From: Guillaume Melquiond (guillaume.melquiond_at_[hidden])
Date: 2003-12-12 12:04:55
Le ven 12/12/2003 à 17:08, Dan W. a écrit :
> > No need to go as far as using assembly language. There are C functions
> > that work just fine like nearbyint or rint (the second one is usually
> > faster). And if you are really looking for assembler, the frndint
> > instruction is available on x86 for exemple.
>
> Not familiar with those, but I just came up with something that should
> work...
[... snipped ...]
> -------------------------------------------------------------------
> (sorry if my syntax offends, I'm rusty in assembler these days)
>
> That should add up to just four integer instructions, with optims' ON.
> Not totally sure that the sign bit would always survive; would need to
> test it.
>
> Cheers!
Is this some kind of joke? What did you expect when you posted this
mail? Please refrain from going wild on a public-mailing list.
Most processors have an opcode to round a floating-point value to an
integer. For example, as I said, this instruction is called frndint on
x86 (how do you think floor, rint and ceil are coded?). Don't try to
emulate a floating-point unit by using a handful of integer operations.
First it will be completely wrong (it's not as easy as you seem to
believe), and second it will be slow.
Guillaume