# Copyright 2005-2018 ECMWF.
#
# This software is licensed under the terms of the Apache Licence Version 2.0
# which can be obtained at http://www.apache.org/licenses/LICENSE-2.0.
# 
# In applying this licence, ECMWF does not waive the privileges and immunities granted to it by
# virtue of its status as an intergovernmental organisation nor does it submit to any jurisdiction.
#

# GRID DEFINITION quasi-regular latitude/longitude grid
# grib 1 -> 2
constant gridDefinitionTemplateNumber     = 0;

unsigned[2] NRj : can_be_missing,dump;

unsigned[2] numberOfPointsAlongAMeridian : can_be_missing,dump;
alias Nj  = numberOfPointsAlongAMeridian;

# Latitudes and Longitudes of the first and the last points
# Resolution and component flags
include "grib1/grid_first_last_resandcomp.def";

unsigned[2] iDirectionIncrement : can_be_missing;
unsigned[2] jDirectionIncrement : can_be_missing;
alias Dj = jDirectionIncrement;
alias Di = iDirectionIncrement;

# for change_scanning_direction
alias yFirst=latitudeOfFirstGridPointInDegrees;
alias yLast=latitudeOfLastGridPointInDegrees;
alias xFirst=longitudeOfFirstGridPointInDegrees;
alias xLast=longitudeOfLastGridPointInDegrees;

include "grib1/scanning_mode.def";

#  Lar1 - latitude of first grid point of reference domain
signed[3] Lar1 :  edition_specific;
meta geography.Lar1InDegrees scale(latitudeOfFirstGridPointOfReferenceDomain,oneConstant,grib1divider,truncateDegrees) :dump;
alias La1 = Lar1;

#  Lor1 - longitude of first grid point of reference domain
signed[3] Lor1  : edition_specific;
meta geography.Lor1InDegrees scale(longitudeOfFirstGridPointOfReferenceDomain,oneConstant,grib1divider,truncateDegrees) : dump;
alias Lo1 = Lor1;

#  Lar2 - latitude of last grid point of reference domain
signed[3] Lar2 :  edition_specific;
meta geography.Lar2InDegrees scale(latitudeOfLastGridPointOfReferenceDomain,oneConstant,grib1divider,truncateDegrees) : dump;
alias La2 = Lar2;

#  Lor2 - longitude of last grid point of reference domain
signed[3] Lor2 ;
meta geography.Lor2InDegrees scale(longitudeOfLastGridPointOfReferenceDomain,oneConstant,grib1divider,truncateDegrees) : dump;
alias Lo2 = Lor2;

meta  geography.jDirectionIncrementInDegrees latlon_increment(ijDirectionIncrementGiven,jDirectionIncrement,
  jScansPositively,
  latitudeOfFirstGridPointInDegrees,latitudeOfLastGridPointInDegrees,
  numberOfPointsAlongAMeridian,oneConstant,grib1divider,0) : can_be_missing,dump;
#transient DjInMicrodegrees = times(jDirectionIncrement,thousand);

meta  geography.iDirectionIncrementInDegrees latlon_increment(ijDirectionIncrementGiven,iDirectionIncrement,
  iScansPositively,
  longitudeOfFirstGridPointInDegrees,longitudeOfLastGridPointInDegrees,
  Ni,oneConstant,grib1divider,1) : can_be_missing,dump;
#meta DiInMicrodegrees times(iDirectionIncrement,thousand);

alias latitudeFirstInDegrees = latitudeOfFirstGridPointInDegrees;
alias longitudeFirstInDegrees = longitudeOfFirstGridPointInDegrees;

alias latitudeLastInDegrees  = latitudeOfLastGridPointInDegrees;
alias longitudeLastInDegrees = longitudeOfLastGridPointInDegrees;
alias DiInDegrees = iDirectionIncrementInDegrees;
alias DjInDegrees = jDirectionIncrementInDegrees;

meta numberOfDataPoints number_of_points(Ni,Nj,PLPresent,pl) : dump;
alias numberOfPoints=numberOfDataPoints;
meta numberOfValues number_of_values(values,bitsPerValue,numberOfDataPoints,bitmapPresent,bitmap,numberOfCodedValues) : dump;
#alias ls.valuesCount=numberOfValues;

if(missing(Ni)){
   iterator latlon_reduced(numberOfPoints,missingValue,values,
      latitudeFirstInDegrees,longitudeFirstInDegrees,
      latitudeLastInDegrees,loLast,
      Nj,DjInDegrees,pl);
   nearest latlon_reduced(values,radius,Nj,pl);
} else {
   iterator latlon(numberOfPoints,missingValue,values,longitudeFirstInDegrees,iInc ,
                   Ni,Nj,iScansNegatively ,
                   latitudeFirstInDegrees,DjInDegrees,jScansPositively );
   nearest regular(values,radius,Ni,Nj);
}
meta latLonValues latlonvalues(values);
alias latitudeLongitudeValues=latLonValues;
meta latitudes latitudes(values,0);
meta longitudes longitudes(values,0);
meta distinctLatitudes latitudes(values,1);
meta distinctLongitudes longitudes(values,1);

# END   1/grid_definition.latitude_longitude_grid ----------------------------------------------------------------------
