#include <limits.h>
#include "libm.h"

int ilogb(double x)
{
        #pragma STDC FENV_ACCESS ON
        union {double f; uint64_t i;} u = {x};
        uint64_t i = u.i;
        int e = i>>52 & 0x7ff;

        if (!e) {
                i <<= 12;
                if (i == 0) {
                        FORCE_EVAL(0/0.0f);
                        return FP_ILOGB0;
                }
                /* subnormal x */
                for (e = -0x3ff; i>>63 == 0; e--, i<<=1);
                return e;
        }
        if (e == 0x7ff) {
                FORCE_EVAL(0/0.0f);
                return i<<12 ? FP_ILOGBNAN : INT_MAX;
        }
        return e - 0x3ff;
}