vfp_estimate_sqrt_significand
u32 vfp_estimate_sqrt_significand(u32 exponent, u32 significand);
vdd.significand = (u64)vfp_estimate_sqrt_significand(vdm.exponent, vdm.significand >> 32) << 31;
vsd.significand = vfp_estimate_sqrt_significand(vsm.exponent, vsm.significand) + 2;