rdieee.c

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#include "grib2.h"
 
void rdieee(g2int *rieee,g2float *a,g2int num)
{
 
    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);
 
 
    }
 
}