SUBROUTINE GDSWZD_C(KGDS,IOPT,NPTS,FILL,XPTS,YPTS,RLON,RLAT,NRET, &
                     CROT,SROT,XLON,XLAT,YLON,YLAT,AREA) BIND(C, NAME='gdswzd')
!$$$  SUBPROGRAM DOCUMENTATION BLOCK
!
! SUBPROGRAM:  GDSWZD_C     'C' WRAPPER FOR ROUTINE GDSWZD
!   PRGMMR: JOVIC         ORG: W/NMC23       DATE: 2016-04-10
!
! ABSTRACT:  USE THIS ROUTINE TO CALL 'GDSWZD' FROM A 'C' OR 'C++' PROGRAM.
!            TAKES ADVANTAGE OF THE FORTRAN/C INTEROPERABILITY STANDARD.
!
! PROGRAM HISTORY LOG:
! 2016-04-10  JOVIC  
!
! USAGE:    
!
!  EXAMPLE: MIXED PRECSION IPLIB CALL
!
!  include "iplib.h"
!
!  int kgds[200];
!  int iopt, npts, nret;
!  double fill;
!  double *xpts, *ypts, *rlon, *rlat;
!  double *crot, *srot, *xlon, *xlat, *ylon, *ylat, *area;
!
!  gdswzd(kgds, iopt, npts, fill,
!         xpts, ypts, rlon, rlat,
!         &nret, crot, srot, xlon,
!         xlat, ylon, ylat, area);
!
!  INPUT ARGUMENT LIST:
!     KGDS     - INTEGER (200) GDS PARAMETERS AS DECODED BY W3FI63
!     IOPT     - INTEGER OPTION FLAG
!                ( 0 TO COMPUTE EARTH COORDS OF ALL THE GRID POINTS)
!                (+1 TO COMPUTE EARTH COORDS OF SELECTED GRID COORDS)
!                (-1 TO COMPUTE GRID COORDS OF SELECTED EARTH COORDS)
!     NPTS     - INTEGER MAXIMUM NUMBER OF COORDINATES
!     FILL     - REAL FILL VALUE TO SET INVALID OUTPUT DATA
!                (MUST BE IMPOSSIBLE VALUE; SUGGESTED VALUE: -9999.)
!     XPTS     - REAL (NPTS) GRID X POINT COORDINATES IF IOPT>0
!     YPTS     - REAL (NPTS) GRID Y POINT COORDINATES IF IOPT>0
!     RLON     - REAL (NPTS) EARTH LONGITUDES IN DEGREES E IF IOPT<0
!                (ACCEPTABLE RANGE: -360. TO 360.)
!     RLAT     - REAL (NPTS) EARTH LATITUDES IN DEGREES N IF IOPT<0
!                (ACCEPTABLE RANGE: -90. TO 90.)
!
!  OUTPUT ARGUMENT LIST:
!     XPTS     - REAL (NPTS) GRID X POINT COORDINATES IF IOPT<=0
!     YPTS     - REAL (NPTS) GRID Y POINT COORDINATES IF IOPT<=0
!     RLON     - REAL (NPTS) EARTH LONGITUDES IN DEGREES E IF IOPT>=0
!     RLAT     - REAL (NPTS) EARTH LATITUDES IN DEGREES N IF IOPT>=0
!     NRET     - INTEGER NUMBER OF VALID POINTS COMPUTED
!                (-1 IF PROJECTION UNRECOGNIZED)
!     CROT     - REAL (NPTS) CLOCKWISE VECTOR ROTATION COSINES
!     SROT     - REAL (NPTS) CLOCKWISE VECTOR ROTATION SINES
!                (UGRID=CROT*UEARTH-SROT*VEARTH;
!                 VGRID=SROT*UEARTH+CROT*VEARTH)
!     XLON     - REAL (NPTS) DX/DLON IN 1/DEGREES
!     XLAT     - REAL (NPTS) DX/DLAT IN 1/DEGREES
!     YLON     - REAL (NPTS) DY/DLON IN 1/DEGREES
!     YLAT     - REAL (NPTS) DY/DLAT IN 1/DEGREES
!     AREA     - REAL (NPTS) AREA WEIGHTS IN M**2
!                (PROPORTIONAL TO THE SQUARE OF THE MAP FACTOR
!                 IN THE CASE OF CONFORMAL PROJECTIONS)
!
! SUBPROGRAMS CALLED:
!   GDSWZD     GDS WIZARD
!
! ATTRIBUTES:
!   LANGUAGE: FORTRAN 90
!
!$$$
!
 USE, INTRINSIC :: ISO_C_BINDING

 USE GDSWZD_MOD

 IMPLICIT NONE
 
#if (LSIZE==8)
 INTEGER(KIND=C_LONG), INTENT(IN)         :: KGDS(200)
 INTEGER(KIND=C_LONG), VALUE, INTENT(IN)  :: IOPT
 INTEGER(KIND=C_LONG), VALUE, INTENT(IN)  :: NPTS
 INTEGER(KIND=C_LONG), INTENT(OUT)        :: NRET
#else
 INTEGER(KIND=C_INT),  INTENT(IN)         :: KGDS(200)
 INTEGER(KIND=C_INT),  VALUE, INTENT(IN)  :: IOPT
 INTEGER(KIND=C_INT),  VALUE, INTENT(IN)  :: NPTS
 INTEGER(KIND=C_INT),  INTENT(OUT)        :: NRET
#endif

#if (LSIZE==8 || LSIZE==D)
 REAL(KIND=C_DOUBLE), VALUE, INTENT(IN)   :: FILL
 REAL(KIND=C_DOUBLE), INTENT(INOUT)       :: XPTS(NPTS),YPTS(NPTS),RLON(NPTS),RLAT(NPTS)
 REAL(KIND=C_DOUBLE), INTENT(OUT)         :: CROT(NPTS),SROT(NPTS),XLON(NPTS),XLAT(NPTS)
 REAL(KIND=C_DOUBLE), INTENT(OUT)         :: YLON(NPTS),YLAT(NPTS),AREA(NPTS)
#else
 REAL(KIND=C_FLOAT), VALUE, INTENT(IN)    :: FILL
 REAL(KIND=C_FLOAT), INTENT(INOUT)        :: XPTS(NPTS),YPTS(NPTS),RLON(NPTS),RLAT(NPTS)
 REAL(KIND=C_FLOAT), INTENT(OUT)          :: CROT(NPTS),SROT(NPTS),XLON(NPTS),XLAT(NPTS)
 REAL(KIND=C_FLOAT), INTENT(OUT)          :: YLON(NPTS),YLAT(NPTS),AREA(NPTS)
#endif

 CALL GDSWZD(KGDS,IOPT,NPTS,FILL,XPTS,YPTS,RLON,RLAT,NRET, &
             CROT,SROT,XLON,XLAT,YLON,YLAT,AREA)

 END SUBROUTINE GDSWZD_C