source: lmdz_wrf/WRFV3/external/io_grib2/g2lib/getgb2r.F @ 1

C-----------------------------------------------------------------------
      SUBROUTINE GETGB2R(LUGB,CINDEX,GFLD,IRET)
C$$$  SUBPROGRAM DOCUMENTATION BLOCK
C
C SUBPROGRAM: GETGB2R        READS AND UNPACKS A GRIB FIELD
C   PRGMMR: GILBERT          ORG: W/NP11     DATE: 02-01-15
C
C ABSTRACT: READ AND UNPACK SECTIONS 6 AND 7 FROM A GRIB2 MESSAGE.
C
C   This routine assumes that the "metadata" for this field
C   already exists in derived type gribfield.  Specifically,
C   it requires gfld%ibmap,gfld%ngrdpts,gfld%idrtnum,gfld%idrtmpl,
C   and gfld%ndpts.
C   
C   The decoded information for the selected GRIB field
C   is returned in a derived type variable, gfld.
C   Gfld is of type gribfield, which is defined
C   in module grib_mod, so users of this routine will need to include
C   the line "USE GRIB_MOD" in their calling routine.  Each component of the
C   gribfield type is described in the OUTPUT ARGUMENT LIST section below.
C
C PROGRAM HISTORY LOG:
C   95-10-31  IREDELL
C 2002-01-11  GILBERT     MODIFIED FROM GETGB1R TO WORK WITH GRIB2
C
C USAGE:    CALL GETGB2R(LUGB,CINDEX,GFLD,IRET)
C   INPUT ARGUMENTS:
C     LUGB         INTEGER UNIT OF THE UNBLOCKED GRIB DATA FILE
C     CINDEX       INDEX RECORD OF THE GRIB FIELD  ( SEE DOCBLOCK OF
C                  SUBROUTINE IXGB2 FOR DESCRIPTION OF AN INDEX RECORD.)
C   OUTPUT ARGUMENTS:
C     gfld - derived type gribfield ( defined in module grib_mod )
C            ( NOTE: See Remarks Section )
C        gfld%version = GRIB edition number ( currently 2 )
C        gfld%discipline = Message Discipline ( see Code Table 0.0 )
C        gfld%idsect() = Contains the entries in the Identification
C                        Section ( Section 1 )
C                        This element is actually a pointer to an array
C                        that holds the data.
C            gfld%idsect(1)  = Identification of originating Centre
C                                    ( see Common Code Table C-1 )
C                             7 - US National Weather Service
C            gfld%idsect(2)  = Identification of originating Sub-centre
C            gfld%idsect(3)  = GRIB Master Tables Version Number
C                                    ( see Code Table 1.0 )
C                             0 - Experimental
C                             1 - Initial operational version number
C            gfld%idsect(4)  = GRIB Local Tables Version Number
C                                    ( see Code Table 1.1 )
C                             0     - Local tables not used
C                             1-254 - Number of local tables version used
C            gfld%idsect(5)  = Significance of Reference Time (Code Table 1.2)
C                             0 - Analysis
C                             1 - Start of forecast
C                             2 - Verifying time of forecast
C                             3 - Observation time
C            gfld%idsect(6)  = Year ( 4 digits )
C            gfld%idsect(7)  = Month
C            gfld%idsect(8)  = Day
C            gfld%idsect(9)  = Hour
C            gfld%idsect(10)  = Minute
C            gfld%idsect(11)  = Second
C            gfld%idsect(12)  = Production status of processed data
C                                    ( see Code Table 1.3 )
C                              0 - Operational products
C                              1 - Operational test products
C                              2 - Research products
C                              3 - Re-analysis products
C            gfld%idsect(13)  = Type of processed data ( see Code Table 1.4 )
C                              0  - Analysis products
C                              1  - Forecast products
C                              2  - Analysis and forecast products
C                              3  - Control forecast products
C                              4  - Perturbed forecast products
C                              5  - Control and perturbed forecast products
C                              6  - Processed satellite observations
C                              7  - Processed radar observations
C        gfld%idsectlen = Number of elements in gfld%idsect().
C        gfld%local() = Pointer to character array containing contents
C                       of Local Section 2, if included
C        gfld%locallen = length of array gfld%local()
C        gfld%ifldnum = field number within GRIB message
C        gfld%griddef = Source of grid definition (see Code Table 3.0)
C                      0 - Specified in Code table 3.1
C                      1 - Predetermined grid Defined by originating centre
C        gfld%ngrdpts = Number of grid points in the defined grid.
C        gfld%numoct_opt = Number of octets needed for each
C                          additional grid points definition.
C                          Used to define number of
C                          points in each row ( or column ) for
C                          non-regular grids.
C                          = 0, if using regular grid.
C        gfld%interp_opt = Interpretation of list for optional points
C                          definition.  (Code Table 3.11)
C        gfld%igdtnum = Grid Definition Template Number (Code Table 3.1)
C        gfld%igdtmpl() = Contains the data values for the specified Grid
C                         Definition Template ( NN=gfld%igdtnum ).  Each
C                         element of this integer array contains an entry (in
C                         the order specified) of Grid Defintion Template 3.NN
