Referenced by g2_addfield(), g2_unpack4(), and g2c_get_pds_template_extension().

int g2c_get_pds_template (int pds_template_num, int * maplen, int * map, int * needext)
Get PDS template information. The PDS template consists of a template map, its length, and, for some
templates, an extra extension map, and its length. If an extension is needed, use
g2c_get_pds_template_extension() to get it.

Parameters
pds_template_num The PDS template number.
maplen Pointer that gets the length of the map. Ignored if NULL.
map Pointer that gets the map as an array of int. Memory must be allocated by caller. Ignored if
NULL.
needext Pointer that a non-zero value if an extension to this template is needed. Ignored if NULL.

Returns

• G2C_NOERROR No error.

• G2C_ENOTEMPLATE Template not found.

Author
Ed Hartnett

Date
10/18/22

Definition at line 1806 of file pdstemplates.c.

References G2C_ENOTEMPLATE, G2C_MAX_PDS_TEMPLATE, G2C_NOERROR, and templatespds.

Referenced by g2c_rw_section4_metadata().

int g2c_get_pds_template_extension (int pds_template_num, int * template, int * extlen, int * ext)
Get pds template extension information.

Parameters
pds_template_num The pds template number.
template Pointer to array that contains the template values.
extlen Pointer that gets the length of the extension. Ignored if NULL.
ext Pointer that gets template extension array, if there is one. Memory must be allocated by the
caller. Ignored if NULL.

Returns

• G2C_NOERROR No error.

• G2C_EINVAL Invalid input.

• G2C_ENOTEMPLATE Template not found.

• G2C_ENOMEM Out of memory.

Author
Ed Hartnett

Date
10/16/22

Definition at line 1731 of file pdstemplates.c.

References gtemplate::ext, gtemplate::extlen, extpdstemplate(), G2C_EINVAL, G2C_ENOMEM, G2C_ENOTEMPLATE,
G2C_MAX_PDS_TEMPLATE, G2C_NOERROR, and templatespds.

static g2int getpdsindex (g2int number) [static]
This function returns the index of specified Product Definition Template in array templates.

Parameters
number The number of the Product Definition Template that is being requested.

Returns
Index of PDT in array templates, if template exists. -1, otherwise.

Author
Stephen Gilbert

Date
2001-06-28

Definition at line 469 of file pdstemplates.c.

References G2C_MAX_PDS_TEMPLATE, getpdsindex(), and templatespds.

Referenced by extpdstemplate(), getpdsindex(), and getpdstemplate().

gtemplate * getpdstemplate (g2int number)
This subroutine returns PDS template information for a specified Product Definition Template. The number
of entries in the template is returned along with a map of the number of octets occupied by each entry.
Also, a flag is returned to indicate whether the template would need to be extended.

This function allocates memory for the gtemplate struct, which must be freed by the caller.

Parameters
number the number of the Product Definition Template that is being requested.

Returns
Pointer to the returned template struct. Returns NULL pointer if template not found.

Author
Stephen Gilbert

Date
2000-05-11

Definition at line 504 of file pdstemplates.c.

References getpdsindex(), and templatespds.

Referenced by extpdstemplate(), g2_addfield(), and g2_unpack4().

Variable Documentation

   const struct pdstemplate templatespds[G2C_MAX_PDS_TEMPLATE] [static]
       Data for struct for PDS template.

       Definition at line 59 of file pdstemplates.c.

       Referenced    by    g2c_get_pds_template(),    g2c_get_pds_template_extension(),    getpdsindex(),    and
       getpdstemplate().

Author

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NCEPLIBS-g2c                                      Version 2.1.0                                pdstemplates.c(3)