s in assembly language.
<li> Fujitsu VPP: Write <code>mpn_mul_basecase</code> and
     <code>mpn_sqr_basecase</code>.  This should use a "vertical multiplication
     method", to avoid carry propagation.  splitting one of the operands in
     11-bit chunks.
<li> Pentium: <code>mpn_lshift</code> by 31 should use the special rshift
     by 1 code, and vice versa <code>mpn_rshift</code> by 31 should use the
     special lshift by 1.  This would be best as a jump across to the other
     routine, could let both