C                         This element is actually a pointer to an array
C                         that holds the data.
C        gfld%igdtlen = Number of elements in gfld%igdtmpl().  i.e. number of
C                       entries in Grid Defintion Template 3.NN
C                       ( NN=gfld%igdtnum ).
C        gfld%list_opt() = (Used if gfld%numoct_opt .ne. 0)  This array
C                          contains the number of grid points contained in
C                          each row ( or column ).  (part of Section 3)
C                          This element is actually a pointer to an array
C                          that holds the data.  This pointer is nullified
C                          if gfld%numoct_opt=0.
C        gfld%num_opt = (Used if gfld%numoct_opt .ne. 0)  The number of entries
C                       in array ideflist.  i.e. number of rows ( or columns )
C                       for which optional grid points are defined.  This value
C                       is set to zero, if gfld%numoct_opt=0.
C        gfdl%ipdtnum = Product Definition Template Number (see Code Table 4.0)
C        gfld%ipdtmpl() = Contains the data values for the specified Product
C                         Definition Template ( N=gfdl%ipdtnum ).  Each element
C                         of this integer array contains an entry (in the
C                         order specified) of Product Defintion Template 4.N.
C                         This element is actually a pointer to an array
C                         that holds the data.
C        gfld%ipdtlen = Number of elements in gfld%ipdtmpl().  i.e. number of
C                       entries in Product Defintion Template 4.N
C                       ( N=gfdl%ipdtnum ).
C        gfld%coord_list() = Real array containing floating point values
C                            intended to document the vertical discretisation
C                            associated to model data on hybrid coordinate
C                            vertical levels.  (part of Section 4)
C                            This element is actually a pointer to an array
C                            that holds the data.
C        gfld%num_coord = number of values in array gfld%coord_list().
C        gfld%ndpts = Number of data points unpacked and returned.
C        gfld%idrtnum = Data Representation Template Number
C                       ( see Code Table 5.0)
C        gfld%idrtmpl() = Contains the data values for the specified Data
C                         Representation Template ( N=gfld%idrtnum ).  Each
C                         element of this integer array contains an entry
C                         (in the order specified) of Product Defintion
C                         Template 5.N.
C                         This element is actually a pointer to an array
C                         that holds the data.
C        gfld%idrtlen = Number of elements in gfld%idrtmpl().  i.e. number
C                       of entries in Data Representation Template 5.N
C                       ( N=gfld%idrtnum ).
C        gfld%unpacked = logical value indicating whether the bitmap and
C                        data values were unpacked.  If false,
C                        gfld%bmap and gfld%fld pointers are nullified.
C        gfld%expanded = Logical value indicating whether the data field
C                         was expanded to the grid in the case where a
C                         bit-map is present.  If true, the data points in
C                         gfld%fld match the grid points and zeros were
C                         inserted at grid points where data was bit-mapped
C                         out.  If false, the data values in gfld%fld were
C                         not expanded to the grid and are just a consecutive
C                         array of data points corresponding to each value of
C                         "1" in gfld%bmap.
C        gfld%ibmap = Bitmap indicator ( see Code Table 6.0 )
C                     0 = bitmap applies and is included in Section 6.
C                     1-253 = Predefined bitmap applies
C                     254 = Previously defined bitmap applies to this field
C                     255 = Bit map does not apply to this product.
C        gfld%bmap() = Logical*1 array containing decoded bitmap,
C                      if ibmap=0 or ibap=254.  Otherwise nullified.
C                      This element is actually a pointer to an array
C                      that holds the data.
C        gfld%fld() = Array of gfld%ndpts unpacked data points.
C                     This element is actually a pointer to an array
C                     that holds the data.
C     IRET         INTEGER RETURN CODE
C                    0      ALL OK
C                    97     ERROR READING GRIB FILE
C                    OTHER  GF_GETFLD GRIB UNPACKER RETURN CODE
C
C SUBPROGRAMS CALLED:
C   BAREAD         BYTE-ADDRESSABLE READ
C   GF_UNPACK6     UNAPCKS BIT_MAP SECTION
C   GF_UNPACK7     UNAPCKS DATA SECTION 
C
C REMARKS: 
C   DO NOT ENGAGE THE SAME LOGICAL UNIT FROM MORE THAN ONE PROCESSOR.
C   THIS SUBPROGRAM IS INTENDED FOR PRIVATE USE BY GETGB2 ROUTINES ONLY.
C
C   Note that derived type gribfield contains pointers to many
C   arrays of data.  The memory for these arrays is allocated
C   when the values in the arrays are set, to help minimize
C   problems with array overloading.  Because of this, users
C   are encouraged to free up this memory, when it is no longer
C   needed, by an explicit call to subroutine gf_free.
C   ( i.e.   CALL GF_FREE(GFLD) )
C
C ATTRIBUTES:
C   LANGUAGE: FORTRAN 90
C
C$$$
      USE GRIB_MOD

