Re: [PATCH 2/5] Convert resource to u64 from unsigned long

[Andreas Dilger]

On Jan 13, 2005  16:28 -0700, Dave wrote:
> Fixed some of the drivers as example just to get working on i386.
> +     /*
> +      * FIXME: apparently ia32 does not have u64 divide implementation
> +      * we cast the pci_resource_len to u32 for the time being
> +      * this probably should be fixed to support u64 for ia32
> +      * and other archs that do not have u64 divide
> +      */
> +#if BIS_PER_LONG == 64
>       maxnr = (pci_resource_len(dev, bar) - board->first_offset) /
>               (8 << board->reg_shift);
> +#else
> +     maxnr = ((u32)pci_resource_len(dev, bar) - board->first_offset) /
> +             (8 << board->reg_shift);
> +#endif
                                                                                
One of the reasons that ia32 doesn't support 64-bit divide directly is
because it is a big red flag that you are probably doing something wrong.
This is a prime example - why do a divide when you could do a shift:
                                                                                
        maxnr = (pci_resource_len(dev, bar) - board->first_offset) >>
                (board->reg_shift + 3);

Cheers, Andreas
--
Andreas Dilger
http://sourceforge.net/projects/ext2resize/
http://members.shaw.ca/adilger/             http://members.shaw.ca/golinux/

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