/* _Dunscale function -- IEEE 754 version */
#include "xmath.h"

short _Dunscale(short *pex, double *px)
        {       /* separate *px to 1/2 <= |frac| < 1 and 2^*pex */
        unsigned short *ps = (unsigned short *)px;
        short xchar = (ps[_D0] & _DMASK) >> _DOFF;

        if (xchar == _DMAX)
                {       /* NaN or INF */
                *pex = 0;
                return (ps[_D0] & _DFRAC || ps[_D1]
                        || ps[_D2] || ps[_D3] ? NAN : INF);
                }
        else if (0 < xchar || (xchar = _Dnorm(ps)) != 0)
                {       /* finite, reduce to [1/2, 1) */
                ps[_D0] = ps[_D0] & ~_DMASK | _DBIAS << _DOFF;
                *pex = xchar - _DBIAS;
                return (FINITE);
                }
        else
                {       /* zero */
                *pex = 0;
                return (0);
                }
        }
