On Tue, Sep 19, 2000 at 02:58:01AM -0700, Jeremy Higdon wrote:
> Hello,
>
> I'm using a 64 bit variable in a switch statement. Gcc is generating code
> which make calls to __ucmpdi2, a function defined in libgcc. I figured
> out that it was the switch statement from examining the generated code.
>
> The question is whether I should change C code to avoid constructions
> which make calls to this routine (a little hard to determine a priori)
> or if there is an appropriate way to add this to the kernel.
Yes do change it.
Is the value-space for the case's a LONG LONG, or
mere set of INTs or LONGs ?
Can you simply (and reliably) cast the variable
into e.g. 'long' ? Or should you use if / else if / ..
chains ?
> Best I can tell, __ucmpdi2 takes two 64 bit unsigned args, returning
> 0 if the 1st arg is less than the 2nd, 2 if greater, 1 if equal. For
> now, I have defined the function in my driver with those semantics.
> For obvious reasons, I don't consider this a viable long term option.
>
> thanks
> jeremy
/Matti Aarnio
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