BTW, the MSDN documentation at

http://msdn.microsoft.com/en-us/library/e9b52ceh(v=vs.100).aspx

is a bit confusing.  Question 1:  when doing __control87_2(new, mask, &old, NULL), does the resulting value in old reflect the *new* FPU state or the old one?

Question 2:  in the example near the bottom of that page, there's code like:

    control_word_x87 = __control87_2(_PC_24, MCW_PC,
                                     &control_word_x87, 0);

This looks very odd: we're assigning to control_word_x87, *and* passing it as an output parameter to the call.  Moreover, from the documentation  the return value from __control87_2 is always 1 to indicate success, so I'm not sure why it's being assigned to control_word_x87.

Am I the only person who's confused by this?