getgb.f

C> @file
C> @brief Find and unpack a grib message.
C> @author Mark Iredell @date 1994-04-01

C> Find and unpack a grib message.
C> Read a grib index file (or optionally the grib file itself)
C> to get the index buffer (i.e. table of contents) for the grib file.
C> (The index buffer is saved for use by future prospective calls.)
C> Find in the index buffer a reference to the grib message requested.
C> The grib message request specifies the number of messages to skip
C> and the unpacked pds and gds parameters.  (A requested parameter
C> of -1 means to allow any value of this parameter to be found.)
C> If the requested grib message is found, then it is read from the
C> grib file and unpacked. It's message number is returned along with
C> the unpacked pds and gds parameters, the unpacked bitmap (if any),
C> and the unpacked data. If the grib message is not found, then the
C> return code will be nonzero.
C>
C> @param[in] LUGB Integer unit of the unblocked grib data file
C> @param[in] LUGI Integer unit of the unblocked grib index file
C> (=0 to get index buffer from the grib file)
C> @param[in] JF Integer maximum number of data points to unpack
C> @param[in] J Integer number of messages to skip
C> (=0 to search from beginning)
C> (<0 to read index buffer and skip -1-j messages)
C> @param[in] JPDS Integer (200) pds parameters for which to search
C> (=-1 for wildcard)
C>  - 1 Id of center
C>  - 2 Generating process id number
C>  - 3 Grid definition
C>  - 4 Gds/bms flag (right adj copy of octet 8)
C>  - 5 Indicator of parameter
C>  - 6 Type of level
C>  - 7 Height/pressure , etc of level
C>  - 8 Year including (century-1)
C>  - 9 Month of year
C>  - 10 Day of month
C>  - 11 Hour of day
C>  - 12 Minute of hour
C>  - 13 Indicator of forecast time unit
C>  - 14 Time range 1
C>  - 15 Time range 2
C>  - 16 Time range flag
C>  - 17 Number included in average
C>  - 18 Version nr of grib specification
C>  - 19 Version nr of parameter table
C>  - 20 Nr missing from average/accumulation
C>  - 21 Century of reference time of data
C>  - 22 Units decimal scale factor
C>  - 23 Subcenter number
C>  - 24 Pds byte 29, for nmc ensemble products
C>   - 128 if forecast field error
C>   - 64 if bias corrected fcst field
C>   - 32 if smoothed field
C>   - warning: can be combination of more than 1
C>   - 25 pds byte 30, not used
C> @param[in] JGDS Integer (200) gds parameters for which to search
C> (only searched if jpds(3)=255) (=-1 for wildcard)
C> - 1 Data representation type
C> - 19 Number of vertical coordinate parameters
C> - 20 Octet number of the list of vertical coordinate
C> parameters or octet number of the list of numbers of points
C> in each row or 255 if neither are present
C> - 21 For grids with pl, number of points in grid
C> - 22 Number of words in each row
C> - Latitude/longitude grids
C>  - 2 n(i) nr points on latitude circle
C>  - 3 n(j) nr points on longitude meridian
C>  - 4 la(1) latitude of origin
C>  - 5 lo(1) longitude of origin
C>  - 6 resolution flag (right adj copy of octet 17)
C>  - 7 la(2) latitude of extreme point
C>  - 8 lo(2) longitude of extreme point
C>  - 9 di longitudinal direction of increment
C>  - 10 dj latitudinal direction increment
C>  - 11 scanning mode flag (right adj copy of octet 28)
C> - Gaussian  grids
C>  - 2 n(i) nr points on latitude circle
C>  - 3 n(j) nr points on longitude meridian
C>  - 4 la(1) latitude of origin
C>  - 5 lo(1) longitude of origin
C>  - 6 resolution flag  (right adj copy of octet 17)
C>  - 7 la(2) latitude of extreme point
C>  - 8 lo(2) longitude of extreme point
C>  - 9 di longitudinal direction of increment
C>  - 10 n nr of circles pole to equator
C>  - 11 scanning mode flag (right adj copy of octet 28)
C>  - 12 nv nr of vert coord parameters
C>  - 13 pv octet nr of list of vert coord parameters or
C>   - pl location of the list of numbers of points in
