Implement GFS weatherdata plugin

refs #556

src/plugins/weatherdata/gfs/g2clib/simunpack.c

@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include "grib2.h"
+
+
+g2int simunpack(unsigned char *cpack,g2int *idrstmpl,g2int ndpts,g2float *fld)
+////$$$  SUBPROGRAM DOCUMENTATION BLOCK
+//                .      .    .                                       .
+// SUBPROGRAM:    simunpack
+//   PRGMMR: Gilbert          ORG: W/NP11    DATE: 2002-10-29
+//
+// ABSTRACT: This subroutine unpacks a data field that was packed using a 
+//   simple packing algorithm as defined in the GRIB2 documention,
+//   using info from the GRIB2 Data Representation Template 5.0.
+//
+// PROGRAM HISTORY LOG:
+// 2002-10-29  Gilbert
+//
+// USAGE:    int simunpack(unsigned char *cpack,g2int *idrstmpl,g2int ndpts,
+//                         g2float *fld)
+//   INPUT ARGUMENT LIST:
+//     cpack    - pointer to the packed data field.
+//     idrstmpl - pointer to the array of values for Data Representation
+//                Template 5.0
+//     ndpts    - The number of data values to unpack
+//
+//   OUTPUT ARGUMENT LIST:
+//     fld      - Contains the unpacked data values.  fld must be allocated
+//                with at least ndpts*sizeof(g2float) bytes before
+//                calling this routine.
+//
+// REMARKS: None
+//
+// ATTRIBUTES:
+//   LANGUAGE: C
+//   MACHINE:  
+//
+//$$$//
+{
+
+      g2int  *ifld;
+      g2int  j,nbits,itype;
+      g2float ref,bscale,dscale;
+
+      
+      rdieee(idrstmpl+0,&ref,1);
+      bscale = int_power(2.0,idrstmpl[1]);
+      dscale = int_power(10.0,-idrstmpl[2]);
+      nbits = idrstmpl[3];
+      itype = idrstmpl[4];
+
+      ifld=(g2int *)calloc(ndpts,sizeof(g2int));
+      if ( ifld == 0 ) {
+         fprintf(stderr,"Could not allocate space in simunpack.\n  Data field NOT upacked.\n");
+         return(1);
+      }
+      
+//
+//  if nbits equals 0, we have a constant field where the reference value
+//  is the data value at each gridpoint
+//
+      if (nbits != 0) {
+         gbits(cpack,ifld,0,nbits,0,ndpts);
+         for (j=0;j<ndpts;j++) {
+           fld[j]=(((g2float)ifld[j]*bscale)+ref)*dscale;
+         }
+      }
+      else {
+         for (j=0;j<ndpts;j++) {
+           fld[j]=ref;
+         }
+      }
+
+      free(ifld);
+      return(0);
+}