Unpack Section 7 (Data Section) as defined in GRIB Edition 2. More...

#include <stdio.h>
#include <stdlib.h>
#include <memory.h>
#include <string.h>
#include "grib2.h"

Functions
int	comunpack (unsigned char , g2int, g2int, g2int , g2int, g2float *)
	This subroutine unpacks a data field that was packed using a complex packing algorithm as defined in the GRIB2 documention, using info from the GRIB2 Data Representation Template 5.2 or Template 5.3. More...

g2int	g2_unpack7 (unsigned char cgrib, g2int iofst, g2int igdsnum, g2int igdstmpl, g2int idrsnum, g2int idrstmpl, g2int ndpts, g2float **fld)
	This subroutine unpacks Section 7 (Data Section) as defined in GRIB Edition 2. More...

g2int	jpcunpack (unsigned char , g2int, g2int , g2int, g2float *)
	This subroutine unpacks a data field that was packed into a JPEG2000 code stream using info from the GRIB2 Data Representation Template 5.40 or 5.40000. More...

g2int	pngunpack (unsigned char , g2int, g2int , g2int, g2float *)
	This subroutine unpacks a data field that was packed into a PNG image format using info from the GRIB2 Data Representation Template 5.41 or 5.40010. More...

g2int	simunpack (unsigned char , g2int , g2int, g2float *)
	This subroutine unpacks a data field that was packed using a simple packing algorithm as defined in the GRIB2 documention, using info from the GRIB2 Data Representation Template 5.0. More...

g2int	specunpack (unsigned char , g2int , g2int, g2int, g2int, g2int, g2float *)
	This subroutine unpacks a spectral data field that was packed using the complex packing algorithm for spherical harmonic data as defined in the GRIB2 documention, using info from the GRIB2 Data Representation Template 5.51. More...

Detailed Description

Unpack Section 7 (Data Section) as defined in GRIB Edition 2.

Author: Stephen Gilbert

Date: 2002-10-31

Definition in file g2_unpack7.c.

Function Documentation

◆ comunpack()

int comunpack	(	unsigned char *	cpack,
		g2int	lensec,
		g2int	idrsnum,
		g2int *	idrstmpl,
		g2int	ndpts,
		g2float *	fld
	)

This subroutine unpacks a data field that was packed using a complex packing algorithm as defined in the GRIB2 documention, using info from the GRIB2 Data Representation Template 5.2 or Template 5.3.

Supports GRIB2 complex packing templates with or without spatial differences (i.e. DRTs 5.2 and 5.3).

Program History Log

Date	Programmer	Comments
2002-10-29	Gilbert	Initial
2004-12-16	Gilbert	Added test (from Arthur Taylor/MDL) verifying group widths/lengths

Parameters

cpack	pointer to the packed data field.
lensec	length of section 7 (used for error checking).
idrsnum	Data Representation Template number. Must equal 2 or 3.
idrstmpl	pointer to the array of values for Data Representation Template 5.2 or 5.3
ndpts	The number of data values to unpack
fld	Contains the unpacked data values. Must be allocated with at least ndpts * sizeof(g2float) bytes before calling this routine.

Returns: 0 for success, error code otherwise.

Author: Stephen Gilbert

Date: 2002-10-29

Definition at line 42 of file comunpack.c.

References gbit(), gbits(), int_power(), and rdieee().

Referenced by g2_unpack7().

◆ g2_unpack7()

g2int g2_unpack7	(	unsigned char *	cgrib,
		g2int *	iofst,
		g2int	igdsnum,
		g2int *	igdstmpl,
		g2int	idrsnum,
		g2int *	idrstmpl,
		g2int	ndpts,
		g2float **	fld
	)

This subroutine unpacks Section 7 (Data Section) as defined in GRIB Edition 2.

Program History Log

Date	Programmer	Comments
2002-10-31	Gilbert	Initial
2002-12-20	Gilbert	Added GDT info to arguments and added 5.51 processing.
2003-08-29	Gilbert	New templates using PNG and JPEG2000 algorithms/templates.
2004-11-29	Gilbert	JPEG2000 now allowed to use WMO Template 5.40 PNG allowed to use 5.41
2004-12-16	Taylor	Added check on comunpack return code.
2008-12-23	Wesley	Initialize Number of data points unpacked

Parameters

cgrib	char array containing Section 7 of the GRIB2 message
iofst	Bit offset of the beginning of Section 7 in cgrib.
igdsnum	Grid Definition Template Number (see Code Table 3.0) (Only used for DRS Template 5.51)
igdstmpl	Pointer to an integer array containing the data values for the specified Grid Definition Template (N=igdsnum). Each element of this integer array contains an entry (in the order specified) of Grid Definition Template 3.N. (Only used for DRS Template 5.51).
idrsnum	Data Representation Template Number (see Code Table 5.0)
idrstmpl	Pointer to an integer array containing the data values for the specified Data Representation Template (N=idrsnum). Each element of this integer array contains an entry (in the order specified) of Data Representation Template 5.N
ndpts	Number of data points unpacked and returned.
fld	Pointer to a float array containing the unpacked data field.