C> each row (if no vert coord parameters are present) or
C> 255 if neither are present
C> - Polar stereographic grids
C>  - 2 n(i) nr points along lat circle
C>  - 3 n(j) nr points along lon circle
C>  - 4 la(1) latitude of origin
C>  - 5 lo(1) longitude of origin
C>  - 6 Resolution flag  (right adj copy of octet 17)
C>  - 7 lov grid orientation
C>  - 8 dx - x direction increment
C>  - 9 dy - y direction increment
C>  - 10 Projection center flag
C>  - 11 Scanning mode (right adj copy of octet 28)
C> - Spherical harmonic coefficients
C>  - 2 j pentagonal resolution parameter
C>  - 3 k pentagonal resolution parameter
C>  - 4 m pentagonal resolution parameter
C>  - 5 Representation type
C>  - 6 Coefficient storage mode
C> - Mercator grids
C>  - 2 n(i) nr points on latitude circle
C>  - 3 n(j) nr points on longitude meridian
C>  - 4 la(1) latitude of origin
C>  - 5 lo(1) longitude of origin
C>  - 6 Resolution flag (right adj copy of octet 17)
C>  - 7 la(2) latitude of last grid point
C>  - 8 lo(2) longitude of last grid point
C>  - 9 latit - latitude of projection intersection
C>  - 10 Reserved
C>  - 11 Scanning mode flag (right adj copy of octet 28)
C>  - 12 Longitudinal dir grid length
C>  - 13 Latitudinal dir grid length
C> - lambert conformal grids
C>  - 2 nx nr points along x-axis
C>  - 3 ny nr points along y-axis
C>  - 4 la1 lat of origin (lower left)
C>  - 5 lo1 lon of origin (lower left)
C>  - 6 Resolution (right adj copy of octet 17)
C>  - 7 lov - orientation of grid
C>  - 8 dx - x-dir increment
C>  - 9 dy - y-dir increment
C>  - 10 Projection center flag
C>  - 11 Scanning mode flag (right adj copy of octet 28)
C>  - 12 latin 1 - first lat from pole of secant cone inter
C>  - 13 latin 2 - second lat from pole of secant cone inter
C> @param[out] KF Integer number of data points unpacked
C> @param[out] K Integer message number unpacked
C> (can be same as j in calling program
C> in order to facilitate multiple searches)
C> @param[out] KPDS Integer (200) unpacked pds parameters
C> @param[out] KGDS Integer (200) unpacked gds parameters
C> @param[out] LB Logical*1 (kf) unpacked bitmap if present
C> @param[out] F Real (kf) unpacked data
C> @param[out] IRET Integer return code
C>  - 0 All ok
C>  - 96 Error reading index file
C>  - 97 Error reading grib file
C>  - 98 Number of data points greater than jf
C>  - 99 Request not found
C>  - other w3fi63 grib unpacker return code
C>
C> @note In order to unpack grib from a multiprocessing environment
C> where each processor is attempting to read from its own pair of
C> logical units, one must directly call subprogram getgbm as below,
C> allocating a private copy of cbuf, nlen and nnum to each processor.
C> do not engage the same logical unit from more than one processor.
C> @author Mark Iredell @date 1994-04-01
C-----------------------------------------------------------------------
      SUBROUTINE GETGB(LUGB,LUGI,JF,J,JPDS,JGDS,
     &                 KF,K,KPDS,KGDS,LB,F,IRET)
      INTEGER JPDS(200),JGDS(200),KPDS(200),KGDS(200)
      LOGICAL*1 LB(JF)
      REAL F(JF)
      PARAMETER(MBUF=256*1024)
      CHARACTER CBUF(MBUF)
      SAVE CBUF,NLEN,NNUM,MNUM
      DATA LUX/0/
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C  DETERMINE WHETHER INDEX BUFFER NEEDS TO BE INITIALIZED
      IF(LUGI.GT.0.AND.(J.LT.0.OR.LUGI.NE.LUX)) THEN
        LUX=LUGI
        JJ=MIN(J,-1-J)
      ELSEIF(LUGI.LE.0.AND.(J.LT.0.OR.LUGB.NE.LUX)) THEN
        LUX=LUGB
        JJ=MIN(J,-1-J)
      ELSE
        JJ=J
      ENDIF
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
C  FIND AND UNPACK GRIB MESSAGE
      CALL GETGBM(LUGB,LUGI,JF,JJ,JPDS,JGDS,
     &            MBUF,CBUF,NLEN,NNUM,MNUM,
     &            KF,K,KPDS,KGDS,LB,F,IRET)
      IF(IRET.EQ.96) LUX=0
C - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
      RETURN
      END