VAX_SNG_BIAS
is.exp = vs.exp - VAX_SNG_BIAS + IEEE_SNG_BIAS;
vsp->exp = is.exp - IEEE_SNG_BIAS + VAX_SNG_BIAS;
is.exp = vs.exp - VAX_SNG_BIAS + IEEE_SNG_BIAS;
vsp->exp = is.exp - IEEE_SNG_BIAS + VAX_SNG_BIAS;