Re: [Linux-ia64] avoiding float underflow software assist

Jes Sorensen
2000-10-12T16:13:15Z

>>>>> "Pete" = Pete Wyckoff <pw@osc.edu> writes:

Pete> jes@linuxcare.com said:
>> We discussed this recently and David strongly opted for glibc
>> setting s2/s3 the same way we set s0. I need to look closer at this
>> in order to figure out how to deal with the get-then-set case but I
>> think it's coming.

Pete> There's this method of masking just the control bits of sf0 into
Pete> sf* if you'd rather not provide direct library access to the
Pete> fpsr. E.g., to set ftz in s0:

Pete> asm volatile("fsetc.s0 0x7f, 0x01");

Pete> Or dup s0 into s2:

Pete> asm volatile("fsetc.s2 0x7f, 0x00");

Pete> Not sure if/why intel gave us this instruction. Perhaps
Pete> switching speed is important to some apps.

Hmmm need to go read manuals when I get back from Atlanta.

Thanks
Jes