Returns

0 no error
2 Not section 7
4 Unrecognized Data Representation Template
5 need one of GDT 3.50 through 3.53 to decode DRT 5.51
6 memory allocation error
7 corrupt section 7.

Author: Stephen Gilbert

Date: 2002-10-31

Definition at line 65 of file g2_unpack7.c.

References comunpack(), gbit(), jpcunpack(), pngunpack(), rdieee(), simunpack(), and specunpack().

Referenced by g2_getfld().

◆ jpcunpack()

g2int jpcunpack	(	unsigned char *	cpack,
		g2int	len,
		g2int *	idrstmpl,
		g2int	ndpts,
		g2float *	fld
	)

This subroutine unpacks a data field that was packed into a JPEG2000 code stream using info from the GRIB2 Data Representation Template 5.40 or 5.40000.

Parameters

cpack	The packed data field (character*1 array).
len	length of packed field cpack.
idrstmpl	Pointer to array of values for Data Representation Template 5.40 or 5.40000.
ndpts	The number of data values to unpack.
fld	Contains the unpacked data values.

Returns: 0 for success, 1 for memory allocation error.

Author: Stephem Gilbert

Date: 2003-08-27

Definition at line 31 of file jpcunpack.c.

References dec_jpeg2000(), int_power(), and rdieee().

Referenced by g2_unpack7().

◆ pngunpack()

g2int pngunpack	(	unsigned char *	cpack,
		g2int	len,
		g2int *	idrstmpl,
		g2int	ndpts,
		g2float *	fld
	)

This subroutine unpacks a data field that was packed into a PNG image format using info from the GRIB2 Data Representation Template 5.41 or 5.40010.

Parameters

cpack	The packed data field (character*1 array).
len	length of packed field cpack().
idrstmpl	Pointer to array of values for Data Representation Template 5.41 or 5.40010.
ndpts	The number of data values to unpack.
fld	Contains the unpacked data values.

Returns: 0 for success, 1 for memory allocation error.

Author: Stephen Gilbert

Date: 2003-08-27

Definition at line 30 of file pngunpack.c.

References dec_png(), gbits(), int_power(), and rdieee().

Referenced by g2_unpack7().

◆ simunpack()

g2int simunpack	(	unsigned char *	cpack,
		g2int *	idrstmpl,
		g2int	ndpts,
		g2float *	fld
	)

This subroutine unpacks a data field that was packed using a simple packing algorithm as defined in the GRIB2 documention, using info from the GRIB2 Data Representation Template 5.0.

Parameters

cpack	pointer to the packed data field.
idrstmpl	pointer to the array of values for Data Representation Template 5.0.
ndpts	The number of data values to unpack.
fld	Contains the unpacked data values. fld must be `* allocated with at least ndpts * sizeof(g2float) bytes before calling this routine.

Returns: 0 for success, error code otherwise.

Author: Stephen Gilbert

Date: 2002-10-29

Definition at line 26 of file simunpack.c.

References gbits(), int_power(), and rdieee().

Referenced by g2_unpack7().

◆ specunpack()

g2int specunpack	(	unsigned char *	cpack,
		g2int *	idrstmpl,
		g2int	ndpts,
		g2int	JJ,
		g2int	KK,
		g2int	MM,
		g2float *	fld
	)

This subroutine unpacks a spectral data field that was packed using the complex packing algorithm for spherical harmonic data as defined in the GRIB2 documention, using info from the GRIB2 Data Representation Template 5.51.

Parameters

cpack	pointer to the packed data field.
idrstmpl	pointer to the array of values for Data Representation Template 5.51.
ndpts	The number of data values to unpack (real and imaginary parts).
JJ	pentagonal resolution parameter.
KK	pentagonal resolution parameter.
MM	pentagonal resolution parameter.
fld	Contains the unpacked data values. fld must be allocated with at least ndpts * sizeof(g2float) bytes before calling this routine.

Returns: 0 for success, -3 for wrong type.

Author: Stephen Gilbert

Date: 2000-06-21

Definition at line 35 of file specunpack.c.

References gbits(), int_power(), and rdieee().

Referenced by g2_unpack7().

Functions

Detailed Description

Function Documentation

◆ comunpack()

Program History Log

◆ g2_unpack7()

Program History Log

◆ jpcunpack()

◆ pngunpack()

◆ simunpack()

◆ specunpack()