I have bee trying to port Xtank. This involves porting a threads system which
uses setjmp/longjmp to provide context switching between threads. This 
seems to work fine most of the time but occasionally I get floating point 
exceptions running the binary with some configurations of the game.

Should setjmp save any floating point context for restoration by longjmp?
In the current implementation the only code to handle floating point 
registers in these routines is commented out. 

Mike