Back to index

glibc  2.9
Functions
s_ilogbl.c File Reference
#include <limits.h>
#include "math.h"
#include "math_private.h"

Go to the source code of this file.

Functions

int __ilogbl (long double x)

Function Documentation

int __ilogbl ( long double  x)

Definition at line 35 of file s_ilogbl.c.

{
       int32_t es,hx,lx,ix;

       GET_LDOUBLE_EXP(es,x);
       es &= 0x7fff;
       if(es==0) {
           GET_LDOUBLE_WORDS(es,hx,lx,x);
           if((hx|lx)==0)
              return FP_ILOGB0;    /* ilogbl(0) = FP_ILOGB0 */
           else                    /* subnormal x */
              if(hx==0) {
                  for (ix = -16415; lx>0; lx<<=1) ix -=1;
              } else {
                  for (ix = -16383; hx>0; hx<<=1) ix -=1;
              }
           return ix;
       }
       else if (es<0x7fff) return es-0x3fff;
       else if (FP_ILOGBNAN != INT_MAX)
       {
           GET_LDOUBLE_WORDS(es,hx,lx,x);
           if (((hx & 0x7fffffff)|lx) == 0)
             /* ISO C99 requires ilogbl(+-Inf) == INT_MAX.  */
             return INT_MAX;
       }
       return FP_ILOGBNAN;
}