June 01, 2009
                                                           W/NP11:SAG

g2lib Library.

This library contains Fortran 90 decoder/encoder
routines for GRIB edition 2, as well as indexing/searching
utility routines.  The user API for the GRIB2 routines
is described in file "grib2.doc".

Some Fortran routines call "C" functions, which must
follow a specific symbol naming convention used by your
machine/loader to be linked successfully.
If you are having trouble linking to the C routines
in this library, please make sure the appropriate 
machine is defined as an option in the CFLAGS
variable in the makefile.  See the first few lines
of the makefile for valid options.
Recompile the library.

We have added support for PNG and JPEG2000 image compression
algorithms within the GRIB2 standard.  If you would like
to compile this library to utilize these GRIB2 Templates,
make sure that -DUSE_PNG and -DUSE_JPEG2000 are specified
in the FDEFS variable in the makefile.  You will also need
to download and install the external libraries listed below,
if they are not already installed on your system.

If you do not wish to bother with the external libs and
don't need PNG and JPEG2000 support, you can remove the
-DUSE_PNG and -DUSE_JPEG2000 flags from the FDEFS variable 
in the makefile.


-------------------------------------------------------------------------------

     External Libraries:

libjasper.a - This library is a C implementation of the JPEG-2000 Part-1 
              standard (i.e., ISO/IEC 15444-1).  This library is required
              if JPEG2000 support in GRIB2 is desired.  If not, remove
              the -DUSE_JPEG2000 option from the FDEFS variable 
              in the makefile.

              Download version jasper-1.900.1 from the JasPer Project's
              home page, http://www.ece.uvic.ca/~mdadams/jasper/.
        
              More information about JPEG2000 can be found at 
              http://www.jpeg.org/JPEG2000.html.

libpng.a      This library is a C implementation of the Portable Network
              Graphics PNG image compression format.  This library is required
              if PNG support in GRIB2 is desired.  If not, remove
              the -DUSE_PNG option from the FDEFS variable
              in the makefile.

              If not already installed on your system, download version 
              libpng-1.2.35 from http://www.libpng.org/pub/png/libpng.html.

              More information about PNG can be found at 
              http://www.libpng.org/pub/png/.

libz.a        This library contains compression/decompression routines
              used by libpng.a for PNG image compression support. 
              This library is required if PNG support in GRIB2 is desired.  
              If not, remove the -DUSE_PNG option from the FDEFS variable
              in g2lib/makefile.

              If not already installed on your system, download version 
              zlib-1.2.3 from http://www.gzip.org/zlib/.

-------------------------------------------------------------------------------

A note about routine MOVA2I:

Some routines in this library call subroutine MOVA2I, which is included in 
our W3LIB library containing the GRIB1 decoder/encoder routines.  If you
are using this library without libw3.a, you will need to compile mova2i.c 
(included in this distribution) so it can be added to libg2.a.  Just add
the line:

        $(LIB)(mova2i.o) \

to the list of routines in the makefile.