Implement GFS weatherdata plugin

refs #556

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

@@ -0,0 +1,78 @@
+#include "grib2.h"
+
+void rdieee(g2int *rieee,g2float *a,g2int num)
+//$$$  SUBPROGRAM DOCUMENTATION BLOCK
+//                .      .    .                                       .
+// SUBPROGRAM:    rdieee 
+//   PRGMMR: Gilbert         ORG: W/NP11    DATE: 2002-10-25
+//
+// ABSTRACT: This subroutine reads a list of real values in 
+//   32-bit IEEE floating point format.
+//
+// PROGRAM HISTORY LOG:
+// 2002-10-25  Gilbert
+//
+// USAGE:    void rdieee(g2int *rieee,g2float *a,g2int num)
+//   INPUT ARGUMENT LIST:
+//     rieee    - g2int array of floating point values in 32-bit IEEE format.
+//     num      - Number of floating point values to convert.
+//
+//   OUTPUT ARGUMENT LIST:      
+//     a        - float array of real values.  a must be allocated with at
+//                least 4*num bytes of memory before calling this function.
+//
+// REMARKS: None
+//
+// ATTRIBUTES:
+//   LANGUAGE: C
+//   MACHINE:  IBM SP
+//
+//$$$
+{
+
+      g2int  j;
+      g2int  isign,iexp,imant;
+
+      g2float  sign,temp;
+      static g2float  two23,two126;
+      static g2int test=0;
+      g2intu msk1=0x80000000;        // 10000000000000000000000000000000 binary
+      g2int msk2=0x7F800000;         // 01111111100000000000000000000000 binary
+      g2int msk3=0x007FFFFF;         // 00000000011111111111111111111111 binary
+
+      if ( test == 0 ) {
+         two23=(g2float)int_power(2.0,-23);
+         two126=(g2float)int_power(2.0,-126);
+         test=1;
+      }
+
+      for (j=0;j<num;j++) {
+//
+//  Extract sign bit, exponent, and mantissa
+//
+        isign=(rieee[j]&msk1)>>31;
+        iexp=(rieee[j]&msk2)>>23;
+        imant=(rieee[j]&msk3);
+        //printf("SAGieee= %ld %ld %ld\n",isign,iexp,imant);
+
+        sign=1.0;
+        if (isign == 1) sign=-1.0;
+        
+        if ( (iexp > 0) && (iexp < 255) ) {
+          temp=(g2float)int_power(2.0,(iexp-127));
+          a[j]=sign*temp*(1.0+(two23*(g2float)imant));
+        }
+        else if ( iexp == 0 ) {
+          if ( imant != 0 )
+            a[j]=sign*two126*two23*(g2float)imant;
+          else
+            a[j]=sign*0.0;
+          
+        }
+        else if ( iexp == 255 )
+           a[j]=sign*(1E+37);
+
+
+      }
+
+}