_C_STD_BEGIN
#if !defined(MRTDLL)
_C_LIB_DECL
#endif /* defined(MRTDLL) */
_CRTIMP2_PURE short __CLRCALL_PURE_OR_CDECL _FDunscale(short *pex, float *px)
{ /* separate *px to 1/2 <= |frac| < 1 and 2^*pex */
_Fval *ps = (_Fval *)(char *)px;
short xchar = (ps->_Sh[_F0] & _FMASK) >> _FOFF;
if (xchar == _FMAX)
{ /* NaN or INF */
*pex = 0;
return ((ps->_Sh[_F0] & _FFRAC) != 0 || ps->_Sh[_F1] != 0
? _NANCODE : _INFCODE);
}
else if (0 < xchar || (xchar = _FDnorm(ps)) <= 0)
{ /* finite, reduce to [1/2, 1) */
ps->_Sh[_F0] = (ps->_Sh[_F0] & ~_FMASK) | _FBIAS << _FOFF;
*pex = xchar - _FBIAS;
return (_FINITE);
}
else
{ /* zero */
*pex = 0;
return (0);
}
}
_STD_BEGIN
_CRTIMP2 short _FDscale(float *px, long lexp)
{ /* scale *px by 2^xexp with checking */
unsigned short *ps = (unsigned short *)px;
short xchar = (ps[_F0] & _FMASK) >> _FOFF;
if (xchar == _FMAX)
return ((ps[_F0] & _FFRAC) != 0 || ps[_F1] != 0
? NAN : INF);
else if (xchar == 0 && 0 < (xchar = _FDnorm(ps)))
return (0);
lexp += xchar;
if (_FMAX <= lexp)
{ /* overflow, return +/-INF */
*px = ps[_F0] & _FSIGN ? -_FInf._F : _FInf._F;
return (INF);
}
else if (0 < lexp)
{ /* finite result, repack */
ps[_F0] = ps[_F0] & ~_FMASK | (short)lexp << _FOFF;
return (FINITE);
}
else
{ /* denormalized, scale */
unsigned short sign = ps[_F0] & _FSIGN;
ps[_F0] = 1 << _FOFF | ps[_F0] & _FFRAC;
if (--lexp < -(16+_FOFF))
{ /* underflow, return +/-0 */
ps[_F0] = sign, ps[_F1] = 0;
return (0);
}
else
{ /* nonzero, align fraction */
short xexp = (short)lexp;
if (xexp <= -16)
ps[_F1] = ps[_F0], ps[_F0] = 0, xexp += 16;
if ((xexp = -xexp) != 0)
{ /* scale by bits */
ps[_F1] = ps[_F1] >> xexp
| ps[_F0] << (16 - xexp);
ps[_F0] >>= xexp;
}
ps[_F0] |= sign;
return (FINITE);
}
}