      INTEGER,INTENT(IN) :: LUGB
      CHARACTER(LEN=1),INTENT(IN) :: CINDEX(*)
      INTEGER,INTENT(OUT) :: IRET
      TYPE(GRIBFIELD) :: GFLD

      INTEGER :: LSKIP,SKIP6,SKIP7
      CHARACTER(LEN=1):: CSIZE(4)
      CHARACTER(LEN=1),ALLOCATABLE :: CTEMP(:)
      real,pointer,dimension(:) :: newfld

      interface
         subroutine gf_unpack6(cgrib,lcgrib,iofst,ngpts,ibmap,
     &                         bmap,ierr)
           character(len=1),intent(in) :: cgrib(lcgrib)
           integer,intent(in) :: lcgrib,ngpts
           integer,intent(inout) :: iofst
           integer,intent(out) :: ibmap
           integer,intent(out) :: ierr
           logical*1,pointer,dimension(:) :: bmap
         end subroutine gf_unpack6
         subroutine gf_unpack7(cgrib,lcgrib,iofst,igdsnum,igdstmpl,
     &                         idrsnum,idrstmpl,ndpts,fld,ierr)
           character(len=1),intent(in) :: cgrib(lcgrib)
           integer,intent(in) :: lcgrib,ndpts,idrsnum,igdsnum
           integer,intent(inout) :: iofst
           integer,pointer,dimension(:) :: idrstmpl,igdstmpl
           integer,intent(out) :: ierr
           real,pointer,dimension(:) :: fld
         end subroutine gf_unpack7
      end interface
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C  GET INFO
      NULLIFY(gfld%bmap,gfld%fld)
      IRET=0
      CALL G2LIB_GBYTE(CINDEX,LSKIP,4*8,4*8)
      CALL G2LIB_GBYTE(CINDEX,SKIP6,24*8,4*8)
      CALL G2LIB_GBYTE(CINDEX,SKIP7,28*8,4*8)

C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C  READ AND UNPACK BIT_MAP, IF PRESENT
      IF ( gfld%ibmap.eq.0.OR.gfld%ibmap.eq.254 ) THEN
         ISKIP=LSKIP+SKIP6
         CALL BAREAD(LUGB,ISKIP,4,LREAD,CSIZE)    ! GET LENGTH OF SECTION
         CALL G2LIB_GBYTE(CSIZE,ILEN,0,32)
         ALLOCATE(CTEMP(ILEN))
         CALL BAREAD(LUGB,ISKIP,ILEN,LREAD,CTEMP)  ! READ IN SECTION
         IF (ILEN.NE.LREAD) THEN
            IRET=97
            DEALLOCATE(CTEMP)
            RETURN
         ENDIF
         IOFST=0
         CALL GF_UNPACK6(CTEMP,ILEN,IOFST,gfld%ngrdpts,idum,
     &                   gfld%bmap,ierr)
         IF (IERR.NE.0) THEN
            IRET=98
            DEALLOCATE(CTEMP)
            RETURN
         ENDIF
         DEALLOCATE(CTEMP)
      ENDIF
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C  READ AND UNPACK DATA FIELD 
      ISKIP=LSKIP+SKIP7
      CALL BAREAD(LUGB,ISKIP,4,LREAD,CSIZE)    ! GET LENGTH OF SECTION
      CALL G2LIB_GBYTE(CSIZE,ILEN,0,32)
      ALLOCATE(CTEMP(ILEN))
      CALL BAREAD(LUGB,ISKIP,ILEN,LREAD,CTEMP)  ! READ IN SECTION
      IF (ILEN.NE.LREAD) THEN
         IRET=97
         DEALLOCATE(CTEMP)
         RETURN
      ENDIF
      IOFST=0
      CALL GF_UNPACK7(CTEMP,ILEN,IOFST,gfld%igdtnum,gfld%igdtmpl,
     &                   gfld%idrtnum,gfld%idrtmpl,gfld%ndpts,
     &                   gfld%fld,ierr)
      IF (IERR.NE.0) THEN
         IRET=98
         DEALLOCATE(CTEMP)
         RETURN
      ENDIF
      DEALLOCATE(CTEMP)
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      !  If bitmap is used with this field, expand data field
      !  to grid, if possible.
      if ( gfld%ibmap .ne. 255 .AND. associated(gfld%bmap) ) then
            allocate(newfld(gfld%ngrdpts))
            !newfld=0.0
            !newfld=unpack(lgfld%fld,lgfld%bmap,newfld)
            n=1
            do j=1,gfld%ngrdpts
                if ( gfld%bmap(j) ) then
                  newfld(j)=gfld%fld(n)
                  n=n+1
                else
                  newfld(j)=0.0
                endif
            enddo
            deallocate(gfld%fld);
            gfld%fld=>newfld;
            gfld%expanded=.true.
      else
         gfld%expanded=.true.
      endif
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      RETURN
      END