TRACE_ALU3 (MY_INDEX, result, Source1, Source2);
*rDest = result;
// NOTE - the book has 15.1 which conflicts with subu.
-31.Dest,26.Source2,21.0b101101,15.1,14.UnsignedImmediate::::subu i
+31.Dest,26.Source2,21.0b101101,15.1,14.SignedImmediate::::subu i
do_subu (_SD, rDest, vSource1, vSource2);
31.Dest,26.Source2,21.0b11101101,13.1,12.0,11./,4.Source1::::subu r
do_subu (_SD, rDest, vSource1, vSource2);