# 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.
#

flags[1] scanningMode 'grib2/tables/[tablesVersion]/3.4.table' : edition_specific,no_copy ;

# Note our flagbit numbers go from 7 to 0, while WMO convention is from 1 to 8
flagbit iScansNegatively(scanningMode,7) : dump;   # WMO bit 1
flagbit jScansPositively(scanningMode,6) : dump;   # WMO bit 2
flagbit jPointsAreConsecutive(scanningMode,5) : dump;
flagbit alternativeRowScanning(scanningMode,4) = 0 : edition_specific,dump;

if (jPointsAreConsecutive) {
    alias numberOfRows=Ni;
    alias numberOfColumns=Nj;
} else {
    alias numberOfRows=Nj;
    alias numberOfColumns=Ni;
}

alias geography.iScansNegatively=iScansNegatively;
alias geography.jScansPositively=jScansPositively;
alias geography.jPointsAreConsecutive=jPointsAreConsecutive;

transient iScansPositively = !iScansNegatively : constraint;

flagbit scanningMode5(scanningMode,3) = 0: read_only;
flagbit scanningMode6(scanningMode,2) = 0: read_only;
flagbit scanningMode7(scanningMode,1) = 0: read_only;
flagbit scanningMode8(scanningMode,0) = 0: read_only;

meta swapScanningX change_scanning_direction( values,Ni,Nj,
                 iScansNegatively,jScansPositively,
                 xFirst,xLast,x) : edition_specific,hidden,no_copy;
alias swapScanningLon = swapScanningX;

meta swapScanningY change_scanning_direction( values,Ni,Nj,
                 iScansNegatively,jScansPositively,
                 yFirst,yLast,y) : edition_specific,hidden,no_copy;
alias swapScanningLat = swapScanningY;
