eccodes/definitions/grib1/data.grid_simple_matrix.def

# (C) Copyright 2005- ECMWF.

#used in packing
constant constantFieldHalfByte=0;

# moved here to allow different bitsPerValue in second order packing
unsigned[1] bitsPerValue : dump ;
alias numberOfBitsContainingEachPackedValue = bitsPerValue;

unsigned[2] octetAtWichPackedDataBegins;
flags[1] extendedFlag "grib1/11-2.table";

flagbit matrixOfValues(extendedFlag,3) : dump;
flagbit secondaryBitmapPresent(extendedFlag,2) : dump;
flagbit secondOrderOfDifferentWidth(extendedFlag,1) : dump;

alias secondOrderValuesDifferentWidths = secondOrderOfDifferentWidth;
alias secondaryBitMap=secondaryBitmapPresent;

unsigned[2] NR : dump;
alias firstDimension = NR;

unsigned[2] NC : dump;
alias secondDimension = NC;

flags[1] coordinateFlag1 "grib1/12.table" : dump;
alias firstDimensionCoordinateValueDefinition = coordinateFlag1;

unsigned[1] NC1 : dump;
alias numberOfCoefficientsOrValuesUsedToSpecifyFirstDimensionCoordinateFunction = NC1;


flags[1] coordinateFlag2 "grib1/12.table" : dump;
alias secondDimensionCoordinateValueDefinition = coordinateFlag2;

unsigned[1] NC2 : dump;
alias numberOfCoefficientsOrValuesUsedToSpecifySecondDimensionCoordinateFunction = NC2;

flags[1] physicalFlag1    "grib1/13.table" : dump;
alias firstDimensionPhysicalSignificance = physicalFlag1; # TODO: Check if grib1 and 2 table are the same


flags[1] physicalFlag2    "grib1/13.table" : dump;
alias secondDimensionPhysicalSignificance = physicalFlag2; # TODO: Check if grib1 and 2 table are the same

ibmfloat coefsFirst[NC1] : dump;

ibmfloat coefsSecond[NC2] : dump;

alias data.coefsFirst = coefsFirst;
alias data.coefsSecond=coefsSecond;

position offsetBeforeData;

if(matrixOfValues == 0)
{
	constant matrixBitmapsPresent  = 0;
	position offsetBeforeData;

	if(bitmapPresent) {

		# For grib1 -> grib2
		constant bitMapIndicator = 0;

        meta codedValues data_g1simple_packing (           
               section4Length,
               offsetBeforeData,
               offsetSection4,
               unitsFactor,
               unitsBias,
               changingPrecision,
               numberOfCodedValues,
               bitsPerValue,
               referenceValue,
               binaryScaleFactor,
               decimalScaleFactor,
               optimizeScaleFactor,
               halfByte,
               packingType,
               grid_ieee
        ) : read_only;
            alias data.packedValues = codedValues;
        meta values data_apply_bitmap(codedValues,bitmap,missingValue,binaryScaleFactor) : dump;
        # See GRIB-262: The octetAtWichPackedDataBegins cannot be set to a value bigger than 65535!
        #               This is historic stuff which no longer applies
        # when(changed(values)) {set octetAtWichPackedDataBegins=numberOfCodedValues;}
	} else {
		# For grib1 -> grib2
		constant bitMapIndicator = 255;

        meta values data_g1simple_packing(
              section4Length,
              offsetBeforeData,
              offsetSection4,
              unitsFactor,
              unitsBias,
              changingPrecision,
              numberOfCodedValues,
              bitsPerValue,
              referenceValue,
              binaryScaleFactor,
              decimalScaleFactor,
              optimizeScaleFactor,
              halfByte
        ) : dump;

        alias data.packedValues = values;
	}
} else {
	#if(secondaryBitmapPresent == 0) { meta error not_implemented(); }

	constant matrixBitmapsPresent  = 1;
	constant bitMapIndicator = 0;

# From GRIBEX:
#
#            !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
#            !                                                !
#            ! This is the WMO definition, but it is entirely !
#            ! inadequate when secondary bit maps are present !
#            ! eg 3x3 global grid with a matrix of values     !
#            ! 12x26 at each point. This gives a bit map with !
#            ! a length of 285480 octets which cannot be given!
#            ! in 16 bits.                                    !
#            !                                                !
#            ! ECMWF uses the following definition  for its   !
#            ! wave model data.                               !
#            ! N - Number of secondary bit maps               !
#            !     (ie the number of points which are 'not    !
#            !      missing').                                !
#            !     This definition will accommodate a 1x1     !
#            !     degree global grid.                        !
#            !                                                !
#            !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
#

	  constant datumSize             = NC*NR;
	  transient secondaryBitmapsCount = octetAtWichPackedDataBegins*datumSize; #
	  transient secondaryBitmapsSize  = secondaryBitmapsCount/8;

	  #alias numberOfDataPoints = secondaryBitmapsCount; # grib 1 -> 2

	  position offsetBBitmap;

	  meta secondaryBitmaps g1bitmap(
			  dummy,
              missingValue,
              offsetBBitmap,
              secondaryBitmapsSize,
              dummy) : read_only;

		position  offsetBeforeData;

	  meta codedValues data_g1simple_packing(
               section4Length,
               offsetBeforeData,
               offsetSection4,
               unitsFactor,
               unitsBias,
               changingPrecision,
               numberOfCodedValues,
               bitsPerValue,
               referenceValue,
               binaryScaleFactor,
               decimalScaleFactor,
               optimizeScaleFactor,
               halfByte
            ) : read_only;

	  alias data.packedValues = codedValues;

	  constant expandBy = NC*NR;
	  meta secondaryBitmap  data_g1secondary_bitmap(bitmap,secondaryBitmaps,missingValue,expandBy,octetAtWichPackedDataBegins);

	  meta values data_apply_bitmap(codedValues,secondaryBitmap,missingValue,binaryScaleFactor) : dump;

}
meta packingError simple_packing_error(bitsPerValue,binaryScaleFactor,decimalScaleFactor,referenceValue,ibm) : no_copy;
meta numberOfCodedValues number_of_coded_values(bitsPerValue,offsetBeforeData,offsetAfterData,halfByte,numberOfValues) : dump;
 
template statistics "common/statistics_grid.def";